Onychomycosis: Limited data available (Ref): Children and Adolescents:
10 to 20 kg: Oral: 62.5 mg once daily for 6 weeks (fingernails) or 12 weeks (toenails).
>20 to 40 kg: Oral: 125 mg once daily for 6 weeks (fingernails) or 12 weeks (toenails).
>40 kg: Oral: 250 mg once daily for 6 weeks (fingernails) or 12 weeks (toenails).
Tinea capitis: Limited data available: Note: Preferred treatment agent varies based on causative pathogen (known or suspected). For infections caused by Trichophyton tonsurans (~95% of cases in the United States), terbinafine is considered superior to griseofulvin (Ref). For Microsporum spp. infections, griseofulvin is preferred over terbinafine. If terbinafine is used for Microsporum infections, higher-dose regimens are preferred (Ref).
Standard-dose regimen:
Children and Adolescents: Note: Dosing based on 4 to 6 mg/kg/day (Ref)
10 to <20 kg: Oral: 62.5 mg once daily.
20 to 40 kg: Oral: 125 mg once daily.
>40 kg: Oral: 250 mg once daily.
Higher-dose regimen (Ref):
Children and Adolescents:
10 to <25 kg: Oral: 125 mg once daily.
25 to 35 kg: Oral: 187.5 mg once daily.
>35 kg: Oral: 250 mg once daily.
Duration of therapy: Typically ~4 to 6 weeks but may vary based on pathogen and clinical response; Microsporum canis may require treatment for longer duration (eg, up to 12 weeks) (Ref).
Tinea corporis (ringworm), tinea cruris (jock itch), and tinea pedis (athlete's foot): Very limited data available: Note: Dosing is extrapolated from tinea capitis treatment studies; oral therapy should be reserved for disease that does not respond to topical therapy or for extensive/severe infection (Ref).
Children and Adolescents: Note: Dosing based on 4 to 6 mg/kg/day (Ref).
10 to <20 kg: Oral: 62.5 mg once daily (Ref).
20 to 40 kg: Oral: 125 mg once daily (Ref).
>40 kg: Oral: 250 mg once daily (Ref).
Duration of therapy: Typically ≥2 weeks (Ref).
There are no dosage adjustments provided in the manufacturer's labeling; however, clearance is decreased ~50% in adult patients with CrCl ≤50 mL/minute.
There are no pediatric-specific dosage adjustments provided in the manufacturer's labeling; use is contraindicated in adults with chronic or active hepatic disease.
(For additional information see "Terbinafine (systemic): Drug information")
Onychomycosis:
Continuous dosing: Oral: 250 mg once daily for 6 weeks (fingernail) or 12 weeks (toenail).
Pulsed dosing (alternative dosing method) (off label):
Note: Optimal dosing regimen not established. Pulsed dosing is less effective than continuous dosing (Ref).
Oral: 250 mg once daily for 4 weeks, off for 4 weeks, then resume with 250 mg once daily for 4 weeks (Ref) or 500 mg/day in 1 or 2 divided doses for 1 week repeated every 4 weeks for 3 months (Ref).
Tinea infection:
Dermatophyte folliculitis (tinea barbae, Majocchi granuloma) (off-label use): Oral: 250 mg once daily; duration is typically 2 to 6 weeks or until clinical resolution (Ref).
Tinea capitis (off-label use): Oral: 250 mg once daily for 4 to 6 weeks (Ref).
Tinea corporis/tinea cruris (alternative agent) (off-label use): Note: For disease that is extensive or refractory to topical therapy (Ref).
Oral: 250 mg once daily for 1 to 2 weeks (Ref).
Tinea pedis/tinea manuum (alternative agent) (off-label use): Note: For disease that is extensive or refractory to topical therapy (Ref).
Oral: 250 mg once daily for 2 weeks (Ref).
The renal dosing recommendations are based upon the best available evidence and clinical expertise. Senior Editorial Team: Bruce Mueller, PharmD, FCCP, FASN, FNKF; Jason A. Roberts, PhD, BPharm (Hons), B App Sc, FSHP, FISAC; Michael Heung, MD, MS.
