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Efavirenz, lamivudine, and tenofovir disoproxil fumarate: Drug information

Efavirenz, lamivudine, and tenofovir disoproxil fumarate: Drug information
(For additional information see "Efavirenz, lamivudine, and tenofovir disoproxil fumarate: Patient drug information" and see "Efavirenz, lamivudine, and tenofovir disoproxil fumarate: Pediatric drug information")

For abbreviations, symbols, and age group definitions used in Lexicomp (show table)
ALERT: US Boxed Warning
Post treatment acute exacerbation of hepatitis B

Severe acute exacerbations of hepatitis B have been reported in patients who are co-infected with hepatitis B virus (HBV) and human immunodeficiency virus (HIV-1) and have discontinued lamivudine or tenofovir disoproxil fumarate. Monitor hepatic function closely in these patients and, if appropriate, initiate anti-hepatitis B treatment.

Brand Names: US
  • Symfi;
  • Symfi Lo
Pharmacologic Category
  • Antiretroviral, Reverse Transcriptase Inhibitor, Non-nucleoside (Anti-HIV);
  • Antiretroviral, Reverse Transcriptase Inhibitor, Nucleoside (Anti-HIV);
  • Antiretroviral, Reverse Transcriptase Inhibitor, Nucleotide (Anti-HIV)
Dosing: Adult
HIV-1 infection, treatment

HIV-1 infection, treatment:

Symfi: Oral: One tablet (efavirenz 600 mg/lamivudine 300 mg/tenofovir disoproxil fumarate 300 mg) once daily.

Symfi Lo: Oral: One tablet (efavirenz 400 mg/lamivudine 300 mg/tenofovir disoproxil fumarate 300 mg) once daily.

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Kidney Impairment: Adult

Chronic kidney disease prior to treatment:

CrCl ≥50 mL/minute: No dosage adjustment necessary.

CrCl <50 mL/minute: Use is not recommended.

End-stage renal disease (ESRD) requiring hemodialysis: Use is not recommended.

Acute kidney injury during treatment:

The Infectious Diseases Society of America guidelines recommend discontinuing tenofovir disoproxil fumarate (and substituting with alternative antiretroviral therapy) in HIV-infected patients who develop a decline in GFR (a >25% decrease in GFR from baseline and to a level of <60 mL/minute/1.73 m2) during use, particularly in the presence of proximal tubular dysfunction (eg, euglycemic glycosuria, increased urinary phosphorus excretion and hypophosphatemia, proteinuria [new onset or worsening]) (Ref).

Dosing: Hepatic Impairment: Adult

Hepatic impairment prior to treatment:

Mild hepatic impairment (Child-Pugh class A): No dosage adjustment necessary; use with caution.

Moderate or severe hepatic impairment (Child-Pugh classes B and C): Use is not recommended.

Hepatotoxicity during treatment:

Discontinue treatment if elevation of serum transaminases is accompanied by signs or symptoms of hepatitis or hepatic decompensation; consider discontinuing treatment in patients with persistent elevations of serum transaminases >5 times ULN.

Dosing: Adjustment for Toxicity: Adult

Rash: Treatment may be reinitiated in patients interrupting therapy for mild to moderate rashes; discontinue use and consider alternative therapy if severe rash associated with blistering, desquamation, mucosal involvement, or fever develops.

Dosing: Older Adult

Refer to adult dosing.

Dosing: Pediatric

(For additional information see "Efavirenz, lamivudine, and tenofovir disoproxil fumarate: Pediatric drug information")

Note: International Considerations: Doses are expressed as tenofovir disoproxil fumarate salt, consistent with US labeling; in some other countries, dosing may be expressed as tenofovir disoproxil base. Tenofovir disoproxil fumarate 300 mg is equivalent to tenofovir disoproxil base 245 mg.

HIV-1 infection

HIV-1 infection: Note: Gene mutation and ARV resistance patterns should be evaluated (refer to https://www.iasusa.org/ for more information) when necessary.

Symfi Lo (efavirenz 400 mg/lamivudine 300 mg/tenofovir disoproxil fumarate 300 mg per tablet): Pediatric patients weighing ≥35 kg: Oral: One tablet once daily.

Symfi (efavirenz 600 mg/lamivudine 300 mg/tenofovir disoproxil fumarate 300 mg per tablet): Pediatric patients weighing ≥40 kg: Oral: One tablet once daily.

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Kidney Impairment: Pediatric

CrCl ≥50 mL/minute: No dosage adjustment needed.

CrCl <50 mL/minute: Use not recommended.

End-stage renal disease (ESRD) requiring hemodialysis: Use is not recommended.

Dosing: Hepatic Impairment: Pediatric

Mild hepatic impairment: Use with caution.

Moderate to severe hepatic impairment: Not recommended.

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Also see individual agents.

>10%:

Cardiovascular: Increased serum creatine kinase (grades 3/4: 12%)

Dermatologic: Skin rash (18%)

Endocrine & metabolic: Increased serum cholesterol (grades 3/4: 19%)

Gastrointestinal: Diarrhea (11%)

Nervous system: Headache (14%), pain (13%), depression (11%)

Neuromuscular & skeletal: Decreased bone mineral density (28%)

1% to 10%:

Endocrine & metabolic: Increased amylase (grades 3/4: 9%), increased serum triglycerides (grades 3/4: 1%), lipodystrophy (1%)

Gastrointestinal: Nausea (8%), abdominal pain (7%), vomiting (5%), dyspepsia (4%)

Genitourinary: Hematuria (grades 3/4: 7%)

Hematologic & oncologic: Decreased neutrophils (grades 3/4: 3%)

Hepatic: Increased serum aspartate aminotransferase (grades 3/4: 5%), increased serum alanine aminotransferase (grades 3/4: 4%)

Nervous system: Anxiety (6%), insomnia (5%), dizziness (3%), peripheral neuropathy (1%)

Neuromuscular & skeletal: Back pain (9%), asthenia (6%), arthralgia (5%), myalgia (3%)

Respiratory: Pneumonia (5%)

Miscellaneous: Fever (8%)

Frequency not defined: Hepatic: Exacerbation of hepatitis B

Contraindications

Hypersensitivity (eg, Stevens-Johnson syndrome, erythema multiforme, or toxic skin eruptions) to efavirenz, lamivudine, tenofovir disoproxil fumarate or any component of the formulation; coadministration with elbasvir and grazoprevir.

Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Warnings/Precautions

Concerns related to adverse effects:

• CNS effects: CNS symptoms (eg, insomnia, abnormal dreams, hallucinations) have been reported with efavirenz; symptoms usually start during first 1 to 2 days of treatment and generally resolve after 2 to 4 weeks; administration at bedtime may improve tolerability of CNS symptoms. May also cause CNS depression (eg, impaired concentration, dizziness or drowsiness); avoid potentially hazardous tasks, such as driving or operating machinery. Late-onset neurotoxicity, including ataxia and encephalopathy, may occur months to years after initiation of efavirenz therapy. Some of these events have been reported in patients with CYP2B6 genetic polymorphisms (associated with increased efavirenz levels at standard doses).

• Decreased bone mineral density: In clinical trials, tenofovir disoproxil fumarate has been associated with decreases in bone mineral density in HIV-1 infected adults and increases in bone metabolism markers. Serum parathyroid hormone and 1,25 vitamin D levels were also higher. Effects on long-term bone health and future fracture risk in adult and pediatric patients, including long-term effects on skeletal growth in pediatric patients and effects of extended duration in younger children, are unknown. Consider calcium and vitamin D supplementation for all patients; effect of supplementation has not been studied but may be beneficial. Long-term bone health and fracture risk unknown. If abnormalities are suspected, expert assessment is recommended.

• Fat redistribution: May cause redistribution/accumulation of body fat (eg, central obesity, dorsocervical fat enlargement [buffalo hump], peripheral wasting, facial wasting, breast enlargement, cushingoid appearance).

• Hepatotoxicity: Hepatitis, including fulminant hepatitis sometimes fatal or progressing to liver failure requiring transplantation, has been reported in patients treated with efavirenz. Reports have included patients with underlying hepatic disease (including hepatitis B or C), but have also included patients without hepatic disease or other identifiable risk factors. Monitor liver function tests at baseline and during treatment in all patients.

• Hypercholesterolemia: Increases in total cholesterol and triglycerides have been reported with efavirenz; screening should be done prior to therapy and periodically throughout treatment.

• Immune reconstitution syndrome: Patients may develop immune reconstitution syndrome resulting in the occurrence of an inflammatory response to an indolent or residual opportunistic infection during initial HIV treatment or activation of autoimmune disorders (eg, Graves disease, polymyositis, Guillain-Barré syndrome, autoimmune hepatitis) later in therapy.

