Version July 2025
Dosage guidance:
Dosage form information: Lexiva oral suspension has been discontinued in the United States for >1 year.
HIV-1 infection, treatment: Oral:
Antiretroviral therapy-naive patients:
Note: Fosamprenavir is not recommended as a component of initial therapy for the treatment of HIV (Ref).
Unboosted regimen: 1.4 g twice daily (without ritonavir).
Ritonavir-boosted regimens:
Once-daily regimen: Fosamprenavir 1.4 g once daily plus ritonavir 100 to 200 mg once daily.
Twice-daily regimen: Fosamprenavir 700 twice daily plus ritonavir 100 mg twice daily.
Protease inhibitor-experienced patients: Fosamprenavir 700 mg twice daily plus ritonavir 100 mg twice daily. Note: Once-daily administration is not recommended in protease inhibitor-experienced patients.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustments provided in the manufacturer's labeling (has not been studied); however, dosage adjustment unlikely due to minimal (eg, 1%) renal elimination of unchanged amprenavir.
Mild impairment (Child-Pugh class A): Reduce dosage of fosamprenavir to 700 mg twice daily without concurrent ritonavir (therapy naive) or fosamprenavir 700 mg twice daily plus ritonavir 100 mg once daily (therapy naive or PI experienced).
Moderate impairment (Child-Pugh class B): Reduce dosage of fosamprenavir to 700 mg twice daily without concurrent ritonavir (therapy naive) or fosamprenavir 450 mg twice daily plus ritonavir 100 mg once daily (therapy naive or PI experienced).
Severe impairment (Child-Pugh class C): Reduce dosage of fosamprenavir to 350 mg twice daily without concurrent ritonavir (therapy naive) or fosamprenavir 300 mg twice daily plus ritonavir 100 mg once daily (therapy naive or PI experienced).
Refer to adult dosing.
(For additional information see "Fosamprenavir: Pediatric drug information")
Dosage guidance:
Dosage form information: Lexiva oral suspension has been discontinued in the United States for >1 year.
Clinical considerations: Evaluate gene mutation and antiretroviral (ARV) resistance patterns (refer to https://www.iasusa.org/ and https://hivdb.stanford.edu/ for more information).
HIV-1 infection, treatment: Note: Although FDA approved, fosamprenavir is no longer recommended for use in pediatric patients due to low exposure levels (Ref). If used, it should be in combination with other ARV agents. Do not administer fosamprenavir (with or without ritonavir) to protease inhibitor-experienced pediatric patients <6 months of age. In addition, once-daily dosing of fosamprenavir (with or without ritonavir) is not recommended in any pediatric patient (Ref).
Protease inhibitor-naive patients:
Ritonavir unboosted regimen: Children ≥2 years and Adolescents: Note: Manufacturer labeling may not reflect current practice. Oral: 30 mg/kg/dose twice daily; maximum dose 1,400 mg/dose.
Ritonavir-boosted regimen: Infants, Children, and Adolescents: Note: Manufacturer labeling may not reflect current practice. Per the manufacturer, use only in infants born at ≥38 weeks GA and who are at least 28 days PNA; however, experts recommend to avoid use in infants <6 months due to low systemic exposure (Ref): Oral:
<11 kg: Fosamprenavir 45 mg/kg/dose plus ritonavir 7 mg/kg/dose twice daily.
11 to <15 kg: Fosamprenavir 30 mg/kg/dose plus ritonavir 3 mg/kg/dose twice daily.
15 to <20 kg: Fosamprenavir 23 mg/kg/dose plus ritonavir 3 mg/kg/dose twice daily.
≥20 kg: Fosamprenavir 18 mg/kg/dose (maximum dose: 700 mg/dose) twice daily plus ritonavir 3 mg/kg/dose (maximum dose: 100 mg/dose) twice daily.
Protease inhibitor-experienced: Ritonavir-boosted regimen: Note: Manufacturer labeling may not reflect current practice. Infants ≥6 months, Children, and Adolescents: Oral:
<11 kg: Fosamprenavir 45 mg/kg/dose plus ritonavir 7 mg/kg/dose twice daily.
11 to <15 kg: Fosamprenavir 30 mg/kg/dose plus ritonavir 3 mg/kg/dose twice daily.
15 to <20 kg: Fosamprenavir 23 mg/kg/dose plus ritonavir 3 mg/kg/dose twice daily.
≥20 kg: Fosamprenavir 18 mg/kg/dose (maximum dose: 700 mg/dose) twice daily plus ritonavir 3 mg/kg/dose twice daily (maximum dose: 100 mg/dose) twice daily.
Note: When combined with ritonavir, fosamprenavir tablets may be administered to children who weigh ≥39 kg.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Infants, Children, and Adolescents: No dosage adjustment necessary (Ref).
There are no pediatric specific dosage adjustments provided in the manufacturer's labeling (has not been studied); based on experience in adult patients, dosing adjustment is suggested.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
>10%:
Dermatologic: Skin rash (≤19%; onset: ~11 days; duration: ~13 days)
Endocrine & metabolic: Hypertriglyceridemia (>750 mg/dL: ≤11%)
Gastrointestinal: Diarrhea (5% to 13%; moderate-to-severe)
1% to 10%:
Central nervous system: Fatigue (2% to 4%; moderate-to-severe), headache (2% to 4%; moderate-to-severe)
Dermatologic: Pruritus (7% to 8%)
Endocrine & metabolic: Hyperglycemia (>251 mg/dL: ≤2%)
Gastrointestinal: Increased serum lipase (>2x ULN: 5% to 8%), nausea (3% to 7%; moderate-to-severe), vomiting (2% to 6%; moderate-to-severe), abdominal pain (≤2%; moderate-to-severe)
Hematologic & oncologic: Neutropenia (<750 cells/mm3: 3%)
Hepatic: Increased serum transaminases (>5x ULN: 4% to 8%)
<1%, postmarketing, and/or case reports: Angioedema, cerebrovascular accident, hypercholesterolemia, myocardial infarction, nephrolithiasis, oral paresthesia, Stevens-Johnson syndrome
Clinically significant hypersensitivity (eg, Stevens-Johnson syndrome) to fosamprenavir, amprenavir, or any component of the formulation; coadministration with drugs highly dependent on CYP3A4 for clearance and for which elevated plasma concentrations are associated with serious and/or life-threatening events (eg, alfuzosin, rifampin, ergot derivatives [eg, dihydroergotamine, ergonovine, ergotamine, methylergonovine], cisapride, St. John's wort, lovastatin, lomitapide, simvastatin, pimozide, delavirdine, sildenafil [when used for treatment of pulmonary arterial hypertension], midazolam, or triazolam); use of flecainide, lurasidone, or propafenone with concomitant ritonavir therapy.
Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Also refer to the ritonavir monograph, if used in combination with ritonavir, for additional contraindications.
Canadian labeling: Additional contraindications (not in US labeling): Coadministration with antihistamines, GI motility agents, amiodarone, diazepam, flurazepam, lidocaine (systemic), quetiapine.
Concerns related to adverse effects:
• Body fat increase: May cause an increase in body fat.
• Hemolytic anemia: Acute hemolytic anemia has been reported in association with amprenavir use.
• Hepatic effects: May cause transaminase elevations, hepatitis, and/or exacerbate preexisting hepatic dysfunction; use with caution in patients with underlying hepatic disease, such as hepatitis B or C or cirrhosis.
• Hypersensitivity reactions: Protease inhibitors have been associated with a variety of hypersensitivity events (some severe), including rash, anaphylaxis (rare), angioedema, bronchospasm, erythema multiforme, and/or Stevens-Johnson syndrome (rare). It is generally recommended to discontinue treatment if severe rash or moderate symptoms accompanied by other systemic symptoms occur.
• 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) later in therapy; further evaluation and treatment may be required.
• Lipid elevations: Increases in total cholesterol and triglycerides have been reported; screening should be done prior to therapy and periodically throughout treatment.
• Nephrolithiasis: Cases have been reported in postmarketing surveillance; temporary or permanent discontinuation of therapy should be considered if symptoms develop.
• Sulfonamide allergy: Use with caution in patients with sulfonamide allergy. In clinical trials, the incidence of rash did not differ appreciably in patients with or without a history of sulfonamide allergy.