Altered kidney function: Oral:
CrCl ≥50 mL/minute: No dosage adjustment necessary.
CrCl 20 to <50 mL/minute: Administer 50% of the usual dose (Ref).
CrCl <20 mL/minute: Use of alternative agent may be preferred (expert opinion); has not been adequately studied in this population. If necessary, administer 50% of usual dose and monitor frequently for adverse effects (eg, gastrointestinal, hepatic) (Ref).
Hemodialysis, intermittent (thrice weekly): Unlikely to be significantly dialyzed (highly protein bound, large Vd) (Ref):
Oral: Use of alternative agent may be preferred; has not been adequately studied in this population. If necessary, administer 50% of usual dose and monitor frequently for adverse effects (eg, gastrointestinal, hepatic) (Ref).
Peritoneal dialysis: Unlikely to be significantly dialyzed (highly protein bound, large Vd) (Ref):
Oral: Use of alternative agent may be preferred; has not been adequately studied in this population. If necessary, administer 50% of usual dose and monitor frequently for adverse effects (eg, gastrointestinal, hepatic) (Ref).
CRRT: Oral: Use of alternative agent may be preferred; has not been adequately studied in this population. If necessary, administer 50% of usual dose and monitor frequently for adverse effects (eg, gastrointestinal, hepatic) (Ref).
PIRRT (eg, sustained, low-efficiency diafiltration): Oral: Use of alternative agent may be preferred; has not been adequately studied in this population. If necessary, administer 50% of usual dose and monitor frequently for adverse effects (eg, gastrointestinal, hepatic) (Ref).
The liver dosing recommendations are based upon the best available evidence and clinical expertise. Senior Editorial Team: Matt Harris, PharmD, MHS, BCPS, FAST, FCCP; Jeong Park, PharmD, MS, BCPS, FCCP, FAST; Arun Jesudian, MD; Sasan Sakiani, MD.
Note : No long-term pharmacokinetic or safety data are available for use in patients with cirrhosis (Ref).
Liver impairment prior to treatment initiation:
Child-Turcotte-Pugh class A to C: Oral: Use is contraindicated (Ref).
Terbinafine may cause hepatotoxicity (ranging from mild and asymptomatic increased serum transaminases to hepatic failure) (Ref). Terbinafine liver injury may present as hepatocellular hepatitis or cholestatic hepatitis, with some cases progressing to vanishing bile duct syndrome (Ref). Most cases of hepatotoxicity are self-limited; although, persistent and severe hepatocellular injury cases have been reported, requiring discontinuation of therapy or in rare cases liver transplantation (Ref). Resolution may be delayed (eg, 3 to 6 months) following discontinuation of therapy (Ref). Acute hepatic failure due to terbinafine therapy is rare (Ref).
Mechanism: Non–dose-related; possible mechanisms include immunologic (part of a hypersensitivity reaction) or a metabolically mediated effect (formation of mono-GSH conjugate which binds to hepatobiliary proteins (Ref).
Onset: Varied; typically within the first 4 to 6 weeks of therapy (Ref).
Risk factors:
• HLA-A* 33:01 allele (Ref)
Severe cutaneous adverse reactions (SCARs), including Stevens Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) (Ref), drug reaction with eosinophilia and systemic symptoms (DRESS) (Ref) and acute generalized exanthematous pustulosis (AGEP) (Ref) have been reported. Other delayed cutaneous reactions include pityriasis rosea (Ref), lichenoid eruptions (Ref), symmetrical drug-related intertriginous and flexural erythema (SDRIFE) (Ref) and subacute cutaneous lupus erythematosus (SCLE) (Ref).
Mechanism: Non–dose-related; immunologic. Delayed hypersensitivity reactions including SCARs are T-cell-mediated (Ref).
Onset: Delayed hypersensitivity reactions: Varied; SCARs usually occur 1 to 8 weeks after initiation (Ref), although AGEP may have a more rapid onset within 2 days (Ross 2018); re-exposure usually results in symptoms within 1 to 4 days (Ref). SCLE generally occurs within 4 to 8 weeks after initiation (Ref).