• Lactic acidosis/hepatomegaly: Lactic acidosis and severe hepatomegaly with steatosis, sometimes fatal, have been reported with use of nucleoside analogs and other antiretrovirals. Female gender and obesity may increase the risk for development. Suspend treatment in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (marked transaminase elevation may/may not accompany hepatomegaly and steatosis).

• Osteomalacia and renal dysfunction: Tenofovir disoproxil fumarate may cause osteomalacia with proximal renal tubulopathy. Bone pain, extremity pain, fractures, arthralgias, weakness, and muscle pain have been reported.

• Pancreatitis: Has been reported with lamivudine, particularly in HIV-infected pediatric patients with a history of antiretroviral nucleoside use, history of pancreatitis, or significant risk factors for pancreatitis. Discontinue treatment if signs of symptoms of pancreatitis occur.

• Psychiatric effects: Serious psychiatric symptoms have been associated with efavirenz, including severe depression, suicide attempts and ideation, paranoia, aggression, and mania. Use with caution in patients with a history of mental illness/drug abuse.

• QT prolongation: QT prolongation has been reported with efavirenz; consider alternative therapy in patients at risk of torsades de pointes or when coadministered with medications with known risk of torsades de pointes.

• Rash: Rash, ranging from mild to moderate maculopapular skin eruptions to life-threatening cutaneous reactions (eg, erythema multiforme, Stevens-Johnson syndrome), may occur with efavirenz. Mild to moderate rashes occur within 2 weeks (median onset: 11 days) and resolve within 1 month in most patients continuing treatment. Pediatric patients are more susceptible to development of rash (median time to onset: 28 days); prophylactic antihistamines should be considered.

• Renal toxicity: Tenofovir disoproxil fumarate may cause renal toxicity (including acute renal failure and/or Fanconi syndrome); avoid use with concurrent or recent nephrotoxic therapy (including high-dose or multiple nonsteroidal anti-inflammatory drug [NSAID] use). Acute renal failure has occurred in HIV-infected patients with risk factors for renal impairment who were on a stable tenofovir disoproxil fumarate regimen to which a high dose or multiple NSAID therapy was added. Consider alternatives to NSAIDs in patients taking tenofovir and at risk for renal impairment.

Disease-related concerns:

• Hepatic impairment: Not recommended in patients with moderate or severe hepatic impairment (Child-Pugh class B or C). Use caution in patients with mild hepatic impairment (Child-Pugh class A), including known or suspected hepatitis B or C infection; monitoring is recommended.

• HIV-associated dementia: Avoid efavirenz-based regimens if possible in patients with HIV-associated dementia; neuropsychiatric side effects of efavirenz may hinder assessment of the effects of antiretrovirals on the improvement of symptoms associated with HIV-associated dementia (HHS [adult] 2023).

• Renal impairment: Use is not recommended in patients with CrCl <50 mL/minute or patients with end-stage renal disease requiring hemodialysis.

• Seizure disorder: Use efavirenz with caution in patients with a history of seizure disorder; seizures have been associated with use.

Warnings: Additional Pediatric Considerations

Efavirenz may cause a rash, which usually presents as pruritic maculopapular skin eruptions; incidence is more common and more severe in children than in adults (incidence: children 32%, adults 26%; median onset: children: 28 days [range: 3 to 1,642 days], adults: 11 days). In adults, most rashes appeared within 14 days after starting therapy with a mean duration was 16 days. Rash may be treated with antihistamines and corticosteroids and usually resolves within 1 month while continuing efavirenz therapy. Discontinue efavirenz if severe rash (involving blistering, desquamation, mucosal involvement, ulceration, or fever) occurs. Consider prophylaxis with antihistamines in children due to frequency and severity of rash reported in children.

Neuropsychiatric effects due to efavirenz may also occur in pediatric patients. The overall reported incidence of CNS adverse effects was 53% (all patients) vs 25% in controls; neuropsychiatric symptoms in children receiving efavirenz were reported to be 14% in clinical studies and increased to 30% with efavirenz serum concentrations >4 mcg/mL (Puthanakit 2009; Shubber 2013). CNS adverse effects may be more difficult to detect in children because of the challenges assessing neurologic symptoms such as impaired concentration, sleep disturbances, or behavior disorders in these patients. Consider evaluation of efavirenz serum concentrations if CNS/neuropsychiatric adverse effects are persistent or severe; may require drug substitution if suitable alternative exists. Alternatively, consider dose reduction with monitoring of trough concentration and dose adjustment. One study reported an 11% incidence of new-onset seizures in children <36 months of age (HHS [pediatric] 2022).

The major clinical toxicity of lamivudine in pediatric patients is pancreatitis, which was reported in 14% of patients in one open-label, uncontrolled trial; discontinue lamivudine therapy if clinical signs, symptoms, or laboratory abnormalities suggestive of pancreatitis occur. Use with extreme caution and only if there is no satisfactory alternative therapy in pediatric patients with a history of pancreatitis or other significant risk factors for the development of pancreatitis.

Tenofovir disoproxil fumarate (TDF) disrupts vitamin D metabolism and has been associated with decreased bone mineral density (BMD) in adults and children. Plasma concentrations of the TDF metabolite tenofovir (TFV) have been associated with endocrine disruption and low BMD; tenofovir alafenamide (TAF) is associated with lower TFV concentrations and less decline in BMD than TDF. Data suggest the impact may be greater in children who are less mature (eg, Sexual Maturity Ratings [SMRs] 1 to 2 [previously Tanner Stages]) than in those with more advanced pubertal development (SMR ≥3). The potential for BMD loss during the important period of rapid bone accrual in childhood and early adolescence is concerning and favors use of abacavir or TAF in children with SMRs 1 to 3 (children with perinatally-acquired HIV are already at risk for low peak bone mass). The potential for BMD loss during the important period of rapid bone accrual in childhood and early adolescence is concerning and favors use of abacavir or TAF in children with SMRs 1 to 3 (children with perinatally acquired HIV are already at risk for low peak bone mass). Prior to initiation of therapy, assessment of benefits versus potential risk should be assessed; with TDF therapy, monitor plasma vitamin D concentrations; supplement with vitamin D as needed; calcium carbonate supplementation may also be considered. Monitoring of BMD may be considered in patients with additional risk factors for decreased bone density (HHS [pediatric] 2022).

Dosage Forms: US

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Symfi: Efavirenz 600 mg, lamivudine 300 mg, and tenofovir disoproxil fumarate 300 mg

Symfi Lo: Efavirenz 400 mg, lamivudine 300 mg, and tenofovir disoproxil fumarate 300 mg

Generic: Efavirenz 400 mg, lamivudine 300 mg, and tenofovir disoproxil fumarate 300 mg, Efavirenz 600 mg, lamivudine 300 mg, and tenofovir disoproxil fumarate 300 mg

Generic Equivalent Available: US

Yes

Pricing: US

Tablets (Efavirenz-lamiVUDine-Tenofovir Oral)

400-300-300 mg (per each): $57.53

600-300-300 mg (per each): $57.53

Tablets (Symfi Lo Oral)

400-300-300 mg (per each): $73.38

Tablets (Symfi Oral)

600-300-300 mg (per each): $73.38

Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.

Administration: Adult

Oral: Administer on an empty stomach, preferably at bedtime (may improve tolerability of CNS symptoms).

Administration: Pediatric

Oral: Administer on an empty stomach, preferably at bedtime (may improve tolerability of CNS symptoms).

Use: Labeled Indications

HIV-1 infection, treatment: Treatment of HIV-1 infection in adult and pediatric patients weighing ≥40 kg (Symfi) or ≥35 kg (Symfi Lo).

Metabolism/Transport Effects

Refer to individual components.

Drug Interactions

Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the Lexicomp drug interactions program by clicking on the “Launch drug interactions program” link above.

