Intermittent versus continuous terbinafine in the treatment of toenail onychomycosis: a randomized, double-blind comparison.

BACKGROUND: Terbinafine is an established drug for the treatment of toenail onychomycosis. Minimizing the total dose of terbinafine and giving it intermittently could improve tolerability as well as compliance, provided efficacy is not compromised. OBJECTIVE: Two identical trials were conducted to compare the efficacy, safety and tolerability of the current standard regimen of terbinafine 250 mg daily with a new formulation of terbinafine given intermittently for three cycles of 2 weeks of treatment (350 mg daily) followed by 2 weeks off treatment. METHODS: A total of 2005 patients with a clinical diagnosis of subungual onychomycosis of the large toenail confirmed by microscopy and culture for a dermatophyte were recruited into the two trials and treated for 12 weeks. RESULTS: Patients with onychomycosis of prolonged duration (mean 9 years) and a median nail involvement of 63% with or without spikes, lateral involvement and white superficial onychomycosis (WSO) were included in the trial. The studies found a significant difference (p<0.05) in favour of standard daily dosing with terbinafine. Response rates for the primary variable complete cure (mycological and clinical cure) were lower with the new formulation in both Trial I (-5.8%; 95% CI -11.8, 0.07) and Trial II (difference -5.9%; 95% CI -12, 0.1). Both treatments were equally well tolerated, with approximately 11% of patients in both groups reporting at least one treatment-related adverse event. CONCLUSIONS: Pulsed dosing with terbinafine did not provide any clear safety advantages and was significantly less effective. Consequently, continuous treatment with terbinafine tablets remains the optimal therapy for onychomycosis.

An in-office diagnostic procedure to detect dermatophytes in a nationwide study of onychomycosis patients.

PURPOSE: To evaluate in-office dermatophyte test medium (DTM) culture as an alternative to traditional laboratory fungal culture for confirming a diagnosis of onychomycosis, and to determine the prevalence of dermatophytes as a cause of onychomycosis in patients not participating in a clinical trial. DESIGN: This nationwide multicenter prospective study enrolled 1100 adult patients with suspect onychomycosis. DTM and laboratory fungal culture results were compared for individual patients. METHODOLOGY: The 310 participating physicians obtained patient nail-bed specimens and divided them for testing by both diagnostic methods. The paired results of the two culture methods were compared using the kappa statistic. PRINCIPAL FINDINGS: Paired culture results were available for 975 of the 1100 enrolled patients. DTM results agreed with central laboratory cultures in 70 percent of cases. The kappa value of 0.40 indicated a moderate degree of correspondence between the two testing modalities. Overall, DTM culture indicated a dermatophyte in 616 patient specimens (56 percent) and central laboratory culture identified a dermatophyte in 528 of the specimens (48 percent). For the entire study population, dermatophytes were identified in 93 percent of the positive central laboratory cultures, confirming that dermatophytes caused the vast majority of the infections. The cost of each DTM culture was approximately $1, compared to $25 for each laboratory fungal culture. CONCLUSION: This study demonstrates that the in-office DTM culture for diagnosing onychomycosis has comparable utility to the traditional laboratory fungal culture, is less expensive, and yields faster results.