Risk factors:
• Females (SCLE) (Ref)
• Cross-reactivity: Terbinafine, an allylamine antifungal, is structurally similar to naftifine; although, documented cross-reactivity has not been established. No cross-reactivity between terbinafine and naftifine was noted on patch tests (Ref).
Dysgeusia (including ageusia; bitter/sour > salty/sweet) (Ref) and altered sense of smell (including anosmia) may occur and severe cases resulting in decreased food intake, weight loss, anxiety, or depression have been reported. Resolution may be delayed (eg, several weeks to >1 year) following discontinuation of therapy or in some cases, disturbance may be permanent.
Mechanism: Not well known; possible mechanisms include receptor dysfunction through the inhibition of cytochrome P450-dependent enzyme or alteration of the cell structure or function of taste-related neurons through interference of the cholesterol biosynthesis pathway (Ref).
Onset: Delayed; mean onset of taste loss was 35 days (Ref).
Risk factors (taste disturbance):
• Age (>55 years) (Ref)
• History of taste loss (Ref)
• Low body mass index (<21 kg/m2) (Ref)
Thrombotic microangiopathy (TMA), including thrombotic thrombocytopenic purpura and hemolytic-uremic syndrome, have been reported rarely (some fatal). Recurrent anemia and thrombocytopenia may occur within 2 weeks after discontinuation (Ref).
Mechanism: Non–dose-related; immunologic (anti-ADAMTS-13 antibodies may be increased) (Ref).
Onset: Intermediate; in one case report, occurred within ~2 weeks after therapy initiation (Ref).
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
>10%: Nervous system: Headache (13%)
1% to 10%:
Dermatologic: Pruritus (3%), skin rash (6%), urticaria (1%)
Gastrointestinal: Diarrhea (6%), dysgeusia (3%; may be severe and result in weight loss) (table 1) , dyspepsia (4%)
Drug (Terbinafine [Systemic]) |
Placebo |
Number of Patients (Terbinafine [Systemic]) |
Number of Patients (Placebo) |
---|---|---|---|
3% |
0.7% |
465 |
137 |
Hepatic: Increased serum transaminases (3%) (table 2)
Drug (Terbinafine [Systemic]) |
Placebo |
Number of Patients (Terbinafine [Systemic]) |
Number of Patients (Placebo) |
---|---|---|---|
3% |
1% |
465 |
137 |
Postmarketing:
Cardiovascular: Vasculitis
Dermatologic: Acute generalized exanthematous pustulosis (Ref), alopecia (Ref), bullous dermatitis (Ref), cutaneous lupus erythematosus (Ref), erythema multiforme (Ref), exacerbation of psoriasis (Ref), exfoliative dermatitis (Ref), lichenoid eruption (Ref), pityriasis rosea (Ref), psoriasiform eruption (Ref), skin photosensitivity (Ref), Stevens-Johnson syndrome (Ref), toxic epidermal necrolysis (Ref)
Gastrointestinal: Ageusia (Ref), cholestasis (Ref), pancreatitis, vomiting
Hematologic & oncologic: Agranulocytosis (Ref), anemia (Ref), hemolytic-uremic syndrome, pancytopenia (Ref), severe neutropenia (Ref), thrombocytopenia (Ref), thrombotic microangiopathy (Ref), thrombotic thrombocytopenic purpura (Ref)
Hepatic: Cholestatic hepatitis (Ref), hepatic failure (Ref), hepatic impairment, hepatocellular hepatitis (Ref)
Hypersensitivity: Anaphylaxis, angioedema, drug reaction with eosinophilia and systemic symptoms (Ref), serum sickness-like reaction
Nervous system: Altered sense of smell (Ref), anosmia (Ref), anxiety, depression, fatigue, hypoesthesia, malaise, paresthesia, vertigo
Neuromuscular & skeletal: Arthralgia, exacerbation of systemic lupus erythematosus (Ref), increased creatine phosphokinase in blood specimen, myalgia, rhabdomyolysis (Ref), systemic lupus erythematosus (Ref)
Ophthalmic: Decreased visual acuity, visual field defect
Otic: Auditory impairment, tinnitus
Respiratory: Flu-like symptoms
Miscellaneous: Fever
Hypersensitivity to terbinafine or any component of the formulation; chronic or active hepatic disease
Concerns related to adverse effects:
• Allylamine antifungal hypersensitivity: Use caution in patients sensitive to allylamine antifungals (eg, naftifine, butenafine); cross-sensitivity to terbinafine may exist.