Abemaciclib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Abemaciclib. Risk X: Avoid combination

Abiraterone Acetate: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Abiraterone Acetate. Risk C: Monitor therapy

Acalabrutinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Acalabrutinib. Risk C: Monitor therapy

Acyclovir-Valacyclovir: May increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Acyclovir-Valacyclovir. Risk C: Monitor therapy

Adefovir: May diminish the therapeutic effect of Tenofovir Products. Adefovir may increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Adefovir. Risk X: Avoid combination

Alcohol (Ethyl): Efavirenz may enhance the adverse/toxic effect of Alcohol (Ethyl). Efavirenz may decrease the serum concentration of Alcohol (Ethyl). Risk C: Monitor therapy

ALfentanil: CYP3A4 Inducers (Moderate) may decrease the serum concentration of ALfentanil. Management: If concomitant use of alfentanil and moderate CYP3A4 inducers is necessary, consider dosage increase of alfentanil until stable drug effects are achieved. Monitor patients for signs of opioid withdrawal. Risk D: Consider therapy modification

ALPRAZolam: CYP3A4 Inducers (Moderate) may decrease the serum concentration of ALPRAZolam. Risk C: Monitor therapy

Aminoglycosides: May increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Aminoglycosides. Risk C: Monitor therapy

Aminosalicylic Acid: May decrease the serum concentration of Tenofovir Disoproxil Fumarate. Risk C: Monitor therapy

AmLODIPine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of AmLODIPine. Risk C: Monitor therapy

Amodiaquine: Efavirenz may enhance the hepatotoxic effect of Amodiaquine. Efavirenz may increase the serum concentration of Amodiaquine. Management: Avoid concurrent use of amodiaquine and efavirenz if possible. If such combination is unavoidable in the pursuit of prompt therapy, monitor closely for patient response and hepatotoxicity. Risk D: Consider therapy modification

Antihepaciviral Combination Products: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Antihepaciviral Combination Products. Risk X: Avoid combination

Apremilast: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Apremilast. Risk C: Monitor therapy

Aprepitant: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Aprepitant. Risk C: Monitor therapy

ARIPiprazole: CYP3A4 Inducers (Moderate) may decrease the serum concentration of ARIPiprazole. Risk C: Monitor therapy

ARIPiprazole Lauroxil: CYP3A4 Inducers (Moderate) may decrease the serum concentration of ARIPiprazole Lauroxil. Risk C: Monitor therapy

Artemether and Lumefantrine: Efavirenz may decrease serum concentrations of the active metabolite(s) of Artemether and Lumefantrine. Specifically, concentrations of dihydroartemisinin (DHA), the active metabolite of artemether may be decreased. Efavirenz may decrease the serum concentration of Artemether and Lumefantrine. Risk C: Monitor therapy

Asciminib: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Asunaprevir: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Asunaprevir. Risk X: Avoid combination

Atazanavir: Tenofovir Disoproxil Fumarate may decrease the serum concentration of Atazanavir. Atazanavir may increase the serum concentration of Tenofovir Disoproxil Fumarate. Management: Use boosted atazanavir in adults; give combo (atazanavir/ritonavir or atazanavir/cobicistat with tenofovir) as a single daily dose with food. Pediatric patients, pregnant patients, and use of H2-blockers require dose changes. See Lexi Interact monograph. Risk D: Consider therapy modification

Atazanavir: Efavirenz may decrease the serum concentration of Atazanavir. Management: Only use atazanavir/ritonavir (400/100 mg daily with food) an efavirenz (600 mg daily on empty stomach at bedtime) in treatment-naive patients. Use in treatment-experienced patients, or other combination of atazanavir and efavirenz, are not recommended. Risk D: Consider therapy modification

Atogepant: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Atogepant. Management: For treatment of episodic migraine, the recommended dose of atogepant is 30 mg once daily or 60 mg once daily when combined with CYP3A4 inducers. When used for treatment of chronic migraine, use of atogepant with CYP3A4 inducers should be avoided. Risk D: Consider therapy modification

Atorvastatin: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Atorvastatin. Risk C: Monitor therapy

Atovaquone: Efavirenz may decrease the serum concentration of Atovaquone. Management: Consider alternatives to the use of atovaquone with efavirenz when possible. If this combination must be used, monitor for evidence of reduced atovaquone clinical effectiveness. Risk D: Consider therapy modification

Avacopan: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Avacopan. Risk X: Avoid combination

Avanafil: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Avanafil. Risk X: Avoid combination

Avapritinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Avapritinib. Risk X: Avoid combination

Axitinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Axitinib. Risk X: Avoid combination

Bedaquiline: CYP3A4 Inducers (Moderate) may increase serum concentrations of the active metabolite(s) of Bedaquiline. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Bedaquiline. Risk X: Avoid combination

Belumosudil: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Belumosudil. Risk C: Monitor therapy

Benzhydrocodone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Benzhydrocodone. Specifically, the serum concentrations of hydrocodone may be reduced. Risk C: Monitor therapy

Betibeglogene Autotemcel: Antiretroviral Agents may diminish the therapeutic effect of Betibeglogene Autotemcel. Risk X: Avoid combination

Bictegravir: UGT1A1 Inducers may decrease the serum concentration of Bictegravir. Risk C: Monitor therapy

Bortezomib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Bortezomib. Risk C: Monitor therapy

Bosutinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Bosutinib. Risk C: Monitor therapy

Brexpiprazole: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Brexpiprazole. Risk C: Monitor therapy

Brigatinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Brigatinib. Management: Avoid concurrent use of brigatinib with moderate CYP3A4 inducers when possible. If combined, increase the daily dose of brigatinib in 30 mg increments after 7 days of treatment with the current brigatinib dose, up to maximum of twice the dose. Risk D: Consider therapy modification

Buprenorphine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Buprenorphine. Risk C: Monitor therapy

BuPROPion: CYP2B6 Inducers (Moderate) may decrease the serum concentration of BuPROPion. Risk C: Monitor therapy

BusPIRone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of BusPIRone. Risk C: Monitor therapy

Cabotegravir: UGT1A1 Inducers may decrease the serum concentration of Cabotegravir. Risk X: Avoid combination

Cabozantinib: MRP2 Inhibitors may increase the serum concentration of Cabozantinib. Risk C: Monitor therapy

Cabozantinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Cabozantinib. Risk C: Monitor therapy

Cannabis: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Cannabis. More specifically, tetrahydrocannabinol and cannabidiol serum concentrations may be decreased. Risk C: Monitor therapy

Capivasertib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Capivasertib. Risk X: Avoid combination

Capmatinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Capmatinib. Risk X: Avoid combination

CarBAMazepine: May decrease the serum concentration of Efavirenz. Efavirenz may decrease the serum concentration of CarBAMazepine. Risk X: Avoid combination

Cariprazine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Cariprazine. Risk X: Avoid combination

Caspofungin: Inducers of Drug Clearance may decrease the serum concentration of Caspofungin. Management: Consider using an increased caspofungin dose of 70 mg daily in adults (or 70 mg/m2, up to a maximum of 70 mg, daily in pediatric patients) when coadministered with known inducers of drug clearance. Risk D: Consider therapy modification

Ceritinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ceritinib. Risk C: Monitor therapy

Cidofovir: May increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Cidofovir. Risk C: Monitor therapy

Cladribine: Agents that Undergo Intracellular Phosphorylation may diminish the therapeutic effect of Cladribine. Risk X: Avoid combination

Clarithromycin: CYP3A4 Inducers (Moderate) may increase serum concentrations of the active metabolite(s) of Clarithromycin. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Clarithromycin. Management: Consider alternative antimicrobial therapy for patients receiving a CYP3A4 inducer. Drugs that enhance the metabolism of clarithromycin into 14-hydroxyclarithromycin may alter the clinical activity of clarithromycin and impair its efficacy. Risk D: Consider therapy modification

Clindamycin (Systemic): CYP3A4 Inducers (Moderate) may decrease the serum concentration of Clindamycin (Systemic). Risk C: Monitor therapy

CloZAPine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of CloZAPine. Risk C: Monitor therapy

Cobicistat: Tenofovir Disoproxil Fumarate may enhance the adverse/toxic effect of Cobicistat. More specifically, cobicistat may impair proper tenofovir disoproxil fumarate monitoring and dosing. Risk C: Monitor therapy

Cobimetinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Cobimetinib. Risk X: Avoid combination

Codeine: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Codeine. Risk C: Monitor therapy

Copanlisib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Copanlisib. Risk C: Monitor therapy

Crizotinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Crizotinib. Risk C: Monitor therapy

CycloPHOSphamide: CYP2B6 Inducers (Moderate) may increase serum concentrations of the active metabolite(s) of CycloPHOSphamide. Risk C: Monitor therapy

CycloSPORINE (Systemic): CYP3A4 Inducers (Moderate) may decrease the serum concentration of CycloSPORINE (Systemic). Risk C: Monitor therapy

CYP3A4 Inducers (Moderate): May decrease the serum concentration of Efavirenz. Risk C: Monitor therapy

CYP3A4 Inducers (Strong): May decrease the serum concentration of Efavirenz. Risk C: Monitor therapy

Daclatasvir: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Daclatasvir. Management: Increase the daclatasvir dose to 90 mg once daily if used with a moderate CYP3A4 inducer. Risk D: Consider therapy modification

Dapsone (Systemic): CYP3A4 Inducers (Moderate) may decrease the serum concentration of Dapsone (Systemic). Risk C: Monitor therapy

Daridorexant: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Daridorexant. Risk X: Avoid combination

