Terbinafine in the treatment of onychomycosis: a review of its efficacy in high-risk populations and in patients with nondermatophyte infections

Background: The prevalence of onychomycosis is higher in certain high-risk populations, such as the immunocompromised, diabetics and human immunodeficiency virus (HIV)-positive patients. These patients can also develop onychomycosis due to nondermatophyte fungi. Although the efficacy of terbinafine is well demonstrated in the treatment of conventional dermatophyte nail infection, there are few data on the efficacy of terbinafine in high-risk patient groups or in nondermatophyte fungi, which can be difficult to treat. Objectives: To review previously published data regarding the safety and efficacy of terbinafine in special patient populations, such as those with diabetes mellitus or HIV infection, those receiving immunosuppressive therapy, and patients with onychomycosis due to nondermatophyte fungi. Methods: A Medline literature search up to October 2002 was performed in order to identify relevant studies. Pertinent abstracts presented at international meetings were also included. Cure rates (per-protocol and intention-to-treat) were extracted or calculated. All available safety data were also collated. Results: Terbinafine was highly effective and well tolerated in patients with diabetes mellitus. Mycological cure rates of 62-78% were achieved in three studies, which is comparable with the efficacy in nondiabetic populations. Mycological cure rates of 64-91% were achieved in subsets of diabetic patients with Candida-positive nail cultures. The efficacy of terbinafine in patients receiving immunosuppressive therapy was also similar to that reported in immunocompetent patients. Levels of ciclosporin in the blood clearly decreased, with little clinical consequence; however, consideration should be given to the monitoring of ciclosporin levels in patients concomitantly receiving immunosuppressive therapy and terbinafine. Two small studies reported that terbinafine was also effective in treating onychomycosis in HIV-positive patients. Terbinafine was also effective and well tolerated in the treatment of nondermatophyte onychomycosis. Conclusions: This review suggests that terbinafine is a safe and effective treatment for onychomycosis in high-risk populations. However, the majority of these studies only included small numbers of patients and larger clinical trials are needed, especially in patients with HIV infection.