Disease-related concerns:
• Diabetes: Changes in glucose tolerance, hyperglycemia, exacerbation of diabetes, diabetic ketoacidosis, and new-onset diabetes mellitus have been reported in patients receiving protease inhibitors.
• Hemophilia A or B: Use with caution in patients with hemophilia A or B; increased bleeding during protease inhibitor therapy has been reported.
• Hepatic impairment: Use with caution; dosage adjustment required.
Special populations:
• Protease inhibitor-experienced adults: Once-daily fosamprenavir/ritonavir is not recommended in protease inhibitor-experienced adults.
Dosage forms specific issues:
• Polysorbate 80: Some dosage forms may contain polysorbate 80 (also known as Tweens). Hypersensitivity reactions, usually a delayed reaction, have been reported following exposure to pharmaceutical products containing polysorbate 80 in certain individuals (Isaksson 2002; Lucente 2000; Shelley 1995). Thrombocytopenia, ascites, pulmonary deterioration, and renal and hepatic failure have been reported in premature neonates after receiving parenteral products containing polysorbate 80 (Alade 1986; CDC 1984).
• Propylene glycol: Some dosage forms may contain propylene glycol; large amounts are potentially toxic and have been associated with hyperosmolality, lactic acidosis, seizures, and respiratory depression; use caution (AAP 1997; Zar 2007).
Some dosage forms may contain propylene glycol; in neonates, large amounts of propylene glycol delivered orally, intravenously (eg, >3,000 mg/day), or topically have been associated with potentially fatal toxicities which can include metabolic acidosis, seizures, renal failure, and CNS depression; toxicities have also been reported in children and adults including hyperosmolality, lactic acidosis, seizures, and respiratory depression; use caution (AAP 1997; Shehab 2009).
Lexiva oral suspension has been discontinued in the United States for >1 year.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Suspension, Oral, as calcium:
Lexiva: 50 mg/mL (225 mL [DSC]) [contains methylparaben, polysorbate 80, propylene glycol, propylparaben; grape bubblegum peppermint flavor]
Tablet, Oral, as calcium:
Lexiva: 700 mg [DSC]
Generic: 700 mg
May be product dependent
Tablets (Fosamprenavir Calcium Oral)
700 mg (per each): $20.83
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.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Suspension, Oral, as calcium:
Telzir: 50 mg/mL ([DSC]) [contains methylparaben, polysorbate 80, propylene glycol, propylparaben]
Tablet, Oral, as calcium:
Telzir: 700 mg [DSC]
Oral suspension: Administer without food. Readminister dose of suspension if emesis occurs within 30 minutes after dosing. Shake suspension vigorously prior to use.
Tablet: Administer with food if taken with ritonavir. May be administered without regard to food if not taken with ritonavir.
Oral: Do not administer concurrently with antacids or buffered formulations of other medications (separate administration by 1 hour).
Oral suspension: Administer with food. Readminister dose of suspension if emesis occurs within 30 minutes after dosing. Shake suspension vigorously prior to use.
Tablets: Administer with food to pediatric patients.
HIV-1 infection, treatment: Treatment of HIV-1 infection, in combination with other antiretroviral agents. Note: Fosamprenavir is not recommended as a component of initial therapy for the treatment of HIV (HHS [ARV adult] 2023).
Lexiva may be confused with Levitra, Pexeva
Substrate of CYP2C9 (Minor), CYP2D6 (Minor), CYP3A4 (Major), P-glycoprotein (Minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential; Inhibits CYP3A4 (Moderate);
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 drug interactions program by clicking on the “Launch drug interactions program” link above.
Abemaciclib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Abemaciclib. Management: Monitor for increased abemaciclib toxicities if combined with moderate CYP3A4 inhibitors. Consider reducing the abemaciclib dose in 50 mg decrements if necessary. Risk C: Monitor
Acalabrutinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Acalabrutinib. Management: Reduce acalabrutinib dose to 100 mg once daily with concurrent use of a moderate CYP3A4 inhibitor. Monitor patient closely for both acalabrutinib response and evidence of adverse effects with any concurrent use. Risk D: Consider Therapy Modification
Acrivastine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Acrivastine. Risk C: Monitor
ALfentanil: CYP3A4 Inhibitors (Moderate) may increase serum concentration of ALfentanil. Management: If use of alfentanil and moderate CYP3A4 inhibitors is necessary, consider dosage reduction of alfentanil until stable drug effects are achieved. Frequently monitor patients for respiratory depression and sedation when these agents are combined. Risk D: Consider Therapy Modification
Alfuzosin: Fosamprenavir may increase serum concentration of Alfuzosin. Risk X: Avoid
Alitretinoin (Systemic): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Alitretinoin (Systemic). Risk C: Monitor
ALPRAZolam: CYP3A4 Inhibitors (Moderate) may increase serum concentration of ALPRAZolam. Management: Consider alternatives to this combination when possible. If combined, consider an alprazolam dose reduction and monitor for increased alprazolam effects and toxicities (eg, sedation, lethargy). Risk D: Consider Therapy Modification
Amiodarone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Amiodarone. Risk C: Monitor
AmLODIPine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of AmLODIPine. Risk C: Monitor
Antidiabetic Agents: Hyperglycemia-Associated Agents may decrease therapeutic effects of Antidiabetic Agents. Risk C: Monitor
Apixaban: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Apixaban. Risk C: Monitor
Aprepitant: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Aprepitant. Risk X: Avoid
ARIPiprazole Lauroxil: CYP3A4 Inhibitors (Moderate) may increase serum concentration of ARIPiprazole Lauroxil. Risk C: Monitor
ARIPiprazole: CYP3A4 Inhibitors (Moderate) may increase serum concentration of ARIPiprazole. Management: Monitor for increased aripiprazole pharmacologic effects. Aripiprazole dose adjustments may or may not be required based on concomitant therapy, indication, or dosage form. Consult full interaction monograph for specific recommendations. Risk C: Monitor
Artemether and Lumefantrine: Protease Inhibitors may increase serum concentration of Artemether and Lumefantrine. Specifically, the concentrations of lumefantrine may be increased. Protease Inhibitors may decrease serum concentration of Artemether and Lumefantrine. Specifically, concentrations of artemether and dihydroartemisinin (DHA), the active metabolite of artemether, may be decreased. Risk C: Monitor
Atazanavir: Fosamprenavir may decrease serum concentration of Atazanavir. Atazanavir may increase active metabolite exposure of Fosamprenavir. Management: Consider alternatives to this combination. Safe and effective doses of fosamprenavir and atazanavir have not been established for concurrent use. Risk D: Consider Therapy Modification
Atidarsagene Autotemcel: Antiretroviral Agents may decrease therapeutic effects of Atidarsagene Autotemcel. Risk X: Avoid
Atogepant: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Atogepant. Risk C: Monitor
Atorvastatin: Fosamprenavir may increase serum concentration of Atorvastatin. Atorvastatin may increase active metabolite exposure of Fosamprenavir. Management: Use the lowest atorvastatin dose necessary and limit the atorvastatin dose to 20 mg daily in patients taking fosamprenavir. Monitor patients for signs and symptoms of myopathy at initiation of therapy and with any dose increase. Risk D: Consider Therapy Modification
Avacopan: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Avacopan. Risk C: Monitor
Avanafil: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Avanafil. Management: The maximum avanafil dose is 50 mg per 24-hour period when used together with a moderate CYP3A4 inhibitor. Patients receiving such a combination should also be monitored more closely for evidence of adverse effects (eg, hypotension, syncope, priapism). Risk D: Consider Therapy Modification
Avapritinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Avapritinib. Management: Avoid use of moderate CYP3A4 inhibitors with avapritinib. If this combination cannot be avoided, reduce the avapritinib dose to 100 mg daily for the treatment of GIST or to 50 mg daily for the treatment of advanced systemic mastocytosis. Risk D: Consider Therapy Modification
Axitinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Axitinib. Risk C: Monitor
Barnidipine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Barnidipine. Risk C: Monitor
Bedaquiline: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Bedaquiline. CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of Bedaquiline. Risk C: Monitor
Benidipine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Benidipine. Risk C: Monitor
Benzhydrocodone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Benzhydrocodone. Specifically, the concentration of hydrocodone may be increased. Risk C: Monitor
Betibeglogene Autotemcel: Antiretroviral Agents may decrease therapeutic effects of Betibeglogene Autotemcel. Risk X: Avoid
Blonanserin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Blonanserin. Risk C: Monitor
Bortezomib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Bortezomib. Risk C: Monitor
Bosentan: Protease Inhibitors may increase serum concentration of Bosentan. Management: Dose adjustment of bosentan and increased monitoring for bosentan toxicities is necessary when these agents are combined. See full drug interaction monograph for details. Risk D: Consider Therapy Modification
Bosutinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Bosutinib. Risk X: Avoid
Brexpiprazole: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Brexpiprazole. Management: The brexpiprazole dose should be reduced to 25% of usual if used together with both a moderate CYP3A4 inhibitor and a strong or moderate CYP2D6 inhibitor, or if a moderate CYP3A4 inhibitor is used in a CYP2D6 poor metabolizer. Risk C: Monitor
Brigatinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Brigatinib. Management: Avoid concurrent use of brigatinib with moderate CYP3A4 inhibitors when possible. If such a combination cannot be avoided, reduce the dose of brigatinib by approximately 40% (ie, from 180 mg to 120 mg, from 120 mg to 90 mg, or from 90 mg to 60 mg). Risk D: Consider Therapy Modification
Bromocriptine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Bromocriptine. Management: The bromocriptine dose should not exceed 1.6 mg daily with use of a moderate CYP3A4 inhibitor. The Cycloset brand specifically recommends this dose limitation, but other bromocriptine products do not make such specific recommendations. Risk D: Consider Therapy Modification
Budesonide (Oral Inhalation): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Budesonide (Oral Inhalation). Risk C: Monitor
Budesonide (Systemic): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Budesonide (Systemic). Management: Avoid the concomitant use of CYP3A4 inhibitors and oral budesonide. If patients receive both budesonide and CYP3A4 inhibitors, they should be closely monitored for signs and symptoms of corticosteroid excess. Risk D: Consider Therapy Modification
Budesonide (Topical): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Budesonide (Topical). Risk X: Avoid
Buprenorphine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Buprenorphine. Risk C: Monitor
BusPIRone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of BusPIRone. Risk C: Monitor
Cabozantinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Cabozantinib. Risk C: Monitor
Cannabis: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Cannabis. More specifically, tetrahydrocannabinol and cannabidiol serum concentrations may be increased. Risk C: Monitor
Capivasertib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Capivasertib. Management: If capivasertib is combined with moderate CYP3A4 inhibitors, reduce the capivasertib dose to 320 mg twice daily for 4 days, followed by 3 days off. Monitor patients closely for adverse reactions. Risk D: Consider Therapy Modification
CarBAMazepine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of CarBAMazepine. Risk C: Monitor
Cariprazine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Cariprazine. CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of Cariprazine. Management: Cariprazine dose adjustments are recommended and depend upon whether a patient is initiating a moderate CYP3A4 inhibitor or cariprazine, as well as cariprazine indication. See full mono for details. Some non-US labels contraindicate this combination. Risk D: Consider Therapy Modification
Ceritinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ceritinib. Risk C: Monitor
Cilostazol: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Cilostazol. Management: Decrease the dose of cilostazol to 50 mg twice daily when combined with moderate CYP3A4 inhibitors. Risk D: Consider Therapy Modification
Cisapride: Fosamprenavir may increase serum concentration of Cisapride. Risk X: Avoid
Clarithromycin: Protease Inhibitors may increase serum concentration of Clarithromycin. Protease Inhibitors may decrease active metabolite exposure of Clarithromycin. Management: Do not exceed clarithromycin doses greater than 1,000 mg/day in patients taking protease inhibitors. If CrCL is 30 to 60 mL/min, reduced clarithromycin dose 50%. If CrCL is less than 30 mL/min, reduced clarithromycin dose 75%. Risk D: Consider Therapy Modification
Clindamycin (Systemic): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Clindamycin (Systemic). Risk C: Monitor
Clofazimine: May increase serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Risk C: Monitor
Clorazepate: Fosamprenavir may increase serum concentration of Clorazepate. Risk C: Monitor
CloZAPine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of CloZAPine. Risk C: Monitor
Cobicistat: May increase serum concentration of Fosamprenavir. However, the magnitude of this change is unclear, and dosing recommendations for this combination are not available. Risk X: Avoid
Cobimetinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Cobimetinib. Management: Avoid this combination when possible. If concurrent short term (14 days or less) use cannot be avoided, reduce the cobimetinib dose from 60 mg to 20 mg daily. Avoid concomitant use in patients already receiving reduced cobimetinib doses. Risk D: Consider Therapy Modification
Codeine: CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of Codeine. Risk C: Monitor
Colchicine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Colchicine. Management: Avoidance, dose reduction, or increased monitoring for colchicine toxicity may be needed and will depend on brand, indication for colchicine use, renal/hepatic function, and use of a P-gp inhibitor. See full monograph for details. Risk D: Consider Therapy Modification
Conivaptan: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Conivaptan. Risk C: Monitor
Copanlisib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Copanlisib. Risk C: Monitor
Crizotinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Crizotinib. Risk C: Monitor
CycloPHOSphamide: Protease Inhibitors may increase adverse/toxic effects of CycloPHOSphamide. Specifically, the incidences of neutropenia, infection, and mucositis may be increased. Protease Inhibitors may increase serum concentration of CycloPHOSphamide. Risk C: Monitor
CycloSPORINE (Systemic): CYP3A4 Inhibitors (Moderate) may increase serum concentration of CycloSPORINE (Systemic). Risk C: Monitor
CYP3A4 Inducers (Moderate): May decrease active metabolite exposure of Fosamprenavir. Risk C: Monitor
CYP3A4 Inducers (Strong): May decrease active metabolite exposure of Fosamprenavir. Risk C: Monitor
CYP3A4 Inhibitors (Moderate): May increase serum concentration of Fosamprenavir. Risk C: Monitor
CYP3A4 Inhibitors (Strong): May increase serum concentration of Fosamprenavir. Risk C: Monitor
Dabrafenib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Dabrafenib. Risk C: Monitor
Dapoxetine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Dapoxetine. Management: The dose of dapoxetine should be limited to 30 mg per day when used together with a moderate inhibitor of CYP3A4. Risk D: Consider Therapy Modification
Daridorexant: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Daridorexant. Management: Limit the daridorexant dose to 25 mg, no more than once per night, when combined with moderate CYP3A4 inhibitors. Risk D: Consider Therapy Modification
Darifenacin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Darifenacin. Risk C: Monitor
Darunavir: Protease Inhibitors may decrease serum concentration of Darunavir. Protease Inhibitors may increase serum concentration of Darunavir. Risk X: Avoid
Dasatinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Dasatinib. Risk C: Monitor
Deflazacort: CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of Deflazacort. Management: Administer one third of the recommended deflazacort dose when used together with a strong or moderate CYP3A4 inhibitor. Risk D: Consider Therapy Modification
Delamanid: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Delamanid. Risk C: Monitor
DexAMETHasone (Systemic): May decrease serum concentration of Fosamprenavir. Fosamprenavir may increase serum concentration of DexAMETHasone (Systemic). Risk C: Monitor
DiazePAM: CYP3A4 Inhibitors (Moderate) may increase serum concentration of DiazePAM. Risk C: Monitor
Diazoxide Choline: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Diazoxide Choline. Risk C: Monitor
Dienogest: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Dienogest. Risk C: Monitor
DilTIAZem: CYP3A4 Inhibitors (Moderate) may increase serum concentration of DilTIAZem. Risk C: Monitor
Disopyramide: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Disopyramide. Risk C: Monitor
DOCEtaxel: CYP3A4 Inhibitors (Moderate) may increase serum concentration of DOCEtaxel. Risk C: Monitor
Dofetilide: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Dofetilide. Risk C: Monitor
Dolutegravir: Fosamprenavir may decrease serum concentration of Dolutegravir. Specifically, Fosamprenavir/Ritonavir may decrease the serum concentration of Dolutegravir. The individual contributions of Fosamprenavir and Ritonavir to this effect are unknown. 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
Domperidone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Domperidone. Risk X: Avoid
DOXOrubicin (Conventional): CYP3A4 Inhibitors (Moderate) may increase serum concentration of DOXOrubicin (Conventional). Risk X: Avoid
DroNABinol: CYP3A4 Inhibitors (Moderate) may increase serum concentration of DroNABinol. Risk C: Monitor
Dronedarone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Dronedarone. Risk C: Monitor
Ebastine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ebastine. Risk C: Monitor
Efavirenz: May decrease active metabolite exposure 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
Elacestrant: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Elacestrant. Risk X: Avoid
Elbasvir and Grazoprevir: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Elbasvir and Grazoprevir. Risk C: Monitor