Darolutamide: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Darunavir: May increase the serum concentration of Efavirenz. Efavirenz may decrease the serum concentration of Darunavir. Management: Monitor for decreased concentrations and effects of darunavir and/or increased concentrations and effects of efavirenz when darunavir/ritonavir is combined with efavirenz. The use of darunavir/cobicistat in combination with efavirenz is not recommended. Risk D: Consider therapy modification

Dasabuvir: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Dasabuvir. Risk X: Avoid combination

Dasatinib: CYP3A4 Inducers (Moderate) may increase the serum concentration of Dasatinib. Risk C: Monitor therapy

Deferasirox: UGT1A1 Inducers may decrease the serum concentration of Deferasirox. Management: Avoid concomitant use of deferasirox and UGT1A1 inducers when possible. If combined, consider a 50% increase in the initial deferasirox dose, with monitoring of serum ferritin concentrations and clinical response to guide further dosing. Risk D: Consider therapy modification

Deflazacort: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Deflazacort. Risk X: Avoid combination

DexAMETHasone (Systemic): CYP3A4 Inducers (Moderate) may decrease the serum concentration of DexAMETHasone (Systemic). Risk C: Monitor therapy

DiazePAM: CYP3A4 Inducers (Moderate) may decrease the serum concentration of DiazePAM. Risk C: Monitor therapy

Didanosine: Tenofovir Disoproxil Fumarate may diminish the therapeutic effect of Didanosine. Tenofovir Disoproxil Fumarate may increase the serum concentration of Didanosine. Management: Avoid use of tenofovir disoproxil fumarate and didanosine when possible. If combined in adults with CrCL greater than 60 mL/min, decrease didanosine to 250 mg daily if 60 kg or more or to 200 mg if less than 60 kg. Avoid if CrCL is less than 60 mL/min. Risk D: Consider therapy modification

Dienogest: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Dienogest. Risk C: Monitor therapy

DilTIAZem: CYP3A4 Inducers (Moderate) may decrease the serum concentration of DilTIAZem. Risk C: Monitor therapy

Disopyramide: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Disopyramide. Risk C: Monitor therapy

Dolutegravir: Efavirenz may decrease the serum concentration of Dolutegravir. Management: Increase dolutegravir to 50 mg twice/day in adults. Increase weight-based dose to twice daily in pediatric patients. Recommendations vary for combo products; see interaction monograph for details. Not recommended with Dovato or Juluca brand combos. Risk D: Consider therapy modification

DOXOrubicin (Conventional): CYP3A4 Inducers (Moderate) may decrease the serum concentration of DOXOrubicin (Conventional). Risk X: Avoid combination

DroNABinol: CYP3A4 Inducers (Moderate) may decrease the serum concentration of DroNABinol. Risk C: Monitor therapy

Dronedarone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Dronedarone. Risk C: Monitor therapy

Duvelisib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Duvelisib. Management: Avoid if possible. If used, on day 12 of combination increase duvelisib from 25 mg twice daily to 40 mg twice daily or from 15 mg twice daily to 25 mg twice daily. Resume prior duvelisib dose 14 days after stopping moderate CYP3A4 inducer. Risk D: Consider therapy modification

Dydrogesterone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Dydrogesterone. Risk C: Monitor therapy

Elacestrant: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Elacestrant. Risk X: Avoid combination

Elbasvir and Grazoprevir: Efavirenz may decrease the serum concentration of Elbasvir and Grazoprevir. Risk X: Avoid combination

Elexacaftor, Tezacaftor, and Ivacaftor: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Elexacaftor, Tezacaftor, and Ivacaftor. Risk C: Monitor therapy

Eliglustat: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Eliglustat. Risk C: Monitor therapy

Elivaldogene Autotemcel: Antiretroviral Agents may diminish the therapeutic effect of Elivaldogene Autotemcel. Management: Avoid use of antiretroviral medications for at least one month, or for the amount of time required for elimination of the retroviral medication, prior to stem cell mobilization and until the all apheresis cycles are finished Risk X: Avoid combination

Eltrombopag: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Elvitegravir: Efavirenz may decrease the serum concentration of Elvitegravir. Risk X: Avoid combination

Encorafenib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Encorafenib. Risk C: Monitor therapy

Encorafenib: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Entrectinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Entrectinib. Risk X: Avoid combination

Enzalutamide: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Enzalutamide. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Enzalutamide. Risk C: Monitor therapy

Erdafitinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Erdafitinib. Management: Dose modifications of erdafitinib may be required. See full monograph for details. Risk D: Consider therapy modification

Erdafitinib: May increase the serum concentration of OCT2 Substrates (Clinically Relevant with Inhibitors). Management: Consider alternatives to this combination when possible. If combined, monitor for increased effects/toxicities of OCT2 substrates and consider OCT2 substrate dose reductions when appropriate. Risk D: Consider therapy modification

Ergonovine: Reverse Transcriptase Inhibitors (Non-Nucleoside) may increase the serum concentration of Ergonovine. Specifically, this would be most likely with delavrdine, while other Non-Nucleoside Reverse Transcriptase Inhibitors may be more likely to decrease the concentration of Ergonovine. Risk X: Avoid combination

Erlotinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Erlotinib. Risk C: Monitor therapy

Estrogen Derivatives: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Estrogen Derivatives. Risk C: Monitor therapy

Etoposide: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Etoposide. Risk C: Monitor therapy

Etoposide Phosphate: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Etoposide Phosphate. Risk C: Monitor therapy

Everolimus: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Everolimus. Risk C: Monitor therapy

Exemestane: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Exemestane. Risk C: Monitor therapy

Fedratinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Fedratinib. Risk X: Avoid combination

Felodipine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Felodipine. Risk C: Monitor therapy

FentaNYL: CYP3A4 Inducers (Moderate) may decrease the serum concentration of FentaNYL. Risk C: Monitor therapy

Fexinidazole: CYP3A4 Inducers (Moderate) may increase serum concentrations of the active metabolite(s) of Fexinidazole. Risk X: Avoid combination

Finerenone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Finerenone. Risk X: Avoid combination

Flibanserin: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Flibanserin. Risk X: Avoid combination

Fosamprenavir: Efavirenz may decrease serum concentrations of the active metabolite(s) of Fosamprenavir. Management: For once-daily fosamprenavir/ritonavir with efavirenz, increase ritonavir dose to 300 mg/day in adult patients. No ritonavir dose adjustment is required if using twice-daily fosamprenavir/ritonavir. Risk D: Consider therapy modification

Fosaprepitant: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Fosaprepitant. Specifically, CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite aprepitant. Risk C: Monitor therapy

Foslevodopa: May increase the serum concentration of MATE1/2-K Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Fosnetupitant: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Fosnetupitant. Risk C: Monitor therapy

Fosphenytoin-Phenytoin: May decrease the serum concentration of Efavirenz. Efavirenz may decrease the serum concentration of Fosphenytoin-Phenytoin. Risk C: Monitor therapy

Fostamatinib: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Fostamatinib. Risk C: Monitor therapy

Fruquintinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Fruquintinib. Management: Avoid this combination when possible. If combined, continue the same fruquintinib dose, but monitor for reduced fruquintinib efficacy. Risk D: Consider therapy modification

Futibatinib: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Ganaxolone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ganaxolone. Management: Avoid concomitant use of ganaxolone and moderate CYP3A4 inducers whenever possible. If combined, consider increasing the dose of ganaxolone, but do not exceed the maximum recommended daily dose. Risk D: Consider therapy modification

Ganciclovir-Valganciclovir: Tenofovir Products may increase the serum concentration of Ganciclovir-Valganciclovir. Ganciclovir-Valganciclovir may increase the serum concentration of Tenofovir Products. Risk C: Monitor therapy

Gefitinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Gefitinib. Risk C: Monitor therapy

Gemigliptin: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Gemigliptin. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Gemigliptin. Risk C: Monitor therapy

Gepirone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Gepirone. Risk C: Monitor therapy

Gilteritinib: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Gilteritinib: May increase the serum concentration of OCT1 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Ginkgo Biloba: May decrease the serum concentration of Efavirenz. Risk C: Monitor therapy

Glasdegib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Glasdegib. Management: Avoid use of glasdegib and moderate CYP3A4 inducers whenever possible. If combined, increase glasdegib dose from 100 mg daily to 200 mg daily or from 50 mg daily to 100 mg daily. Resume previous glasdegib dose 7 days after discontinuation of the inducer. Risk D: Consider therapy modification

Glecaprevir and Pibrentasvir: Efavirenz may decrease the serum concentration of Glecaprevir and Pibrentasvir. Risk X: Avoid combination