• Ocular effects: Although rare, changes in the ocular lens and retina have been reported; discontinuation of therapy may be required.
Disease-related concerns:
• Autoimmune disease (Lupus): Precipitation or exacerbation of cutaneous or systemic lupus erythematosus has been observed; discontinue if signs and/or symptoms develop.
• Hepatic impairment: Use is contraindicated in patients with active or chronic hepatic disease; clearance is reduced by ~50% in hepatic cirrhosis.
• Renal impairment: Use with caution in patients with renal dysfunction (CrCl ≤50 mL/minute); clearance is reduced by ~50%.
Other warnings/precautions:
• Appropriate use: Due to potential toxicity, confirmation of diagnostic testing of nail or skin specimens prior to treatment of onychomycosis or dermatomycosis is recommended.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet, Oral:
Generic: 250 mg
Yes
Tablets (Terbinafine HCl Oral)
250 mg (per each): $12.67 - $13.02
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
Tablet, Oral:
LamISIL: 250 mg [DSC]
Generic: 250 mg
25 mg/mL Oral Suspension:
A 25 mg/mL oral suspension may be made using tablets. Crush twenty 250 mg tablets and reduce to a fine powder. Add small amount of a 1:1 mixture of Ora-Sweet and Ora-Plus and mix to a uniform paste; mix while adding the vehicle in geometric proportions to almost 200 mL; transfer to a calibrated bottle, rinse mortar with vehicle, and add quantity of vehicle sufficient to make 200 mL. Label "shake well" and "refrigerate". Stable 42 days.
Oral: Tablets: Administer without regard to meals.
Oral: Administer without regard to meals.
Store below 25°C (77°F). Protect from light.
An FDA-approved patient medication guide, which is available with the product information and as follows, must be dispensed with this medication:
Lamisil: https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/020539s033lbl.pdf#page=11
Treatment of onychomycosis of the toenail or fingernail due to susceptible dermatophytes (FDA approved in adults); has also been used in the treatment of tinea capitis, tinea corporis, tinea cruris, and tinea pedis.
Terbinafine may be confused with terbutaline
LamISIL may be confused with LaMICtal, Lomotil
Substrate of CYP1A2 (Minor), CYP2C19 (Minor), CYP2C9 (Minor), CYP3A4 (Minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential; Inhibits CYP2D6 (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.
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
Ajmaline: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Ajmaline. Risk C: Monitor
Amitriptyline: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Amitriptyline. CYP2D6 Inhibitors (Moderate) may increase active metabolite exposure of Amitriptyline. Risk C: Monitor
Amoxapine: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Amoxapine. Risk C: Monitor
Amphetamines: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Amphetamines. Management: Monitor for amphetamine toxicities (including serotonin syndrome) if used with a moderate CYP2D6 inhibitor. Initiate amphetamine therapy at lower doses, monitor frequently, and adjust doses as needed. Discontinue amphetamines if serotoinin syndrome occurs Risk C: Monitor
ARIPiprazole Lauroxil: CYP2D6 Inhibitors (Moderate) may increase active metabolite exposure of ARIPiprazole Lauroxil. Risk C: Monitor
ARIPiprazole: CYP2D6 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
Atomoxetine: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Atomoxetine. Risk C: Monitor
Brexpiprazole: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Brexpiprazole. Management: If brexpiprazole is to be used together with both a moderate CYP2D6 inhibitor and a strong or moderate CYP3A4 inhibitor, the brexpiprazole dose should be reduced to 25% of the usual dose when treating indications other than major depressive disorder. Risk C: Monitor
Carvedilol: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Carvedilol. Risk C: Monitor