Eletriptan: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Eletriptan. Risk X: Avoid
Elexacaftor, Tezacaftor, and Ivacaftor: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Elexacaftor, Tezacaftor, and Ivacaftor. Management: When combined with moderate CYP3A4 inhibitors, elexacaftor/tezacaftor/ivacaftor should be given in the morning, every other day. Ivacaftor alone should be given in the morning, every other day on alternate days. Risk D: Consider Therapy Modification
Eliglustat: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Eliglustat. Management: Reduce eliglustat dose to 84 mg daily in CYP2D6 EMs when used with moderate CYP3A4 inhibitors. Avoid use of moderate CYP3A4 inhibitors in CYP2D6 IMs or PMs. Use in CYP2D6 EMs or IMs also taking strong or moderate CYP2D6 inhibitors is contraindicated. Risk D: Consider Therapy Modification
Elivaldogene Autotemcel: Antiretroviral Agents may decrease therapeutic effects 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
Encorafenib: Fosamprenavir may increase serum concentration of Encorafenib. Encorafenib may decrease serum concentration of Fosamprenavir. Management: Avoid use of encorafenib and fosamprenavir when possible. If combined, decrease the encorafenib dose from 450 mg to 225 mg; 300 mg to 150 mg; and 225 mg or 150 mg to 75 mg. Monitor for reduced fosamprenavir efficacy. Risk D: Consider Therapy Modification
Ensartinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ensartinib. Risk X: Avoid
Entrectinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Entrectinib. Management: Avoid moderate CYP3A4 inhibitors if possible. If needed, reduce entrectinib dose to 50 mg/day if starting dose 200 mg; to 100 mg/day if starting dose 300 mg; to 200 mg if starting dose 400 mg or 600 mg. Risk D: Consider Therapy Modification
Eplerenone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Eplerenone. Management: If coadministered with moderate CYP3A4 inhibitors, the max dose of eplerenone is 25 mg daily if used for heart failure; if used for hypertension initiate eplerenone 25 mg daily, titrate to max 25 mg twice daily. Risk D: Consider Therapy Modification
Ergot Derivatives (Vasoconstrictive CYP3A4 Substrates): Fosamprenavir may increase serum concentration of Ergot Derivatives (Vasoconstrictive CYP3A4 Substrates). Risk X: Avoid
Erlotinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Erlotinib. Risk C: Monitor
Erythromycin (Systemic): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Erythromycin (Systemic). Risk C: Monitor
Estrogen Derivatives: Protease Inhibitors may decrease serum concentration of Estrogen Derivatives. Protease Inhibitors may increase serum concentration of Estrogen Derivatives. Risk C: Monitor
Eszopiclone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Eszopiclone. Risk C: Monitor
Etravirine: May increase active metabolite exposure of Fosamprenavir. Specifically, amprenavir concentrations may increase. Risk X: Avoid
Everolimus: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Everolimus. Risk C: Monitor
Fedratinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Fedratinib. Risk C: Monitor
Felodipine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Felodipine. Risk C: Monitor
FentaNYL: CYP3A4 Inhibitors (Moderate) may increase serum concentration of FentaNYL. Management: Consider fentanyl dose reductions when combined with a moderate CYP3A4 inhibitor. Monitor for respiratory depression and sedation. Upon discontinuation of a CYP3A4 inhibitor, consider a fentanyl dose increase; monitor for signs and symptoms of withdrawal. Risk D: Consider Therapy Modification
Fexinidazole: CYP3A4 Inhibitors (Moderate) may decrease active metabolite exposure of Fexinidazole. Management: Avoid use of fexinidazole and moderate CYP3A4 inhibitors when possible. If combined, monitor for reduced fexinidazole efficacy. Risk D: Consider Therapy Modification
Finerenone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Finerenone. Risk C: Monitor
Flibanserin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Flibanserin. Management: Use of flibanserin with moderate CYP3A4 inhibitors is contraindicated. If starting flibanserin, start 2 weeks after the last dose of the CYP3A4 inhibitor. If starting a CYP3A4 inhibitor, start 2 days after the last dose of flibanserin. Risk X: Avoid
Flurazepam: Fosamprenavir may increase serum concentration of Flurazepam. Risk C: Monitor
Fluticasone (Nasal): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Fluticasone (Nasal). Risk C: Monitor
Fluticasone (Oral Inhalation): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Fluticasone (Oral Inhalation). Risk C: Monitor
Fosaprepitant: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Fosaprepitant. Risk X: Avoid
Fosphenytoin: May decrease serum concentration of Fosamprenavir. Fosamprenavir may decrease serum concentration of Fosphenytoin. Specifically, fosamprenavir boosted with ritonavir may decrease phenytoin concentrations. Risk C: Monitor
Fusidic Acid (Systemic): May increase serum concentration of Protease Inhibitors. Protease Inhibitors may increase serum concentration of Fusidic Acid (Systemic). Management: Avoid this combination if possible, due to the risk of increased concentrations of both agents which increases the risk of hepatotoxicity. If combined, monitor patients closely for adverse effects of both agents. Risk D: Consider Therapy Modification
Garlic: May decrease serum concentration of Protease Inhibitors. Risk X: Avoid
Gepirone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Gepirone. Management: Reduce the gepirone dose by 50% if combined with moderate CYP3A4 inhibitors. Monitor for QTc interval prolongation with combined use. Risk D: Consider Therapy Modification
Gepotidacin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Gepotidacin. Risk C: Monitor
Gilteritinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Gilteritinib. Risk C: Monitor
Glasdegib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Glasdegib. Risk C: Monitor
Grapefruit Juice: May increase serum concentration of Fosamprenavir. Risk C: Monitor
GuanFACINE: CYP3A4 Inhibitors (Moderate) may increase serum concentration of GuanFACINE. Management: Reduce the extended-release guanfacine dose 50% when combined with a moderate CYP3A4 inhibitor. Monitor for increased guanfacine toxicities when these agents are combined. Risk D: Consider Therapy Modification
Halofantrine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Halofantrine. Risk C: Monitor
Histamine H2 Receptor Antagonists: May decrease serum concentration of Fosamprenavir. Cimetidine may also inhibit the metabolism of the active metabolite amprenavir, making its effects on fosamprenavir/amprenavir concentrations difficult to predict. Risk C: Monitor
Hormonal Contraceptives: Protease Inhibitors may decrease serum concentration of Hormonal Contraceptives. Specifically, protease inhibitors may decrease concentrations of estrogens. Protease Inhibitors may increase serum concentration of Hormonal Contraceptives. Specifically, protease inhibitors may increase concentrations of progestins. Management: Use alternative or additional nonhormonal forms of contraception when estrogen-containing hormonal contraceptives are combined with protease inhibitors. Progestin-only contraceptives can be used without back up, but monitor for progestin toxicities. Risk D: Consider Therapy Modification
HYDROcodone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of HYDROcodone. Risk C: Monitor
Ibrutinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ibrutinib. Management: When treating B-cell malignancies, decrease ibrutinib to 280 mg daily when combined with moderate CYP3A4 inhibitors. When treating graft versus host disease, monitor patients closely and reduce the ibrutinib dose as needed based on adverse reactions. Risk D: Consider Therapy Modification
Ifosfamide: CYP3A4 Inhibitors (Moderate) may increase adverse/toxic effects of Ifosfamide. CYP3A4 Inhibitors (Moderate) may decrease active metabolite exposure of Ifosfamide. Risk C: Monitor
Iloperidone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Iloperidone. Risk C: Monitor
Indinavir: May increase active metabolite exposure of Fosamprenavir. Management: Consider alternatives to this combination. Safe and effective doses of fosamprenavir and indinavir during coadministration have not been established. Risk D: Consider Therapy Modification
Irinotecan Products: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Irinotecan Products. CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of Irinotecan Products. Specifically, the serum concentration of SN-38 may be increased. Risk C: Monitor
Isavuconazonium Sulfate: CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of Isavuconazonium Sulfate. Specifically, CYP3A4 Inhibitors (Moderate) may increase isavuconazole serum concentrations. Risk C: Monitor
Isradipine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Isradipine. Risk C: Monitor
Itraconazole: Fosamprenavir may increase serum concentration of Itraconazole. Itraconazole may increase active metabolite exposure of Fosamprenavir. Specifically, amprenavir concentrations may be increased. Management: Limit the adult maximum itraconazole dose to 200 mg/day with fosamprenavir/ritonavir. In patients receiving fosamprenavir without ritonavir, patients receiving greater than 400 mg/day itraconazole may also require dose reduction. Risk D: Consider Therapy Modification
Ivabradine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ivabradine. Risk X: Avoid
