Naftifine

Risk Summary

There are no available data on naftifine gel use in pregnant women to evaluate a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes.

In animal reproduction studies, no adverse effects on embryofetal development were seen at oral doses administered during the period of organogenesis up to 37 times the maximum recommended human dose (MRHD) in pregnant rats or subcutaneous doses administered during the period of organogenesis up to 4 times the MRHD in pregnant rats or 7 times the MRHD in pregnant rabbits (see Data).

All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Data

Animal Data

Systemic embryofetal development studies were conducted in rats and rabbits. For the comparison of animal to human doses, the MRHD is set at 4 g 2% gel per day (1.33 mg/kg/day for a 60 kg individual).

Oral doses of 30, 100, and 300 mg/kg/day naftifine hydrochloride were administered during the period of organogenesis to pregnant female rats. No treatment-related effects on embryofetal toxicity were noted at doses up to 300 mg/kg/day (37 times the MRHD based on mg/m² comparison). Subcutaneous doses of 10 and 30 mg/kg/day naftifine hydrochloride were administered during the period of organogenesis to pregnant female rats. No treatment-related effects on embryofetal toxicity were noted at 30 mg/kg/day (4 times the MRHD based on mg/m² comparison). Subcutaneous doses of 3, 10, and 30 mg/kg/day naftifine hydrochloride were administered during the period of organogenesis to pregnant female rabbits. No treatment-related effects on embryofetal toxicity were noted at 30 mg/kg/day (7 times the MRHD based on mg/m² comparison).

A peri-and post-natal development study was conducted in rats. Oral doses of 30, 100, and 300 mg/kg/day naftifine hydrochloride were administered to female rats from gestational day 14 to lactation day 21. Reduced body weight gain of females during gestation and of the offspring during lactation was noted at 300 mg/kg/day (37 times the MRHD based on mg/m² comparison). No developmental toxicity was noted at 100 mg/kg/day (12 times the MRHD based on mg/m² comparison).

Risk Summary

There is no information available on the presence of naftifine hydrochloride in human milk, the effects of the drug on the breastfed infant, or the effects of the drug on milk production after topical application of naftifine gel to women who are breastfeeding. It is not known whether naftifine hydrochloride is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when naftifine hydrochloride is administered to a nursing woman.

The lack of clinical data during lactation precludes a clear determination of the risk naftifine gel to an infant during lactation. Therefore, the developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for naftifine gel and any potential adverse effects on the breastfed infant from naftifine gel or from the underlying maternal condition.

In a 2-year dermal carcinogenicity study, naftifine hydrochloride cream was administered to Sprague-Dawley rats at topical doses of 1%, 2% and 3% (10, 20, and 30 mg/kg/day naftifine hydrochloride). No drug-related tumors were noted in this study up to the highest dose evaluated in this study of 30 mg/kg/day (36 times the MRHD based on AUC comparison).

Naftifine hydrochloride revealed no evidence of mutagenic or clastogenic potential based on the results of two in vitro genotoxicity tests (Ames assay and Chinese hamster ovary cell chromosome aberration assay) and one in vivo genotoxicity test (mouse bone marrow micronucleus assay).

Oral administration of naftifine hydrochloride to rats, throughout mating, gestation, parturition, and lactation, demonstrated no effects on growth, fertility, or reproduction, at doses up to 100 mg/kg/day (12 times the MRHD based on mg/m² comparison).

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 clinical practice.

In two randomized, vehicle-controlled trials, 1143 subjects were treated with naftifine gel versus 571 subjects treated with the vehicle. The trial subjects were 12 to 92 years old, were primarily male (76%), and were 59% Caucasian, 38% Black or African American, and 23% Hispanic or Latino. Subjects received doses once daily, topically, for 2 weeks to cover the affected skin areas plus a ½-inch margin of surrounding healthy skin. The most common adverse reactions were application site reactions which occurred at the rate of 2% in naftifine gel arm versus 1% in vehicle arm. Most adverse reactions were mild in severity.

In an open-label pediatric pharmacokinetics and safety trial 22 pediatric subjects 12-17 years of age with interdigital tinea pedis received naftifine gel. The incidence of adverse reactions in the pediatric population was similar to that observed in adult population.

Cumulative irritancy testing revealed the potential for naftifine gel to cause irritation. There was no evidence that naftifine gel causes contact sensitization, phototoxicity, or photoallergenicity in healthy skin.

Postmarketing Experience

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 exposure. The following adverse reactions have been identified during post-approval use of naftifine hydrochloride: blisters, burning sensation, crusting, dryness, erythema/redness, inflammation, irritation, maceration, pain, pruritus [mild]/itching, rash and swelling.