GuanFACINE: CYP3A4 Inducers (Moderate) may decrease the serum concentration of GuanFACINE. Management: Increase extended-release guanfacine dose by up to double when initiating guanfacine in patients taking CYP3A4 inducers or if initiating a CYP3A4 inducer in a patient already taking extended-release guanfacine. Monitor for reduced guanfacine efficacy. Risk D: Consider therapy modification

Haloperidol: QT-prolonging Agents (Indeterminate Risk - Avoid) may enhance the QTc-prolonging effect of Haloperidol. Risk C: Monitor therapy

Hormonal Contraceptives: Efavirenz may decrease the serum concentration of Hormonal Contraceptives. Management: Use a back-up method during coadministration, and to continue back-up contraception for 12 weeks after stopping efavirenz to ensure contraceptive reliability. Injected depot medroxyprogesterone acetate does not appear to participate in this interaction. Risk D: Consider therapy modification

Horsetail: May diminish the therapeutic effect of Efavirenz. Risk C: Monitor therapy

HYDROcodone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of HYDROcodone. Risk C: Monitor therapy

Hydrocortisone (Systemic): CYP3A4 Inducers (Moderate) may decrease the serum concentration of Hydrocortisone (Systemic). Risk C: Monitor therapy

Ibrexafungerp: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ibrexafungerp. Risk X: Avoid combination

Ibrutinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ibrutinib. Risk C: Monitor therapy

Idelalisib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Idelalisib. Risk C: Monitor therapy

Ifosfamide: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Ifosfamide. CYP3A4 Inducers (Moderate) may increase serum concentrations of the active metabolite(s) of Ifosfamide. Risk C: Monitor therapy

Imatinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Imatinib. Risk C: Monitor therapy

Indinavir: Efavirenz may decrease the serum concentration of Indinavir. Management: The appropriate dose adjustments for indinavir when used together with efavirenz are unknown. The use of higher unboosted indinavir doses is not likely an adequate approach. Use of a ritonavir-boosted indinavir regimen could be considered. Risk D: Consider therapy modification

Infigratinib: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Infigratinib. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Infigratinib. Risk X: Avoid combination

Irinotecan Products: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Irinotecan Products. Specifically, concentrations of SN-38 may be reduced. Risk C: Monitor therapy

Isavuconazonium Sulfate: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Isavuconazonium Sulfate. Specifically, CYP3A4 Inducers (Moderate) may decrease isavuconazole serum concentrations. Risk C: Monitor therapy

Isradipine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Isradipine. Risk C: Monitor therapy

Istradefylline: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Istradefylline. Risk C: Monitor therapy

Itraconazole: Efavirenz may decrease serum concentrations of the active metabolite(s) of Itraconazole. Efavirenz may decrease the serum concentration of Itraconazole. Risk X: Avoid combination

Ivabradine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ivabradine. Risk X: Avoid combination

Ivacaftor: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ivacaftor. Risk C: Monitor therapy

Ixabepilone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ixabepilone. Risk C: Monitor therapy

Ixazomib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ixazomib. Risk C: Monitor therapy

Ketamine: CYP2B6 Inducers (Moderate) may decrease the serum concentration of Ketamine. Risk C: Monitor therapy

Ketoconazole (Systemic): Efavirenz may decrease the serum concentration of Ketoconazole (Systemic). Management: The use of ketoconazole concurrently with or within 2 weeks of efavirenz is not recommended. If such a combination cannot be avoided, monitor patients closely for evidence of diminished clinical response to ketoconazole. Risk D: Consider therapy modification

Lapatinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Lapatinib. Risk C: Monitor therapy

Larotrectinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Larotrectinib. Management: Double the larotrectinib dose if used together with a moderate CYP3A4 inducer. Following discontinuation of the moderate CYP3A4 inducer, resume the previous dose of larotrectinib after a period of 3 to 5 times the inducer's half-life. Risk D: Consider therapy modification

Ledipasvir: May increase the serum concentration of Tenofovir Disoproxil Fumarate. Management: Avoid this combination if TDF is used as part of the elvitegravir/cobicistat/emtricitabine/TDF product. Consider alternatives when TDF is used with a ritonavir or cobicistat boosted protease inhibitor. Monitor for increased TDF toxicities if combined. Risk D: Consider therapy modification

Lefamulin: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Lefamulin. Management: Avoid concomitant use of lefamulin with moderate CYP3A4 inducers unless the benefits outweigh the risks. Risk D: Consider therapy modification

Lefamulin (Intravenous): CYP3A4 Inducers (Moderate) may decrease the serum concentration of Lefamulin (Intravenous). Management: Avoid concomitant use of lefamulin (intravenous) with moderate CYP3A4 inducers unless the benefits outweigh the risks. Risk D: Consider therapy modification

Leflunomide: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Lemborexant: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Lemborexant. Risk X: Avoid combination

Lenacapavir: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Lenacapavir. Risk X: Avoid combination

Leniolisib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Leniolisib. Risk X: Avoid combination

Leniolisib: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk X: Avoid combination

Lercanidipine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Lercanidipine. Risk C: Monitor therapy

Letermovir: UGT1A1 Inducers may decrease the serum concentration of Letermovir. Risk X: Avoid combination

Levamlodipine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Levamlodipine. Risk C: Monitor therapy

Levoketoconazole: Efavirenz may decrease the serum concentration of Levoketoconazole. Risk X: Avoid combination

Levomethadone: Reverse Transcriptase Inhibitors (Non-Nucleoside) may decrease the serum concentration of Levomethadone. Management: Levomethadone dosage adjustments will likely be required with efavirenz and nevirapine, and may be necessary with rilpivirine as well. Risk C: Monitor therapy

Levomethadone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Levomethadone. Risk C: Monitor therapy

LinaGLIPtin: CYP3A4 Inducers (Moderate) may decrease the serum concentration of LinaGLIPtin. Risk C: Monitor therapy

Lonafarnib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Lonafarnib. Risk X: Avoid combination

Lopinavir: Efavirenz may decrease the serum concentration of Lopinavir. Management: Avoid once daily use of lopinavir/ritonavir with efavirenz. Avoid use of this combination in patients less than 6 months of age. Lopinavir/ritonavir dose adjustments are required for patients taking twice daily lopinavir/ritonavir. See full monograph. Risk D: Consider therapy modification

Lorlatinib: CYP3A4 Inducers (Moderate) may enhance the hepatotoxic effect of Lorlatinib. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Lorlatinib. Management: Avoid use of lorlatinib with moderate CYP3A4 inducers. If such a combination must be used, increase lorlatinib to 125 mg daily. Monitor for reduced lorlatinib efficacy and consider closer monitoring of AST, ALT, and bilirubin. Risk D: Consider therapy modification

Lovastatin: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Lovastatin. Risk C: Monitor therapy

Lovotibeglogene Autotemcel: Antiretroviral Agents may diminish the therapeutic effect of Lovotibeglogene Autotemcel. Risk X: Avoid combination

Lumacaftor and Ivacaftor: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Lumacaftor and Ivacaftor. Risk C: Monitor therapy

Lumacaftor and Ivacaftor: May increase the serum concentration of P-glycoprotein/ABCB1 Substrates (High risk with Inhibitors or Inducers). Lumacaftor and Ivacaftor may decrease the serum concentration of P-glycoprotein/ABCB1 Substrates (High risk with Inhibitors or Inducers). Risk C: Monitor therapy

Lumateperone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Lumateperone. Risk X: Avoid combination

Lurasidone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Lurasidone. Management: Monitor for decreased lurasidone effects if combined with moderate CYP3A4 inducers and consider increasing the lurasidone dose if coadministered with a moderate CYP3A4 inducer for 7 or more days. Risk D: Consider therapy modification

Macimorelin: Efavirenz may diminish the diagnostic effect of Macimorelin. Risk C: Monitor therapy

Macitentan: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Macitentan. Risk C: Monitor therapy

Maraviroc: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Maraviroc. Management: Increase maraviroc adult dose to 600 mg twice/day, but only if not receiving a strong CYP3A4 inhibitor. Not recommended for pediatric patients not also receiving a strong CYP3A4 inhibitor. Contraindicated in patients with CrCl less than 30 mL/min. Risk D: Consider therapy modification

Maribavir: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Maribavir. Risk C: Monitor therapy

Mavacamten: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Mavacamten. Risk X: Avoid combination

Mefloquine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Mefloquine. Risk C: Monitor therapy

Meperidine: CYP2B6 Inducers (Moderate) may increase serum concentrations of the active metabolite(s) of Meperidine. Specifically, concentrations of normeperidine, the CNS stimulating metabolite, may be increased. CYP2B6 Inducers (Moderate) may decrease the serum concentration of Meperidine. Risk C: Monitor therapy

Methadone: Reverse Transcriptase Inhibitors (Non-Nucleoside) may increase the metabolism of Methadone. Management: Methadone dosage adjustments will likely be required with efavirenz and nevirapine, and may be necessary with rilpivirine as well. Risk C: Monitor therapy