Ivacaftor: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ivacaftor. Management: Ivacaftor dose reductions may be required; consult full drug interaction monograph content for age- and weight-specific dosage recommendations. Risk D: Consider Therapy Modification
Ivosidenib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ivosidenib. Management: Avoid use of moderate CYP3A4 inhibitors with ivosidenib whenever possible. If combined, monitor for increased ivosidenib toxicities, including QTc prolongation. Risk D: Consider Therapy Modification
Ixabepilone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ixabepilone. Risk C: Monitor
Ketoconazole (Systemic): Fosamprenavir may increase serum concentration of Ketoconazole (Systemic). Ketoconazole (Systemic) may increase active metabolite exposure of Fosamprenavir. Specifically, amprenavir concentrations may be increased. Management: Limit the adult maximum ketoconazole dose to 200 mg/day with fosamprenavir/ritonavir. In patients receiving fosamprenavir without ritonavir, patients receiving greater than 400 mg/day ketoconazole may also require dose reduction. Risk D: Consider Therapy Modification
Lapatinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Lapatinib. Risk C: Monitor
Larotrectinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Larotrectinib. Risk C: Monitor
Lefamulin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Lefamulin. Management: Monitor for lefamulin adverse effects during coadministration of lefamulin tablets with moderate CYP3A4 inhibitors. Risk C: Monitor
Lemborexant: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Lemborexant. Risk X: Avoid
Leniolisib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Leniolisib. Risk C: Monitor
Lercanidipine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Lercanidipine. Risk C: Monitor
Levamlodipine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Levamlodipine. Risk C: Monitor
Levoketoconazole: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Levoketoconazole. Risk C: Monitor
Levomethadone: Fosamprenavir may decrease serum concentration of Levomethadone. Risk C: Monitor
Levomilnacipran: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Levomilnacipran. Risk C: Monitor
Lidocaine (Systemic): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Lidocaine (Systemic). CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of Lidocaine (Systemic). Specifically, concentrations of monoethylglycinexylidide (MEGX) may be increased. Risk C: Monitor
Lomitapide: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Lomitapide. Risk X: Avoid
Lonafarnib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Lonafarnib. Risk C: Monitor
Lopinavir: Fosamprenavir may decrease serum concentration of Lopinavir. Specifically, amprenavir (the active metabolite of fosamprenavir) may decrease the serum concentration of lopinavir. Lopinavir may decrease serum concentration of Fosamprenavir. Specifically, lopinavir/ritonavir may decrease the serum concentration of amprenavir (the active metabolite of fosamprenavir) Risk X: Avoid
Lovastatin: Fosamprenavir may increase serum concentration of Lovastatin. Risk X: Avoid
Lovotibeglogene Autotemcel: Antiretroviral Agents may decrease therapeutic effects of Lovotibeglogene Autotemcel. Risk X: Avoid
Lumateperone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Lumateperone. Management: Limit the lumateperone dose to 21 mg once daily when used with a moderate CYP3A4 inhibitor. Risk D: Consider Therapy Modification
Lurasidone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Lurasidone. Management: Reduce the lurasidone dose by half when initiating therapy with a moderate CYP3A4 inhibitor. If initiating lurasidone in a patient already receiving a moderate CYP3A4 inhibitor, start lurasidone at 20 mg/day with a max dose of 80 mg/day. Risk D: Consider Therapy Modification
Lurbinectedin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Lurbinectedin. Management: Avoid concomitant use of lurbinectedin and moderate CYP3A4 inhibitors when possible. If combined, reduce the lurbinectedin dose by 50%. Risk D: Consider Therapy Modification
Macitentan: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Macitentan. Risk C: Monitor
Manidipine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Manidipine. Risk C: Monitor
Maraviroc: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Maraviroc. Risk C: Monitor
Mavacamten: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Mavacamten. Management: Start mavacamten at 5 mg/day if stable on a moderate CYP3A4 inhibitor, and reduce the mavacamten dose by one dose level if initiating a moderate CYP3A4 inhibitor. Avoid initiating moderate CYP3A4 inhibitors in patients on mavacamten 2.5 mg/day. Risk D: Consider Therapy Modification
Mavorixafor: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Mavorixafor. Risk C: Monitor
Meperidine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Meperidine. Risk C: Monitor
Methadone: Fosamprenavir may decrease serum concentration of Methadone. Risk C: Monitor
MethylPREDNISolone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of MethylPREDNISolone. Risk C: Monitor
Methysergide: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Methysergide. Risk X: Avoid
Midazolam: Protease Inhibitors may increase serum concentration of Midazolam. Management: Oral midazolam is contraindicated with protease inhibitors. Avoid use with nasal midazolam. Consider alternatives to use with other routes of midazolam (IV, IM) when possible. Consider use of lower midazolam doses if combined. Risk X: Avoid
Midostaurin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Midostaurin. Risk C: Monitor
MiFEPRIStone: Fosamprenavir may increase serum concentration of MiFEPRIStone. Management: For treatment of hyperglycemia in Cushing's syndrome, start mifepristone at 300 mg/day, may titrate to a maximum of 900 mg/day. If starting fosamprenavir and taking > 300 mg/day mifepristone, decrease the mifepristone dose by 300 mg/day. Risk D: Consider Therapy Modification
Mirodenafil: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Mirodenafil. Risk C: Monitor
Mitapivat: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Mitapivat. Management: When coadministered with moderate CYP3A4 inhibitors, doses of mitapivat should not exceed 20 mg twice daily. Additionally, patients should be monitored for changes in hemoglobin response and increased mitapivat adverse effects. Risk D: Consider Therapy Modification
Mobocertinib: CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of Mobocertinib. CYP3A4 Inhibitors (Moderate) may increase serum concentration of Mobocertinib. Management: Avoid use of moderate CYP3A4 inhibitors with mobocertinib when possible. If combined, the mobocertinib dose should be reduced by approximately 50% (ie, from 160 mg to 80 mg, 120 mg to 40 mg, or 80 mg to 40 mg). Monitor QTc interval closely. Risk D: Consider Therapy Modification
Naldemedine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Naldemedine. Risk C: Monitor
Nalfurafine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Nalfurafine. Risk C: Monitor
Naloxegol: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Naloxegol. Management: The use of naloxegol and moderate CYP3A4 inhibitors should be avoided. If concurrent use is unavoidable, reduce naloxegol dose to 12.5 mg once daily and monitor for signs of opiate withdrawal (eg, hyperhidrosis, chills, diarrhea, anxiety, irritability). Risk D: Consider Therapy Modification
Nelfinavir: May increase active metabolite exposure of Fosamprenavir. Management: Consider alternatives to this combination. Safe and effective doses of fosamprenavir and nelfinavir during coadministration have not been established. Risk D: Consider Therapy Modification
Neratinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Neratinib. Risk C: Monitor
Nevirapine: May decrease active metabolite exposure of Fosamprenavir. Fosamprenavir may increase serum concentration of Nevirapine. Management: Coadministration of nevirapine and fosamprenavir is not recommended without concurrent ritonavir. However, when nevirapine and fosamprenavir/ritonavir (twice daily) are used in combination, no dose adjustment is required. Risk D: Consider Therapy Modification
NIFEdipine (Topical): CYP3A4 Inhibitors (Moderate) may increase serum concentration of NIFEdipine (Topical). Risk C: Monitor
NIFEdipine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of NIFEdipine. Risk C: Monitor
NiMODipine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of NiMODipine. Risk C: Monitor
Nirogacestat: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Nirogacestat. Risk X: Avoid
Nisoldipine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Nisoldipine. Risk X: Avoid
Nitrendipine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Nitrendipine. Risk C: Monitor
Olaparib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Olaparib. Management: Avoid use of moderate CYP3A4 inhibitors with olaparib, if possible. If such concurrent use cannot be avoided, the dose of olaparib tablets should be reduced to 150 mg twice daily and the dose of olaparib capsules should be reduced to 200 mg twice daily. Risk D: Consider Therapy Modification
Oliceridine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Oliceridine. Risk C: Monitor
Olmutinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Olmutinib. Risk C: Monitor
Omaveloxolone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Omaveloxolone. Management: Avoid this combination if possible. If coadministration is required, decrease the omaveloxolone dose to 100 mg daily and monitor closely for adverse reactions. If adverse reactions occur, decrease omaveloxolone to 50 mg daily. Risk D: Consider Therapy Modification
