TERBINAFINE- terbinafine_tablet

Terbinafine is an allylamine antifungal [see Clinical Pharmacology ( 12. 4 The pharmacodynamics of terbinafine tablets is unknown. Following oral administration, terbinafine is well absorbed (greater than 70%) and the bioavailability of terbinafine tablets as a result of first-pass metabolism is approximately 40%. Peak plasma concentrations of 1 mcg/mL appear within 2 hours after a single 250 mg dose; the AUC is approximately 4. An increase in the AUC of terbinafine of less than 20% is observed when terbinafine tablets are administered with food. In plasma, terbinafine is greater than 99% bound to plasma proteins and there are no specific binding sites. At steady-state, in comparison to a single dose, the peak concentration of terbinafine is 25% higher and plasma AUC increases by a factor of 2. 5; the increase in plasma AUC is consistent with an effective half-life of ~36 hours. Terbinafine is distributed to the sebum and skin. A terminal half-life of 200 to 400 hours may represent the slow elimination of terbinafine from tissues such as skin and adipose. Prior to excretion, terbinafine is extensively metabolized by at least seven CYP isoenzymes with major contributions from CYP2C9, CYP1A2, CYP3A4, CYP2C8, and CYP2C19. No metabolites have been identified that have antifungal activity similar to terbinafine. Approximately 70% of the administered dose is eliminated in the urine. In patients with renal impairment (creatinine clearance less than or equal to Terbinafine, an allylamine antifungal, inhibits biosynthesis of ergosterol, an essential component of fungal cell membrane, via inhibition of squalene epoxidase enzyme. This results in fungal cell death primarily due to the increased membrane permeability mediated by the accumulation of high concentrations of squalene but not due to ergosterol deficiency. Depending on the concentration of the drug and the fungal species test in vitro in vitro Terbinafine has been shown to be active against most strains of the following microorganisms both in vitro Trichophyton mentagrophytes Trichophyton rubrum The following in vitro In vitro Candida albicans Epidermophyton floccosum Scopulariopsis brevicaulis.

Terbinafine tablets, USP are indicated for the treatment of onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium). Prior to initiating treatment, appropriate nail specimens for laboratory testing [potassium hydroxide (KOH) preparation, fungal culture, or nail biopsy] should be obtained to confirm the diagnosis of onychomycosis. Terbinafine tablets are an allylamine antifungal indicated for the treatment of onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium).

Prior to administering, evaluate patients for evidence of chronic or active liver disease. 1 Fingernail onychomycosis: One 250 mg tablet, once daily for 6 weeks. 2 Toenail onychomycosis: One 250 mg tablet, once daily for 12 weeks. 2 Before administering terbinafine tablets, evaluate patients for evidence of chronic or active liver disease [see Contraindications (4) Warnings and Precautions (5. 1) Fingernail onychomycosis: One 250 mg tablet once daily for 6 weeks. Toenail onychomycosis: One 250 mg tablet once daily for 12 weeks. The optimal clinical effect is seen some months after mycological cure and cessation of treatment. This is related to the period required for outgrowth of healthy nail.

Common (greater than 2% of patients treated with terbinafine tablets) reported adverse events include headache, diarrhea, rash, dyspepsia, liver enzyme abnormalities, pruritus, taste disturbance, nausea, abdominal pain, and flatulence. 1 To report SUSPECTED ADVERSE REACTIONS, contact Cipla Ltd. at 1-866-604-3268 or FDA at 1-800-FDA-1088 or www. gov/medwatch. Because clinical trials are conducted under widely varying conditions, adverse reaction rates in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The most frequently reported adverse events observed in the three US/Canadian placebo-controlled trials are listed in the Table 1. The adverse events reported encompass gastrointestinal symptoms (including diarrhea, dyspepsia, and abdominal pain), liver test abnormalities, rashes, urticaria, pruritus, and taste disturbances. Changes in the ocular lens and retina have been reported following the use of terbinafine tablets in controlled trials. The clinical significance of these changes is unknown. In general, the adverse events were mild, transient, and did not lead to discontinuation from study participation. Most frequently reported adverse events observed in the 3 US/Canadian placebo-controlled trials *Liver enzyme abnormalities greater than or equal to 2x the upper limit of normal range. Image 1 The following adverse events have been identified during post-approval use of terbinafine tablets. Because these events are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Blood and lymphatic system disorders: Warnings and Precautions ( 5. 8 Immune system disorders: Warnings and Precautions ( 5. 7 Psychiatric disorders: Warnings and Precautions ( 5. 4 Nervous system disorders: Warnings and Precautions ( 5. 3 Eye disorders: Ear and labyrinth disorders: Vascular disorders: Gastrointestinal disorders: Hepatobiliary disorders: Warnings and Precautions ( 5. 1 Skin and subcutaneous tissue disorders: Warnings and Precautions 5. 6 Musculoskeletal and connective tissue disorders: General disorders and administration site conditions: Investigations:.

Terbinafine tablets are contraindicated in patients with: History of allergic reaction to oral terbinafine because of the risk of anaphylaxis [see Adverse Reactions (6. 2) Chronic or active liver disease [see Warnings and Precautions (5. 1) Chronic or active liver disease. ( 4 History of allergic reaction to oral terbinafine because of the risk of anaphylaxis.

