Therapeutic reservoir effect
The observation that topical allylamines exhibit a tendency to produce greater sustained cure outcomes after treatment of CDIs appears to relate at least partially to persistence of a cutaneous therapeutic reservoir of the drug after its application is stopped.26 Figure 6 outlines the objectives and methodology of a tape-stripping study that evaluated the detection and relevance of naftifine levels in the SC up to 4 weeks after the last application of naftifine 2% cream.42 Table 1 depicts the results, including results with inner strips, which provide a better assessment of SC levels of naftifine that may correlate with therapeutic reservoir effect, with results suggesting that naftifine persists in the SC for several weeks after its application is stopped. With repeated application, the epidermal levels of naftifine remain relatively unchanged at the sites of application and persist for several weeks post-treatment, which is consistent with a bioavailable depot or reservoir of naftifine. The detection of naftifine in the SC up to 4 weeks post-treatment provides a possible explanation for the observed progressive improvements in efficacy rates during the treatment period and up to 4 weeks post-treatment in clinical trials using naftifine 2% cream.42
CONCLUSION
Superficial cutaneous fungal infections, especially CDIs, are commonly seen in clinical practice and can exhibit a variety of presentations. In many cases, a topical antifungal agent can effectively eradicate CDIs as long as an adequate duration of therapy is completed. Overall, the topical allylamine agents have been shown to provide faster onset and greater sustained clearance than imidazole agents for CDIs. Topical naftifine is an allylamine antifungal agent with a long track record of efficacy and safety.