Ombitasvir, Paritaprevir, Ritonavir, and Dasabuvir: May increase active metabolite exposure of Fosamprenavir. Fosamprenavir may increase serum concentration of Ombitasvir, Paritaprevir, Ritonavir, and Dasabuvir. Management: Use of ritonavir-boosted fosamprenavir with ombitasvir/paritaprevir/ritonavir/dasabuvir is not recommended. Consider a reduced dose of fosamprenavir 1400 mg once daily (unboosted) when used with ombitasvir/paritaprevir/ritonavir/dasabuvir. Risk D: Consider Therapy Modification
Orlistat: May decrease serum concentration of Antiretroviral Agents. Risk C: Monitor
OxyCODONE: CYP3A4 Inhibitors (Moderate) may increase serum concentration of OxyCODONE. Serum concentrations of the active metabolite Oxymorphone may also be increased. Risk C: Monitor
PACLitaxel (Conventional): CYP3A4 Inhibitors (Moderate) may increase serum concentration of PACLitaxel (Conventional). Risk C: Monitor
PACLitaxel (Protein Bound): CYP3A4 Inhibitors (Moderate) may increase serum concentration of PACLitaxel (Protein Bound). Risk C: Monitor
Pacritinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Pacritinib. Risk C: Monitor
Palbociclib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Palbociclib. Risk C: Monitor
Palovarotene: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Palovarotene. Management: Avoid concomitant use of palovarotene and moderate CYP3A4 inhibitors when possible. If combined, decrease palovarotene dose by 50% as described in the full interaction monograph. Monitor for palovarotene toxicities when combined. Risk D: Consider Therapy Modification
Panobinostat: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Panobinostat. Risk C: Monitor
PARoxetine: Fosamprenavir may decrease serum concentration of PARoxetine. The active metabolite amprenavir is likely responsible for this effect. Risk C: Monitor
PAZOPanib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of PAZOPanib. Risk C: Monitor
Pemigatinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Pemigatinib. Management: If combined use cannot be avoided, reduce the pemigatinib dose from 13.5 mg daily to 9 mg daily, or from 9 mg daily to 4.5 mg daily. Resume prior pemigatinib dose after stopping the moderate inhibitor once 3 half-lives of the inhibitor has passed. Risk D: Consider Therapy Modification
Pexidartinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Pexidartinib. Management: If combined use cannot be avoided, pexidartinib dose should be reduced as follows: reduce pexidartinib doses of 500 mg or 375 mg daily to 125 mg twice daily; reduce pexidartinib 250 mg daily to 125 mg once daily. Risk D: Consider Therapy Modification
Phenytoin: Fosamprenavir may decrease serum concentration of Phenytoin. Specifically, fosamprenavir boosted with ritonavir may decrease phenytoin concentrations. Phenytoin may decrease serum concentration of Fosamprenavir. Specifically, phenytoin may decrease the concentration of the active metabolite amprenavir. Risk C: Monitor
Pimavanserin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Pimavanserin. Risk C: Monitor
Pimecrolimus: CYP3A4 Inhibitors (Moderate) may decrease metabolism of Pimecrolimus. Risk C: Monitor
Pimozide: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Pimozide. Risk X: Avoid
Piperaquine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Piperaquine. Risk C: Monitor
Pirtobrutinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Pirtobrutinib. Risk C: Monitor
PONATinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of PONATinib. Risk C: Monitor
Posaconazole: Fosamprenavir may decrease serum concentration of Posaconazole. Posaconazole may decrease active metabolite exposure of Fosamprenavir. Risk C: Monitor
Pralsetinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Pralsetinib. Management: If this combo cannot be avoided, decrease pralsetinib dose from 400 mg daily to 300 mg daily; from 300 mg daily to 200 mg daily; and from 200 mg daily to 100 mg daily. Risk D: Consider Therapy Modification
Prazepam: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Prazepam. Risk C: Monitor
Praziquantel: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Praziquantel. Risk C: Monitor
Propafenone: Fosamprenavir may increase serum concentration of Propafenone. Management: Concurrent use of ritonavir-boosted fosamprenavir with propafenone is contraindicated. The use of non-ritonavir-boosted fosamprenavir with propafenone is not specifically contraindicated but should only be undertaken with caution. Risk X: Avoid
QUEtiapine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of QUEtiapine. Risk C: Monitor
Quinidine (Non-Therapeutic): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Quinidine (Non-Therapeutic). Risk C: Monitor
QuiNIDine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of QuiNIDine. Risk C: Monitor
QuiNINE: CYP3A4 Inhibitors (Moderate) may increase serum concentration of QuiNINE. Risk C: Monitor
Raltegravir: Fosamprenavir may decrease serum concentration of Raltegravir. Raltegravir may decrease serum concentration of Fosamprenavir. Risk X: Avoid
Ranolazine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ranolazine. Management: Limit the ranolazine dose to a maximum of 500 mg twice daily in patients concurrently receiving moderate CYP3A4 inhibitors. Monitor for increased ranolazine effects and toxicities during concomitant use. Risk D: Consider Therapy Modification
Red Yeast Rice: Fosamprenavir may increase serum concentration of Red Yeast Rice. Risk X: Avoid
Regorafenib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Regorafenib. CYP3A4 Inhibitors (Moderate) may decrease active metabolite exposure of Regorafenib. Risk C: Monitor
Repotrectinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Repotrectinib. Risk X: Avoid
Ribociclib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ribociclib. Risk C: Monitor
Rifabutin: May increase serum concentration of Fosamprenavir. Fosamprenavir may increase active metabolite exposure of Rifabutin. Fosamprenavir may increase serum concentration of Rifabutin. Management: Reduce rifabutin doses during fosamprenavir coadministration, by at least 50% when used with fosamprenavir alone or 75% (to a dose of 150 mg every other day or 3 times per week) when used with fosamprenavir/ritonavir. Risk D: Consider Therapy Modification
RifAMPin: May decrease serum concentration of Fosamprenavir. Specifically, concentrations of amprenavir (active metabolite) may be decreased. Risk X: Avoid
Rimegepant: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Rimegepant. Management: If taking rimegepant for the acute treatment of migraine, avoid a second dose of rimegepant within 48 hours when used concomitantly with moderate CYP3A4 inhibitors. No dose adjustment needed if using rimegepant for prevention of episodic migraine. Risk D: Consider Therapy Modification
Rivaroxaban: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Rivaroxaban. This warning is more specifically for drugs that are inhibitors of both CYP3A4 and P-glycoprotein. For erythromycin, refer to more specific erythromycin-rivaroxaban monograph recommendations. Risk C: Monitor
Roflumilast-Containing Products: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Roflumilast-Containing Products. Risk C: Monitor
Rosuvastatin: Protease Inhibitors may increase serum concentration of Rosuvastatin. Risk C: Monitor
Rupatadine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Rupatadine. Risk C: Monitor
Ruxolitinib (Systemic): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ruxolitinib (Systemic). Risk C: Monitor
Salmeterol: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Salmeterol. Risk C: Monitor
Saquinavir: May decrease active metabolite exposure of Fosamprenavir. Management: Consider alternatives to this combination. Safe and effective doses of fosamprenavir and saquinavir during coadministration have not been established. Risk X: Avoid
SAXagliptin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of SAXagliptin. Risk C: Monitor
Selpercatinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Selpercatinib. Management: Avoid combination if possible. If use is necessary, reduce selpercatinib dose as follows: from 120 mg twice/day to 80 mg twice/day, or from 160 mg twice/day to 120 mg twice/day. Risk D: Consider Therapy Modification
Selumetinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Selumetinib. Management: Avoid concomitant use when possible. If combined, selumetinib dose reductions are recommended and vary based on body surface area and selumetinib dose. For details, see the full drug interaction monograph or selumetinib prescribing information. Risk D: Consider Therapy Modification
Sertindole: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Sertindole. Risk X: Avoid
Sildenafil: Protease Inhibitors may increase serum concentration of Sildenafil. Management: Use of protease inhibitors and sildenafil for the treatment of PAH is contraindicated. If using sildenafil for the treatment of erectile dysfunction, limit the sildenafil dose to 25 mg and do not use more frequently than every 48 hours. Risk D: Consider Therapy Modification
Silodosin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Silodosin. Risk C: Monitor
Simeprevir: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Simeprevir. Risk X: Avoid
Simvastatin: Fosamprenavir may increase serum concentration of Simvastatin. Risk X: Avoid
Sirolimus (Conventional): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Sirolimus (Conventional). Management: Monitor for increased serum concentrations of sirolimus if combined with a moderate CYP3A4 inhibitor. Lower initial sirolimus doses or sirolimus dose reductions will likely be required. Risk D: Consider Therapy Modification