MethylPREDNISolone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of MethylPREDNISolone. Risk C: Monitor therapy

Mianserin: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Mianserin. Risk C: Monitor therapy

Midazolam: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Midazolam. Risk C: Monitor therapy

Midostaurin: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Midostaurin. Risk C: Monitor therapy

MiFEPRIStone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of MiFEPRIStone. Management: Avoid combined use in patients treated for Cushing's disease. When used for pregnancy termination, mifepristone efficacy may be reduced and an alternative pregnancy termination procedure may be warranted. Ensure a follow-up assessment after combined use. Risk D: Consider therapy modification

Mirodenafil: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Mirodenafil. Risk C: Monitor therapy

Mitapivat: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Mitapivat. Management: Consider alternatives to this combination when possible. If combined, monitor hemoglobin and titrate mitapivat beyond 50 mg twice daily, if needed, but do not exceed doses of 100 mg twice daily. Risk D: Consider therapy modification

Mobocertinib: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Mobocertinib. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Mobocertinib. Risk X: Avoid combination

Naldemedine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Naldemedine. Risk C: Monitor therapy

Naloxegol: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Naloxegol. Risk C: Monitor therapy

Nelfinavir: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Nelfinavir. Risk C: Monitor therapy

Neratinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Neratinib. Risk X: Avoid combination

Netupitant: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Netupitant. Risk C: Monitor therapy

NIFEdipine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of NIFEdipine. Risk C: Monitor therapy

Nilotinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Nilotinib. Risk C: Monitor therapy

Nilvadipine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Nilvadipine. Risk C: Monitor therapy

NiMODipine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of NiMODipine. Risk C: Monitor therapy

Nirmatrelvir and Ritonavir: Efavirenz may enhance the adverse/toxic effect of Nirmatrelvir and Ritonavir. Efavirenz may decrease the serum concentration of Nirmatrelvir and Ritonavir. Specifically, efavirenz may decrease concentration of nirmatrelvir. Efavirenz may increase the serum concentration of Nirmatrelvir and Ritonavir. Specifically, efavirenz may increase concentration of ritonavir. Nirmatrelvir and Ritonavir may increase the serum concentration of Efavirenz. Risk C: Monitor therapy

Nirogacestat: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Nirogacestat. Risk X: Avoid combination

Nisoldipine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Nisoldipine. Risk X: Avoid combination

Nonsteroidal Anti-Inflammatory Agents: May enhance the nephrotoxic effect of Tenofovir Products. Management: Seek alternatives to these combinations whenever possible. Avoid use of tenofovir with multiple NSAIDs or any NSAID given at a high dose due to a potential risk of acute renal failure. Diclofenac appears to confer the most risk. Risk D: Consider therapy modification

Nonsteroidal Anti-Inflammatory Agents (Topical): May enhance the nephrotoxic effect of Tenofovir Products. Risk C: Monitor therapy

Olaparib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Olaparib. Risk X: Avoid combination

Oliceridine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Oliceridine. Risk C: Monitor therapy

Olmutinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Olmutinib. Risk C: Monitor therapy

Olutasidenib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Olutasidenib. Risk X: Avoid combination

Omaveloxolone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Omaveloxolone. Risk X: Avoid combination

Orelabrutinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Orelabrutinib. Risk X: Avoid combination

Orlistat: May decrease the serum concentration of Antiretroviral Agents. Risk C: Monitor therapy

Osimertinib: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Osimertinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Osimertinib. Risk C: Monitor therapy

Oteseconazole: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

OxyCODONE: CYP3A4 Inducers (Moderate) may decrease the serum concentration of OxyCODONE. Risk C: Monitor therapy

PACLitaxel (Conventional): CYP3A4 Inducers (Moderate) may decrease the serum concentration of PACLitaxel (Conventional). Risk C: Monitor therapy

PACLitaxel (Protein Bound): CYP3A4 Inducers (Moderate) may decrease the serum concentration of PACLitaxel (Protein Bound). Risk C: Monitor therapy

Pacritinib: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk X: Avoid combination

Pacritinib: May increase the serum concentration of OCT1 Substrates (Clinically Relevant with Inhibitors). Risk X: Avoid combination

Pacritinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Pacritinib. Risk X: Avoid combination

Palbociclib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Palbociclib. Risk C: Monitor therapy

Palovarotene: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Palovarotene. Risk X: Avoid combination

PAZOPanib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of PAZOPanib. Risk C: Monitor therapy

Pemigatinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Pemigatinib. Risk X: Avoid combination

Perampanel: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Perampanel. Management: Increase perampanel starting dose to 4 mg/day if used with moderate CYP3A4 inducers. Increase perampanel dose by 2 mg/day no more than once weekly based on response and tolerability. Dose adjustments may be needed if the inducer is discontinued. Risk D: Consider therapy modification

P-glycoprotein/ABCB1 Inhibitors: May increase the serum concentration of Tenofovir Disoproxil Fumarate. Risk C: Monitor therapy

Pimavanserin: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Pimavanserin. Risk X: Avoid combination

Piperaquine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Piperaquine. Risk C: Monitor therapy

Pirtobrutinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Pirtobrutinib. Management: Avoid concomitant use if possible. If combined, if the current pirtobrutinib dose is 200 mg once daily, increase to 300 mg once daily. If current pirtobrutinib dose is 50 mg or 100 mg once daily, increase the dose by 50 mg. Risk D: Consider therapy modification

PONATinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of PONATinib. Risk C: Monitor therapy

Posaconazole: Efavirenz may decrease the serum concentration of Posaconazole. Risk X: Avoid combination

Pralsetinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Pralsetinib. Management: If this combo cannot be avoided, increase pralsetinib dose from 400 mg daily to 600 mg daily; from 300 mg daily to 500 mg daily; and from 200 mg daily to 300 mg daily. Risk D: Consider therapy modification

Pravastatin: Efavirenz may decrease the serum concentration of Pravastatin. Risk C: Monitor therapy

Praziquantel: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Praziquantel. Management: Consider alternatives to this combination whenever possible. If combined, monitor closely for reduced praziquantel efficacy. If possible, stop the moderate CYP3A4 inducer 2 to 4 weeks before praziquantel initiation. Risk D: Consider therapy modification

PrednisoLONE (Systemic): CYP3A4 Inducers (Moderate) may decrease the serum concentration of PrednisoLONE (Systemic). Risk C: Monitor therapy

PredniSONE: CYP3A4 Inducers (Moderate) may decrease the serum concentration of PredniSONE. Risk C: Monitor therapy

Pretomanid: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Pretomanid. Risk X: Avoid combination

Proguanil: Efavirenz may decrease serum concentrations of the active metabolite(s) of Proguanil. Efavirenz may decrease the serum concentration of Proguanil. Efavirenz may increase the serum concentration of Proguanil. Risk C: Monitor therapy

QT-prolonging Agents (Highest Risk): QT-prolonging Agents (Indeterminate Risk - Avoid) may enhance the QTc-prolonging effect of QT-prolonging Agents (Highest Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy

QUEtiapine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of QUEtiapine. Risk C: Monitor therapy

QuiNIDine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of QuiNIDine. Risk C: Monitor therapy

QuiNINE: CYP3A4 Inducers (Moderate) may decrease the serum concentration of QuiNINE. Risk C: Monitor therapy

Quizartinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Quizartinib. Risk X: Avoid combination

Ranolazine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ranolazine. Risk X: Avoid combination

Red Yeast Rice: Efavirenz may decrease the serum concentration of Red Yeast Rice. Risk C: Monitor therapy

Regorafenib: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Regorafenib: CYP3A4 Inducers (Moderate) may increase serum concentrations of the active metabolite(s) of Regorafenib. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Regorafenib. Risk C: Monitor therapy

Repaglinide: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Repaglinide. Risk C: Monitor therapy

Repotrectinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Repotrectinib. Risk X: Avoid combination

Reverse Transcriptase Inhibitors (Non-Nucleoside): May enhance the adverse/toxic effect of other Reverse Transcriptase Inhibitors (Non-Nucleoside). Reverse Transcriptase Inhibitors (Non-Nucleoside) may decrease the serum concentration of other Reverse Transcriptase Inhibitors (Non-Nucleoside). Specifically, efavirenz and nevirapine may decrease the serum concentrations of other non-nucleoside reverse transcriptase inhibitors. Reverse Transcriptase Inhibitors (Non-Nucleoside) may increase the serum concentration of other Reverse Transcriptase Inhibitors (Non-Nucleoside). Specifically, delavirdine may increase the serum concentration of etravirine. Risk X: Avoid combination

Ribociclib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ribociclib. Risk C: Monitor therapy

