Tavaborole topical solution, 5%

SECTION 2: Hazards identification

Dose and Administration Apply tavaborole topical solution to affected toenails once daily for 48 weeks. Tavaborole topical solution should be applied to the entire toenail surface and under the tip of each toenail being treated. Tavaborole topical solution is for topical use only and not for oral, ophthalmic, or intravaginal use. Adverse effects Common adverse reactions occurring in ≥1% in subjects treated with tavaborole included application site exfoliation, ingrown toenail, application site erythema, and application site dermatitis. Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed 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. In two clinical trials, 791 subjects were treated with tavaborole topical solution. The most commonly reported adverse reactions are listed below; Post marketing Experience The following adverse reactions have been identified during post marketing use of tavaborole topical solution. Because these reactions 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 product exposure: Hypersensitivity; contact allergy. Over Dose Effect Overexposure may be irritating to the respiratory system. Pregnancy Comments Risk Summary There are no available data on tavaborole topical solution use in pregnant women to inform a drug associated risk for major birth defects, miscarriage or adverse maternal or fetal outcomes. In oral animal reproductive studies, administration of tavaborole during the period of organogenesis resulted in embryofetal toxicity and malformations at 570 times the Maximum Recommended Human Dose (MRHD) based on Area Under the Curve (AUC) comparisons in rats and embryofetal toxicity at 155 times the MRHD based on AUC comparisons in rabbits. Embryofetal toxicity was noted following dermal administration in rabbits up to 36 times the MRHD based on AUC comparisons. The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies carry some risk of birth defect, loss, or other adverse outcomes. The background risk of major birth defects in the U.S. general population is 2% to 4% and of miscarriage is 15% to 20% of clinically recognized pregnancies. Pharmacokinteics Tavaborole undergoes extensive metabolism. Renal excretion is the major route of elimination of the metabolites. In a clinical pharmacology trial of six healthy adult male volunteers who received a single topical application of 5% 14C-tavaborole solution, tavaborole conjugates and metabolites were shown to be excreted primarily in the urine. The pharmacokinetics (PK) of tavaborole was investigated in 24 adult subjects with distal subungual onychomycosis involving at least 4 toenails (including at least 1 great toenail) following a single dose and a 2-week daily topical application of 200 µL of a 5% solution of tavaborole to all ten toenails and 2 mm of skin surrounding each toenail. Steady state was achieved after 14 days of dosing. After a single dose, the mean (± standard deviation) peak concentration (Cmax) of tavaborole was 3.5 ± 2.3 ng/mL (n=21 with measurable concentrations, range 0.618 ng/mL to 10.2 ng/mL, LLOQ=0.5 ng/mL), and the mean AUClast ± SD was 44.4 ± 25.5 ng*hr/mL (n=21). After 2 weeks of daily dosing, the mean Cmax ± SD was 5.2 ± 3.5 ng/mL (n=24, range 1.5 ng/mL to 12.8 ng/mL), and the mean AUCτ ± SD was 75.8 ± 44.5 ng*hr/mL. In another study PK of tavaborole was investigated in 22 subjects aged 12 years to less than 17 years with distal subungual onychomycosis involving at least 4 toenails (including at least 1 great toenail with at least 20% involvement) following once daily application of 5% solution of tavaborole to all ten toenails and 2 mm of skin surrounding each toenail for 29 days. On Day 29, the mean ± SD Cmax was 5.9 ± 4.9 ng/mL (n=21 with measurable concentrations, range 1.0 ng/mL to 16.4 ng/mL, LLOQ=0.5 ng/mL), and the mean ± SD AUC0-24 was 76.0 ± 62.5 ng*hr/mL. Microbiology Mechanism of Action The mechanism of action of tavaborole is inhibition of fungal protein synthesis. Tavaborole inhibits protein synthesis by inhibition of an aminoacyl-transfer ribonucleic acid (tRNA) synthetase (AARS). Activity in vitro and in clinical infections Tavaborole has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections [see Indications and Usage (1)]: Trichophyton rubrum Trichophyton mentagrophytes Mechanism of Resistance Trichophyton mentagrophytes and Trichophyton rubrum strains from isolates collected in the clinical trials have not demonstrated resistance following repeated exposure to tavaborole. Strength 5 % Pack Size 10 mL NDC 72578-102-04 Revision No. 00