Sirolimus (Protein Bound): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Sirolimus (Protein Bound). Management: Reduce the dose of protein bound sirolimus to 56 mg/m2 when used concomitantly with a moderate CYP3A4 inhibitor. Risk D: Consider Therapy Modification
Solifenacin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Solifenacin. Risk C: Monitor
Sonidegib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Sonidegib. Management: Avoid concomitant use of sonidegib and moderate CYP3A4 inhibitors when possible. When concomitant use cannot be avoided, limit CYP3A4 inhibitor use to less than 14 days and monitor for sonidegib toxicity (particularly musculoskeletal adverse reactions). Risk D: Consider Therapy Modification
Sparsentan: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Sparsentan. Risk C: Monitor
St John's Wort: May decrease serum concentration of Fosamprenavir. Risk X: Avoid
SUFentanil: CYP3A4 Inhibitors (Moderate) may increase serum concentration of SUFentanil. Risk C: Monitor
SUNItinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of SUNItinib. Risk C: Monitor
Suvorexant: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Suvorexant. Management: The recommended dose of suvorexant is 5 mg daily in patients receiving a moderate CYP3A4 inhibitor. The dose can be increased to 10 mg daily (maximum dose) if necessary for efficacy. Risk D: Consider Therapy Modification
Suzetrigine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Suzetrigine. Management: Reduce suzetrigine dose as follows: initiate with 100 mg for 1 dose; then 12 hours after first dose, give 50 mg every 12 hours for doses 2, 3, and 4; then 50 mg every 24 hours for dose 5 and thereafter. Risk D: Consider Therapy Modification
Tacrolimus (Systemic): Protease Inhibitors may increase nephrotoxic effects of Tacrolimus (Systemic). Protease Inhibitors may decrease metabolism of Tacrolimus (Systemic). Management: Consider reducing the tacrolimus dose to 1 mg once or twice per week if coadministered with protease inhibitors that are strong inhibitors of CYP3A4. Monitor response, plasma concentrations (as appropriate), and for signs of toxicity. Risk D: Consider Therapy Modification
Tacrolimus (Topical): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Tacrolimus (Topical). Risk C: Monitor
Tadalafil: Fosamprenavir may increase serum concentration of Tadalafil. Management: Initiate tadalafil for pulmonary arterial hypertension at 20 mg after at least 1 week of fosamprenavir therapy. Increase to tadalafil 40 mg as tolerated. For erectile dysfunction, limit the tadalafil dose to 10 mg every 72 hours. Risk D: Consider Therapy Modification
Tamsulosin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Tamsulosin. Risk C: Monitor
Tazemetostat: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Tazemetostat. Management: Avoid when possible. If combined, reduce tazemetostat dose from 800 mg twice daily to 400 mg twice daily, from 600 mg twice daily to 400 mg in AM and 200 mg in PM, or from 400 mg twice daily to 200 mg twice daily. Risk D: Consider Therapy Modification
Temsirolimus: CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of Temsirolimus. Specifically, concentrations of sirolimus may be increased. Risk C: Monitor
Tetrahydrocannabinol and Cannabidiol: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Tetrahydrocannabinol and Cannabidiol. Risk C: Monitor
Tetrahydrocannabinol: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Tetrahydrocannabinol. Risk C: Monitor
Tezacaftor and Ivacaftor: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Tezacaftor and Ivacaftor. Management: If combined with moderate CYP3A4 inhibitors, give tezacaftor/ivacaftor in the morning, every other day; give ivacaftor in the morning, every other day on alternate days. Tezacaftor/ivacaftor dose depends on age and weight; see full Lexi-Interact monograph Risk D: Consider Therapy Modification
Thiotepa: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Thiotepa. CYP3A4 Inhibitors (Moderate) may decrease active metabolite exposure of Thiotepa. Risk C: Monitor
Ticagrelor: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ticagrelor. CYP3A4 Inhibitors (Moderate) may decrease active metabolite exposure of Ticagrelor. Risk C: Monitor
Tilidine: CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of Tilidine. CYP3A4 Inhibitors (Moderate) may increase serum concentration of Tilidine. Risk C: Monitor
Tipranavir: May decrease serum concentration of Protease Inhibitors. Protease Inhibitors may increase serum concentration of Tipranavir. Risk X: Avoid
Tofacitinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Tofacitinib. Risk C: Monitor
Tolterodine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Tolterodine. Risk C: Monitor
Tolvaptan: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Tolvaptan. Management: Avoid this combination with Samsca brand of tolvaptan. Reduce dose for Jynarque brand: 90 mg AM and 30 mg PM, reduce to 45 mg AM and 15 mg PM; 60 mg AM and 30 mg PM, reduce to 30 mg AM and 15 mg PM; 45 mg AM and 15 mg PM, reduce to 15 mg AM and PM. Risk D: Consider Therapy Modification
Toremifene: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Toremifene. Risk C: Monitor
Trabectedin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Trabectedin. Risk C: Monitor
TraMADol: CYP3A4 Inhibitors (Moderate) may increase serum concentration of TraMADol. CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of TraMADol. Risk C: Monitor
TraZODone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of TraZODone. Risk C: Monitor
Tretinoin (Systemic): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Tretinoin (Systemic). Risk C: Monitor
Triamcinolone (Systemic): CYP3A4 Inhibitors (Moderate) may increase serum concentration of Triamcinolone (Systemic). Risk C: Monitor
Triazolam: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Triazolam. Management: Consider triazolam dose reduction in patients receiving concomitant moderate CYP3A4 inhibitors. Risk D: Consider Therapy Modification
Ubrogepant: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Ubrogepant. Management: Use an initial ubrogepant dose of 50 mg and avoid a second dose for 24 hours when used with moderate CYP3A4 inhibitors. Risk D: Consider Therapy Modification
Udenafil: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Udenafil. Risk C: Monitor
Valbenazine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Valbenazine. CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of Valbenazine. Risk C: Monitor
Valproic Acid and Derivatives: Protease Inhibitors may decrease serum concentration of Valproic Acid and Derivatives. Risk C: Monitor
Vamorolone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Vamorolone. Risk C: Monitor
Vanzacaftor, Tezacaftor, and Deutivacaftor: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Vanzacaftor, Tezacaftor, and Deutivacaftor. Management: Age- and weight-specific dose reductions of vanzacaftor, tezacaftor, and deutivacaftor are recommended. Please see full Interact monograph or labeling for details. Risk D: Consider Therapy Modification
Vardenafil: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Vardenafil. Management: Limit Levitra (vardenafil) dose to a single 5 mg dose within a 24-hour period if combined with moderate CYP3A4 inhibitors. Avoid concomitant use of Staxyn (vardenafil) and moderate CYP3A4 inhibitors. Combined use is contraindicated outside of the US. Risk D: Consider Therapy Modification
Vemurafenib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Vemurafenib. Risk C: Monitor
Venetoclax: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Venetoclax. Management: Reduce the venetoclax dose by at least 50% in patients requiring concomitant treatment with moderate CYP3A4 inhibitors. Resume the previous venetoclax dose 2 to 3 days after discontinuation of moderate CYP3A4 inhibitors. Risk D: Consider Therapy Modification
Verapamil: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Verapamil. Risk C: Monitor
Vilazodone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Vilazodone. Risk C: Monitor
VinBLAStine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of VinBLAStine. Risk C: Monitor
VinCRIStine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of VinCRIStine. Risk C: Monitor
Vindesine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Vindesine. Risk C: Monitor
Vinflunine: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Vinflunine. CYP3A4 Inhibitors (Moderate) may increase active metabolite exposure of Vinflunine. Risk C: Monitor
Voclosporin: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Voclosporin. Management: Decrease the voclosporin dose to 15.8 mg in the morning and 7.9 mg in the evening when combined with moderate CYP3A4 inhibitors. Risk D: Consider Therapy Modification
Vorapaxar: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Vorapaxar. Risk C: Monitor
Warfarin: Fosamprenavir may increase serum concentration of Warfarin. Risk C: Monitor
Zanubrutinib: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Zanubrutinib. Management: Decrease the zanubrutinib dose to 80 mg twice daily during coadministration with a moderate CYP3A4 inhibitor. Further dose adjustments may be required for zanubrutinib toxicities, refer to prescribing information for details. Risk D: Consider Therapy Modification
Zopiclone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Zopiclone. Risk C: Monitor
Zuranolone: CYP3A4 Inhibitors (Moderate) may increase serum concentration of Zuranolone. Risk C: Monitor
Fosamprenavir (unboosted or boosted with ritonavir) is not one of the recommended antiretroviral agents for use in patients with HIV infection who are trying to conceive.