Rifabutin: Efavirenz may decrease the serum concentration of Rifabutin. Rifabutin may decrease the serum concentration of Efavirenz. Management: If efavirenz is to be used with daily rifabutin, increase the planned rifabutin dose by 50% to a dose of 450 mg to 600 mg daily. If used with regimens where rifabutin is administered 2 to 3 times per week, consider doubling the rifabutin dose. Risk D: Consider therapy modification

RifAMPin: May decrease the serum concentration of Efavirenz. Efavirenz may decrease the serum concentration of RifAMPin. Management: Monitor for reduced response to efavirenz and rifampin. Guidelines suggest no efavirenz dose adjustments are required when combined, while labeling recommends an efavirenz dose increase to 800 mg daily in adults weighing more than 50 kg. Risk C: Monitor therapy

Rimegepant: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Rimegepant. Risk X: Avoid combination

Ripretinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ripretinib. Management: Avoid this combination if possible. If concomitant use is required, increase ripretinib to 150 mg twice daily. Decrease ripretinib to 150 mg once daily 14 days after stopping a moderate CYP3A4 inducer. Monitor patients for ripretinib response and toxicity Risk D: Consider therapy modification

Risdiplam: May increase the serum concentration of MATE1/2-K Substrates (Clinically Relevant with Inhibitors). Management: Avoid use of risdiplam with MATE substrates if possible. If the combination cannot be avoided, monitor closely for adverse effects. Consider a reduced dose of the MATE substrate according to that substrate's labeling if appropriate. Risk D: Consider therapy modification

RisperiDONE: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of RisperiDONE. CYP3A4 Inducers (Moderate) may decrease the serum concentration of RisperiDONE. Risk C: Monitor therapy

Ritlecitinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ritlecitinib. Risk C: Monitor therapy

Ritonavir: Efavirenz may enhance the adverse/toxic effect of Ritonavir. Efavirenz may increase the serum concentration of Ritonavir. Ritonavir may increase the serum concentration of Efavirenz. Risk C: Monitor therapy

Roflumilast (Systemic): CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Roflumilast (Systemic). CYP3A4 Inducers (Moderate) may decrease the serum concentration of Roflumilast (Systemic). Risk C: Monitor therapy

Rolapitant: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Rolapitant. Risk C: Monitor therapy

Rolapitant: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Management: Monitor patients receiving rolapitant for increased exposure to and/or effects of BCRP/ABCG2 substrates. Use the lowest effective rosuvastatin dose when used in combination with rolapitant. Risk C: Monitor therapy

Sacituzumab Govitecan: UGT1A1 Inducers may decrease serum concentrations of the active metabolite(s) of Sacituzumab Govitecan. Specifically, concentrations of SN-38 may be decreased. Risk X: Avoid combination

Samidorphan: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Samidorphan. Risk C: Monitor therapy

Saquinavir: May enhance the hepatotoxic effect of Efavirenz. Efavirenz may decrease the serum concentration of Saquinavir. Management: When used together with efavirenz, saquinavir should not be used as the sole protease inhibitor. Appropriate doses of the combination of efavirenz with saquinavir/ritonavir have not been established. Risk X: Avoid combination

Selpercatinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Selpercatinib. Risk X: Avoid combination

Selumetinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Selumetinib. Risk X: Avoid combination

Sertraline: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Sertraline. Risk C: Monitor therapy

Sildenafil: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Sildenafil. Risk C: Monitor therapy

Simeprevir: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Simeprevir. Risk X: Avoid combination

Simvastatin: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Simvastatin. Risk C: Monitor therapy

Sirolimus (Conventional): CYP3A4 Inducers (Moderate) may decrease the serum concentration of Sirolimus (Conventional). Risk C: Monitor therapy

Sirolimus (Protein Bound): CYP3A4 Inducers (Moderate) may decrease the serum concentration of Sirolimus (Protein Bound). Risk C: Monitor therapy

Sonidegib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Sonidegib. Risk X: Avoid combination

SORAfenib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of SORAfenib. Risk C: Monitor therapy

Sorbitol: May decrease the serum concentration of LamiVUDine. Management: When possible, avoid chronic coadministration of sorbitol-containing solutions with lamivudine, but if this combination cannot be avoided, monitor patients more closely for possible therapeutic failure associated with decreased lamivudine exposure. Risk D: Consider therapy modification

Sotorasib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Sotorasib. Risk C: Monitor therapy

Sparsentan: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk X: Avoid combination

SUFentanil: CYP3A4 Inducers (Moderate) may decrease the serum concentration of SUFentanil. Risk C: Monitor therapy

SUNItinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of SUNItinib. Risk C: Monitor therapy

Suvorexant: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Suvorexant. Risk C: Monitor therapy

Tacrolimus (Systemic): CYP3A4 Inducers (Moderate) may decrease the serum concentration of Tacrolimus (Systemic). Risk C: Monitor therapy

Tacrolimus (Systemic): Tenofovir Products may enhance the nephrotoxic effect of Tacrolimus (Systemic). Risk C: Monitor therapy

Tadalafil: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Tadalafil. Risk C: Monitor therapy

Tafamidis: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Tafenoquine: May increase the serum concentration of MATE1/2-K Substrates (Clinically Relevant with Inhibitors). Management: Avoid use of MATE substrates with tafenoquine, and if the combination cannot be avoided, monitor closely for evidence of toxicity of the MATE substrate and consider a reduced dose of the MATE substrate according to that substrate's labeling. Risk D: Consider therapy modification

Tafenoquine: May increase the serum concentration of OCT2 Substrates (Clinically Relevant with Inhibitors). Management: Avoid use of OCT2 substrates with tafenoquine, and if the combination cannot be avoided, monitor closely for evidence of toxicity of the OCT2 substrate and consider a reduced dose of the OCT2 substrate according to that substrate's labeling. Risk D: Consider therapy modification

Tamoxifen: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Tamoxifen. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Tamoxifen. Risk C: Monitor therapy

Tasimelteon: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Tasimelteon. Risk C: Monitor therapy

Taurursodiol: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk X: Avoid combination

Tazemetostat: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Tazemetostat. Risk X: Avoid combination

Tedizolid: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Temsirolimus: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Temsirolimus. Specifically, sirolimus concentrations may be decreased. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Temsirolimus. Risk C: Monitor therapy

Teriflunomide: May increase the serum concentration of BCRP/ABCG2 Substrates (Clinically Relevant with Inhibitors). Risk C: Monitor therapy

Tetrahydrocannabinol: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Tetrahydrocannabinol. Risk C: Monitor therapy

Tetrahydrocannabinol and Cannabidiol: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Tetrahydrocannabinol and Cannabidiol. Risk C: Monitor therapy

Tezacaftor and Ivacaftor: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Tezacaftor and Ivacaftor. Risk C: Monitor therapy

Thiotepa: May increase the serum concentration of CYP2B6 Substrates (High risk with Inhibitors). Risk C: Monitor therapy

Thiotepa: CYP3A4 Inducers (Moderate) may increase serum concentrations of the active metabolite(s) of Thiotepa. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Thiotepa. Risk C: Monitor therapy

Ticagrelor: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Ticagrelor. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ticagrelor. Risk C: Monitor therapy

Tipranavir: Tenofovir Disoproxil Fumarate may decrease the serum concentration of Tipranavir. Tipranavir may decrease the serum concentration of Tenofovir Disoproxil Fumarate. Risk C: Monitor therapy

Tivozanib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Tivozanib. Risk C: Monitor therapy

Tofacitinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Tofacitinib. Risk C: Monitor therapy

Tolvaptan: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Tolvaptan. Risk C: Monitor therapy

Toremifene: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Toremifene. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Toremifene. Risk C: Monitor therapy

Trabectedin: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Trabectedin. Risk C: Monitor therapy

TraMADol: CYP3A4 Inducers (Moderate) may decrease the serum concentration of TraMADol. Risk C: Monitor therapy

TraZODone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of TraZODone. Risk C: Monitor therapy

Triazolam: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Triazolam. Risk C: Monitor therapy

Trimethoprim: May increase the serum concentration of LamiVUDine. Risk C: Monitor therapy

Tucatinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Tucatinib. Risk C: Monitor therapy

Ubrogepant: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ubrogepant. Management: Use an initial ubrogepant dose of 100 mg and second dose (if needed) of 100 mg when used with a moderate CYP3A4 inducer. Risk D: Consider therapy modification

Ulipristal: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Ulipristal. Risk X: Avoid combination

Upadacitinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Upadacitinib. Risk C: Monitor therapy

Valbenazine: CYP3A4 Inducers (Moderate) may decrease serum concentrations of the active metabolite(s) of Valbenazine. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Valbenazine. Risk C: Monitor therapy