Risk Summary Available data from postmarketing cases on the use of terbinafine tablets in pregnant women are insufficient to evaluate a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes. In animal reproduction studies, terbinafine did not cause malformations or any harm to the fetus when administered to pregnant rabbits and rats during the period of organogenesis at oral doses up to 12 and 23 times the maximum recommended human dose (MRHD) of 250 mg/day, respectively (see data) All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. The background risk of major birth defects and miscarriage for the indicated population is unknown; however, in the U. general population, the estimated background risk of major birth defects is 2%-4% and of miscarriage is 15%-20% of clinically recognized pregnancies. Data Animal Data In a rat peri-and postnatal development study, terbinafine doses of up to 300 mg/kg/day (12 times the MRHD based on BSA comparisons) given by oral gavage during late pregnancy and lactation (Day 15 of gestation to day 20 post-partum) had no adverse effects on parturition and lactation. Risk Summary After oral administration, terbinafine is present in human milk. However, there are no data on the effects on the breastfed child or on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for terbinafine tablets and any potential adverse effects on the breastfed child from terbinafine tablets or from the underlying maternal condition. The safety and efficacy of terbinafine tablets have not been established in pediatric patients with onychomycosis. Clinical studies of terbinafine tablets did not include sufficient numbers of subjects aged 65 years and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. In patients with renal impairment (creatinine clearance less than or equal to 50 mL/min), the use of terbinafine tablets has not been adequately studied. Terbinafine tablets are contraindicated for patients with chronic or active liver disease [see Contraindications (4) Warnings and Precautions (5.

Terbinafine is an inhibitor of CYP450 2D6 isozyme and has an effect on metabolism of desipramine. Drug interactions have also been noted with cimetidine, fluconazole, cyclosporine, rifampin, and caffeine. 1 In vivo max In vitro In vivo The influence of terbinafine on the pharmacokinetics of fluconazole, cotrimoxazole (trimethoprim and sulfamethoxazole), zidovudine or theophylline was not considered to be clinically significant. Coadministration of a single dose of fluconazole (100 mg) with a single dose of terbinafine resulted in a 52% and 69% increase in terbinafine C max max There have been spontaneous reports of increase or decrease in prothrombin times in patients concomitantly taking oral terbinafine and warfarin, however, a causal relationship between terbinafine tablets and these changes has not been established. Terbinafine clearance is increased 100% by rifampin, a CYP450 enzyme inducer, and decreased 33% by cimetidine, a CYP450 enzyme inhibitor. Terbinafine clearance is unaffected by cyclosporine. There is no information available from adequate drug-drug interaction studies with the following classes of drugs: oral contraceptives, hormone replacement therapies, hypoglycemics, phenytoins, thiazide diuretics, and calcium channel blockers. An evaluation of the effect of food on terbinafine tablets was conducted. An increase of less than 20% of the AUC of terbinafine was observed when terbinafine tablets were administered with food. Terbinafine tablets can be taken with or without food.

OVERDOSAGE
Clinical experience regarding overdose with oral terbinafine is limited. Doses up to 5 grams (20 times the therapeutic daily dose) have been taken without inducing serious adverse reactions. The symptoms of overdose included nausea, vomiting, abdominal pain, dizziness, rash, frequent urination, and headache.
NONCLINICAL TOXICOLOGY
In a 28-month oral carcinogenicity study in rats, an increase in the incidence of liver tumors was observed in males at the highest dose tested, 69 mg/kg/day (2 times the MRHD based on AUC comparisons of the parent terbinafine); however, even though dose-limiting toxicity was not achieved at the highest tested dose, higher doses were not tested. The results of a variety of in vitro E. typhimurium in vivo Oral reproduction studies in rats at doses up to 300 mg/kg/day (12 times the MRHD based on BSA comparisons) did not reveal any specific effects on fertility or other reproductive parameters. Intravaginal application of terbinafine hydrochloride at 150 mg/day in pregnant rabbits did not increase the incidence of abortions or premature deliveries nor affect fetal parameters. A wide range of in vivo in vitro ss.
CLINICAL STUDIES
The efficacy of terbinafine tablets in the treatment of onychomycosis is illustrated by the response of subjects with toenail and/or fingernail infections who participated in three US/Canadian placebo-controlled clinical trials. Results of the first toenail trial, as assessed at week 48 (12 weeks of treatment with 36 weeks follow-up after completion of therapy), demonstrated mycological cure, defined as simultaneous occurrence of negative KOH plus negative culture, in 70% of subjects. Fifty-nine percent (59%) of subjects experienced effective treatment (mycological cure plus 0% nail involvement or greater than 5mm of new unaffected nail growth); 38% of subjects demonstrated mycological cure plus clinical cure (0% nail involvement). In a second toenail trial of dermatophytic onychomycosis, in which nondermatophytes were also cultured, similar efficacy against the dermatophytes was demonstrated. The pathogenic role of the nondermatophytes cultured in the presence of dermatophytic onychomycosis has not been established. The clinical significance of this association is unknown. Results of the fingernail trial, as assessed at week 24 (6 weeks of treatment with 18 weeks follow-up after completion of therapy), demonstrated mycological cure in 79% of subjects, effective treatment in 75% of the subjects, and mycological cure plus clinical cure in 59% of the subjects. The mean time to overall success was approximately 10 months for the first toenail trial and 4 months for the fingernail trial. In the first toenail trial, for subjects evaluated at least 6 months after achieving clinical cure and at least 1 year after completing therapy with terbinafine tablets, the clinical relapse rate was approximately 15%.

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