Patients with HIV infection 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 fosamprenavir and specific contraceptive methods.
Maximum viral suppression sustained below the limits of detection prior to conception is recommended for all persons with HIV who are planning a pregnancy. Prior to pregnancy, select or make changes to a specific antiretroviral regimen as part of a shared decision-making process. In most cases, recommendations based on data obtained from cisgender women can be applied to transgender and gender diverse people assigned female sex at birth.
Health care providers caring for couples planning a pregnancy when one or both partners are diagnosed with HIV infection may contact the National Perinatal HIV Hotline (888-448-8765) for clinical consultation (HHS [perinatal] 2024).
Fosamprenavir crosses the human placenta.
Outcome data specific to fosamprenavir use in pregnancy are no longer being reviewed and updated in the Health and Human Services (HHS) perinatal guidelines. Fosamprenavir (unboosted or boosted with ritonavir) is not one of the recommended antiretroviral agents for use during pregnancy and patients who are pregnant should be changed to a preferred or alternative therapy.
Maternal antiretroviral therapy (ART) may be associated with adverse pregnancy outcomes including preterm birth, low birth weight, and small for GA infants. High viral loads are also associated with adverse outcomes, including preterm birth and pregnancy loss. Treatment improves the health of the pregnant patient and reduces the risk of perinatal transmission. Do not withhold appropriate maternal ART due to concerns for adverse neonatal outcomes. Closely monitor for pregnancy complications. Document in utero ART exposure in the long-term medical record of a child born without HIV; evaluate for potential metabolic dysfunction if significant organ system abnormalities of unknown etiology (particularly of the CNS or heart) develop. The risk of hepatic dysfunction and gestational diabetes may be increased in pregnant patients taking protease inhibitors. Consider performing the standard glucose screening test earlier in pregnancy in patients who initiated protease inhibitor therapy prior to conception.
ART is recommended for all pregnant people with HIV to maximize their health, maintain the viral load below the limit of an ultrasensitive assay detection, and reduce the risk of perinatal transmission. Start ART prior to conception or as soon as possible during pregnancy. During pregnancy, select or make changes to a specific antiretroviral regimen as part of a shared decision-making process. Patients on fully suppressive regimens prior to pregnancy generally may continue the same regimen considering known pregnancy outcomes and pharmacokinetic data. Monitor pregnant patients more frequently than nonpregnant patients. ART initiated during pregnancy can be modified after delivery. In most cases, recommendations based on data obtained from cisgender women can be applied to transgender and gender diverse people assigned female sex at birth.
Data collection to monitor pregnancy and infant outcomes following exposure to ART is ongoing. Enroll all patients exposed to antiretroviral medications as early in pregnancy as possible in the Antiretroviral Pregnancy Registry (1-800-258-4263).
Health care providers caring for pregnant patients with HIV infection and their infants may contact the National Perinatal HIV Hotline (1-888-448-8765) for clinical consultation (HHS [perinatal] 2024).
It is not known if fosamprenavir is present in breast milk.
Provide patient-centered evidence-based counseling for infant feeding options as early as possible in pregnancy.
• Using properly prepared formula or pasteurized banked donor milk eliminates the risk of postnatal HIV transmission via breastfeeding.
• Counsel patients on antiretroviral therapy (ART) who achieve and maintain a consistently undetectable plasma viral load during pregnancy and postnatally about feeding options, including breastfeeding, formula feeding, or banked donor milk. Maintaining maximum viral suppression decreases but does not eliminate the risk of HIV transmission via breast milk. Temporary discontinuation of breastfeeding and use of replacement feeding may be required if maternal viral load becomes detectable or if mastitis or bleeding nipples develop. Permanent discontinuation of breastfeeding is recommended if the maternal HIV RNA is ≥200 copies/mL.
• Formula feeding or banked donor milk is recommended for persons with HIV who are not on ART and/or do not have sustained viral suppression. Provide the infant presumptive antiretroviral therapy throughout breastfeeding and for up to 6 weeks after the last exposure to breast milk if the breastfeeding parent does not have sustained viral suppression but breastfeeding is continued; conduct infant virologic diagnostic testing at specified intervals.
• When the HIV status at delivery is not known, breast milk may be expressed and stored until a negative test is available.
• Discontinue breastfeeding immediately if HIV infection is diagnosed after breastfeeding has been initiated.
• Evaluate and provide support for maternal conditions that would make adherence to postpartum ART difficult.
Information is available for counseling and managing patients with HIV who are considering breastfeeding (1-888-448-8765). In most cases, recommendations based on data obtained from cisgender women can be applied to transgender and gender diverse people assigned female sex at birth (HHS [perinatal] 2024).
Adults should take oral suspension without food; however, pediatric patients should take oral suspension with food. Adult patients may take tablets without regard to food if not taken with ritonavir. Pediatric (HHS [pediatric] 2018) and adult patients should take tablets with food if taken with ritonavir.
Prior to initiation and periodically during therapy, monitor viral load, CD4 count, glucose; triglycerides and cholesterol; liver function tests (in patients with underlying hepatitis B or C)
Fosamprenavir is rapidly and almost completely converted to amprenavir by cellular phosphatases in vivo. Amprenavir binds to the site of HIV-1 protease activity and inhibits cleavage of viral Gag-Pol polyprotein precursors into individual functional proteins required for infectious HIV. This results in the formation of immature, noninfectious viral particles.
Absorption: 63%
Protein-binding: ~90% (to alpha1-acid glycoprotein); decreased in hepatic impairment
Metabolism: Fosamprenavir is rapidly and almost completely converted to amprenavir by cellular phosphatases in gut epithelium; amprenavir is hepatically metabolized via CYP isoenzymes (primarily CYP3A4); glucuronide conjugation of oxidized metabolites also occurs
Bioavailability: Not established; food does not have a significant effect on absorption of tablets. Administration of oral suspension with food reduced maximal drug concentration (Cmax) by 46% and area under the curve (AUC) by 28%.
Half-life elimination: ~7.7 hours (amprenavir)
Time to peak, plasma: 1.5 to 4 hours (median: 2.5 hours)
Excretion: Minimal excretion of unchanged drug in urine (1%) and feces; 75% of dose excreted as metabolites via biliary tract into feces and 14% excreted as metabolites in urine
Hepatic function impairment: AUC of amprenavir was increased by ~22% in mild hepatic impairment, by ~70% in moderate hepatic impairment, and by ~80% in severe hepatic impairment. Protein binding also decreased.
Pediatric: For children 2 to 18 years of age, the AUC is 31.4 to 93.4 mcg•h/mL, Cmax is 5 to 6.07 mcg/mL, and Cmin is 0.454 to 2.69 mcg/mL.