ClomiPRAMINE: CYP2D6 Inhibitors (Moderate) may increase serum concentration of ClomiPRAMINE. CYP2D6 Inhibitors (Moderate) may increase active metabolite exposure of ClomiPRAMINE. Risk C: Monitor
CloZAPine: CYP2D6 Inhibitors (Moderate) may increase serum concentration of CloZAPine. Risk C: Monitor
Codeine: CYP2D6 Inhibitors (Moderate) may decrease therapeutic effects of Codeine. These CYP2D6 inhibitors may prevent the metabolic conversion of codeine to its active metabolite morphine. Risk C: Monitor
CycloSPORINE (Systemic): Terbinafine (Systemic) may decrease serum concentration of CycloSPORINE (Systemic). Risk C: Monitor
Desipramine: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Desipramine. Risk C: Monitor
Deutetrabenazine: CYP2D6 Inhibitors (Moderate) may increase active metabolite exposure of Deutetrabenazine. Risk C: Monitor
Dextromethorphan: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Dextromethorphan. Risk C: Monitor
Doxepin (Systemic): CYP2D6 Inhibitors (Moderate) may increase serum concentration of Doxepin (Systemic). Risk C: Monitor
Doxepin (Topical): CYP2D6 Inhibitors (Moderate) may increase serum concentration of Doxepin (Topical). Risk C: Monitor
DOXOrubicin (Conventional): CYP2D6 Inhibitors (Moderate) may increase serum concentration of DOXOrubicin (Conventional). Risk X: Avoid
Eliglustat: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Eliglustat. Management: Eliglustat dose is 84 mg daily with CYP2D6 inhibitors. Use is contraindicated (COI) when also combined with strong CYP3A4 inhibitors. When also combined with a moderate CYP3A4 inhibitor, use is COI in CYP2D6 EMs or IMs and should be avoided in CYP2D6 PMs. Risk D: Consider Therapy Modification
Flecainide: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Flecainide. Risk C: Monitor
Haloperidol: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Haloperidol. Risk C: Monitor
Iboga: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Iboga. Risk C: Monitor
Iloperidone: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Iloperidone. CYP2D6 Inhibitors (Moderate) may decrease active metabolite exposure of Iloperidone. Specifically, concentrations of the metabolite P95 may be decreased. CYP2D6 Inhibitors (Moderate) may increase active metabolite exposure of Iloperidone. Specifically, concentrations of the metabolite P88 may be increased. Risk C: Monitor
Imipramine: CYP2D6 Inhibitors (Moderate) may increase active metabolite exposure of Imipramine. Concentrations of desipramine may be increased. CYP2D6 Inhibitors (Moderate) may increase serum concentration of Imipramine. Risk C: Monitor
Indoramin: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Indoramin. Risk C: Monitor
Lofepramine: CYP2D6 Inhibitors (Moderate) may increase active metabolite exposure of Lofepramine. The active metabolite of lofepramine is desipramine. Risk C: Monitor
Mequitazine: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Mequitazine. Risk X: Avoid
Methadone: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Methadone. Risk C: Monitor
Metoclopramide: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Metoclopramide. Risk C: Monitor
Metoprolol: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Metoprolol. Risk C: Monitor
Nebivolol: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Nebivolol. Risk C: Monitor
Nortriptyline: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Nortriptyline. Risk C: Monitor
Oliceridine: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Oliceridine. Risk C: Monitor
Olmutinib: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Olmutinib. Risk C: Monitor
PARoxetine: CYP2D6 Inhibitors (Moderate) may increase serum concentration of PARoxetine. Risk C: Monitor
Perhexiline: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Perhexiline. Risk C: Monitor
Perphenazine: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Perphenazine. Risk C: Monitor
Pimozide: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Pimozide. Risk C: Monitor
Pitolisant: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Pitolisant. Risk C: Monitor
Propafenone: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Propafenone. Risk C: Monitor