Valoctocogene Roxaparvovec: May enhance the hepatotoxic effect of Efavirenz. Efavirenz may diminish the therapeutic effect of Valoctocogene Roxaparvovec. Risk X: Avoid combination

Vandetanib: CYP3A4 Inducers (Moderate) may increase serum concentrations of the active metabolite(s) of Vandetanib. CYP3A4 Inducers (Moderate) may decrease the serum concentration of Vandetanib. Risk C: Monitor therapy

Velpatasvir: CYP2B6 Inducers (Moderate) may decrease the serum concentration of Velpatasvir. Risk X: Avoid combination

Velpatasvir: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Velpatasvir. Risk X: Avoid combination

Vemurafenib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Vemurafenib. Risk C: Monitor therapy

Venetoclax: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Venetoclax. Risk X: Avoid combination

Verapamil: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Verapamil. Risk C: Monitor therapy

Vilazodone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Vilazodone. Risk C: Monitor therapy

Vitamin K Antagonists (eg, warfarin): Efavirenz may decrease the serum concentration of Vitamin K Antagonists. Efavirenz may increase the serum concentration of Vitamin K Antagonists. Risk C: Monitor therapy

Voclosporin: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Voclosporin. Risk X: Avoid combination

Vonoprazan: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Vonoprazan. Risk X: Avoid combination

Vorapaxar: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Vorapaxar. Risk X: Avoid combination

Voriconazole: Efavirenz may decrease the serum concentration of Voriconazole. Voriconazole may increase the serum concentration of Efavirenz. Management: Use of standard doses of these drugs is contraindicated. The voriconazole oral maintenance dose should be increased to 400 mg every 12 hours, and the efavirenz dose should be reduced to 300 mg daily. Risk D: Consider therapy modification

Vortioxetine: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Vortioxetine. Risk C: Monitor therapy

Voxelotor: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Voxelotor. Management: Avoid concomitant use of voxelotor and moderate CYP3A4 inducers. If unavoidable, increase the voxelotor dose to 2,000 mg once daily. For children ages 4 to less than 12 years, weight-based dose adjustments are required. See full monograph for details. Risk D: Consider therapy modification

Voxilaprevir: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Voxilaprevir. Risk X: Avoid combination

Zaleplon: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Zaleplon. Risk C: Monitor therapy

Zanubrutinib: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Zanubrutinib. Management: Avoid this combination if possible. If coadministration of zanubrutinib and a moderate CYP3A4 inducer is required, increase the zanubrutinib dose to 320 mg twice daily. Risk D: Consider therapy modification

Zolpidem: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Zolpidem. Risk C: Monitor therapy

Zopiclone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Zopiclone. Risk C: Monitor therapy

Zuranolone: CYP3A4 Inducers (Moderate) may decrease the serum concentration of Zuranolone. Risk X: Avoid combination

Food Interactions

High-fat/high-caloric meals increase the absorption of efavirenz. CNS effects are possible. Management: Administer at or before bedtime on an empty stomach.

Reproductive Considerations

The manufacturer's labeling recommends pregnancy testing prior to therapy and effective contraception (including a barrier method) in patients who may become pregnant during treatment and for 12 weeks after therapy is discontinued. However, current Health and Human Services (HHS) perinatal HIV guidelines note contraception is not required to initiate or continue antiretroviral therapy (ART). Patients with HIV not planning to become pregnant may use any available type of contraception, considering possible drug interactions and contraindications of the specific method. Consult drug interactions database for more detailed information specific to use of this combination and specific contraceptives.

The Health and Human Services perinatal HIV guidelines consider this fixed-dose combination an alternative regimen for patients with HIV who are not yet pregnant but are trying to conceive (HHS [perinatal] 2023).

Refer to individual monographs for additional information.

Pregnancy Considerations

The Health and Human Services perinatal HIV guidelines consider this fixed-dose combination an alternative regimen for pregnant patients with HIV who are antiretroviral-naive, who have had antiretroviral therapy (ART) in the past but are restarting, or who require a new ART regimen (due to poor tolerance or poor virologic response of current regimen). In addition, patients who become pregnant while taking this fixed-dose combination may continue if viral suppression is effective and the regimen is well tolerated. This fixed dose combination may be considered for patients when significant drug interactions would occur with preferred agents or in patients who need the convenience of a co-formulated single dose tablet in a once daily regimen but are not eligible for preferred agents (HHS [perinatal] 2023).

Refer to individual monographs for additional information.

Breastfeeding Considerations

Efavirenz, lamivudine, and tenofovir are present in breast milk.

Refer to individual monographs for additional information.

Dietary Considerations

Consider calcium and vitamin D supplementation.

Monitoring Parameters

Testing for HBV is recommended prior to the initiation of antiretroviral therapy. CD4 count, HIV RNA plasma levels; serum creatinine, serum phosphorus, estimated creatinine clearance, urine glucose, urine protein, total cholesterol, and triglycerides (prior to initiation and as clinically indicated during therapy); hepatic function tests at baseline and during therapy; bone density (patients with a history of bone fracture or have risk factors for bone loss or osteoporosis). In patients at risk for renal dysfunction, persistent or worsening bone or muscle symptoms should be evaluated for hypophosphatemia and osteomalacia.

Monitor for rash. Monitor for signs and symptoms of serious neurologic adverse effects and consider discontinuation of therapy.

Patients with HIV and HBV coinfection should have hepatic function monitored for several months following discontinuation.

Mechanism of Action

Efavirenz: Non-nucleoside reverse transcriptase inhibitor of HIV-1. It consequently blocks the RNA-dependent and DNA-dependent DNA polymerase activities including HIV-1 replication.

Lamivudine: Cytosine analog that is phosphorylated intracellularly to its active 5”-triphosphate metabolite. The principle mode of action is inhibition of HIV reverse transcription via viral DNA chain termination; inhibits RNA- and DNA-dependent DNA polymerase activities of reverse transcriptase.

Tenofovir disoproxil fumarate: Nucleotide reverse transcriptase inhibitor; analog of adenosine 5' monophosphate that interferes with the HIV viral RNA dependent DNA polymerase resulting in inhibition of viral replication. TDF is first converted intracellularly by hydrolysis to tenofovir and subsequently phosphorylated to the active tenofovir diphosphate. Tenofovir inhibits replication of HBV by inhibiting HBV polymerase.

Pharmacokinetics (Adult Data Unless Noted)

Refer to individual monographs.

  1. Lucas GM, Ross MJ, Stock PG, et al. Clinical practice guideline for the management of chronic kidney disease in patients infected with HIV: 2014 update by the HIV Medicine Association of the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(9): e96-138. doi:10.1093/cid/ciu617 [PubMed 25234519]
  2. Puthanakit T, Tanpaiboon P, Aurpibul L, Cressey TR, Sirisanthana V. Plasma efavirenz concentrations and the association with CYP2B6-516G >T polymorphism in HIV-infected Thai children. Antivir Ther. 2009;14(3):315-320. [PubMed 19474465]
  3. Shubber Z, Calmy A, Andrieux-Meyer I, et al. Adverse events associated with nevirapine and efavirenz-based first-line antiretroviral therapy: a systematic review and meta-analysis. AIDS. 2013;27(9):1403-1412. [PubMed 23343913]
  4. Symfi (efavirenz/lamivudine/tenofovir disoproxil fumarate) [prescribing information]. Morgantown, WV: Mylan Specialty LP; May 2019.
  5. Symfi Lo (efavirenz/lamivudine/tenofovir disoproxil fumarate) [prescribing information]. Morgantown, WV: Mylan Specialty LP; October 2019.
  6. US Department of Health and Human Services (HHS) Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in adults and adolescents with HIV, Department of Health and Human Services. https://clinicalinfo.hiv.gov/sites/default/files/guidelines/documents/adult-adolescent-arv/guidelines-adult-adolescent-arv.pdf. Updated March 23, 2023. Accessed September 6, 2023.
  7. US Department of Health and Human Services (HHS) Panel on Antiretroviral Therapy and Medical Management of Children Living with HIV. Guidelines for the use of antiretroviral agents in pediatric HIV infection. https://clinicalinfo.hiv.gov/sites/default/files/guidelines/documents/pediatric-arv/guidelines-pediatric-arv.pdf. Updated April 11, 2022. Accessed July 7, 2022.
  8. US Department of Health and Human Services (HHS) Panel on Treatment of HIV During Pregnancy and Prevention of Perinatal Transmission. Recommendations for the use of antiretroviral drugs during pregnancy and interventions to reduce perinatal HIV transmission in the United States. https://clinicalinfo.hiv.gov/en/guidelines/perinatal/whats-new. Updated January 31, 2023. Accessed February 23, 2023.
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