Propranolol: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Propranolol. Risk C: Monitor
Protriptyline: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Protriptyline. Risk C: Monitor
RifAMPin: May decrease serum concentration of Terbinafine (Systemic). Risk C: Monitor
RisperiDONE: CYP2D6 Inhibitors (Moderate) may increase serum concentration of RisperiDONE. Risk C: Monitor
Saccharomyces boulardii: Antifungal Agents (Systemic and Oral [Non-Absorbable]) may decrease therapeutic effects of Saccharomyces boulardii. Risk X: Avoid
Sertindole: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Sertindole. Risk C: Monitor
Sofpironium: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Sofpironium. Risk C: Monitor
Tamoxifen: CYP2D6 Inhibitors (Moderate) may decrease active metabolite exposure of Tamoxifen. Specifically, CYP2D6 inhibitors may decrease the metabolic formation of highly potent active metabolites. Management: Consider alternatives to the use of moderate CYP2D6 inhibitors with tamoxifen when possible, as the combination may be associated with reduced clinical effectiveness of tamoxifen. Risk D: Consider Therapy Modification
Tamsulosin: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Tamsulosin. Risk C: Monitor
Tetrabenazine: CYP2D6 Inhibitors (Moderate) may increase active metabolite exposure of Tetrabenazine. Specifically, concentrations of the active alpha- and beta-dihydrotetrabenazine metabolites may be increased. Risk C: Monitor
Thioridazine: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Thioridazine. Risk X: Avoid
Timolol (Systemic): CYP2D6 Inhibitors (Moderate) may increase serum concentration of Timolol (Systemic). Risk C: Monitor
TraMADol: CYP2D6 Inhibitors (Moderate) may increase serum concentration of TraMADol. CYP2D6 Inhibitors (Moderate) may decrease active metabolite exposure of TraMADol. Risk C: Monitor
Trimipramine: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Trimipramine. Risk C: Monitor
Valbenazine: CYP2D6 Inhibitors (Moderate) may increase active metabolite exposure of Valbenazine. Risk C: Monitor
Vortioxetine: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Vortioxetine. Risk C: Monitor
Zuclopenthixol: CYP2D6 Inhibitors (Moderate) may increase serum concentration of Zuclopenthixol. Risk C: Monitor
Published information related to the use of systemic terbinafine in pregnancy is limited (Gupta 1997a; Sarkar 2003).
Systemic therapy for the treatment of onychomycosis or tinea capitis is not recommended during pregnancy (Kaul 2017; Murase 2014).
AST/ALT prior to initiation, repeat if used >6 weeks; some experts have suggested that repeat testing at 6 weeks is unnecessary (Patel 2017); CBC (if used >6 weeks in immunocompromised patients).
Synthetic allylamine derivative that inhibits squalene epoxidase, a key enzyme in sterol biosynthesis in fungi. This results in a deficiency in ergosterol within the fungal cell membrane and results in fungal cell death.
Absorption: >70%.
Distribution: Distributed to sebum and skin predominantly.
Protein binding: Plasma: >99%.
Metabolism: Hepatic predominantly via CYP1A2, 3A4, 2C8, 2C9, and 2C19 to inactive metabolites.
Bioavailability: 40% (as a result of first-pass metabolism).
Half-life elimination: Terminal half-life: 200 to 400 hours; very slow release of drug from skin and adipose tissues occurs.
Effective half-life:
Children 5 to 11 years: 14.7 ± 4.3 hours (range: 9.8 to 25.7 hours) (Humbert 1998; Nejjam 1995).
Adults: ~36 hours.
Time to peak, plasma: Children and Adults: Within 2 hours (Abdel-Rahman 2005; manufacturer's labeling).
Excretion: Urine (80%, primarily as inactive metabolites); feces (20%) (Debruyne 2001).
Clearance:
Children 4 to 8 years: 1.41 ± 2.5 L/hour/kg (Abdel-Rahman 2005).
Adults: 0.47 ± 0.21 L/hour/kg (Abdel-Rahman 2005).
Altered kidney function: In CrCl ≤50 mL/minute, terbinafine clearance is decreased 50%.
Hepatic function impairment: Clearance is decreased 30% to 50% (Balfour 1992; Jensen 1989; manufacturer's labeling).