Tuesday, May 27, 2014

What is the best topical antifungal for treating tinea pedis?

- Jennifer Middleton, MD, MPH

A section in this month's Prescriber's Letter regarding a new topical antifungal medication stated that a 2012 systematic review found no clinical difference among topical antifungals for treating dermatophyte infections. This statement contradicts what a clinical pharmacist once taught me: that topical terbinafine is superior to topical clotrimazole for treating tinea pedis. Given how frequently I treat tinea pedis, I have relied on this lesson countless times during my career to date. Thanks to the AFP By Topic on Skin Conditions I found an AFP article, "Dermatophyte Infections," citing the relevant randomized controlled trial (RCT) from 1993. Knowing from my Evidence-Based Medicine education that a well-done systematic review can trump a single RCT, I decided to check out both.

The 1993 study (that I assume my clinical pharmacist teacher referenced) was published in BMJ and divided 256 patients "with mycologically confirmed tinea pedis" into two groups; one group received 1% topical terbinafine twice daily for 1 week followed by 3 weeks of placebo, and the other group received 1% topical clotrimazole twice daily for 4 weeks.* The authors measured both microscopic and clinical cure rates, and terbinafine beat clotrimazole handily, with success rates of both measures combined of 89.7% vs 58.7% at week 4 and 89.7% vs 73.1% at week 6 (both p < 0.01).

The authors of the 2012 systematic review, published in the British Journal of Dermatology, looked at several comparisons among antifungal medications for multiple conditions. In one comparison, they reviewed 17 studies comparing allynes (medication class that includes terbinafine) and azoles (medication class that includes clotrimazole) for all topical dermatophyte infections and found no statistically significant difference.
The systematic review authors did not specifically single out studies comparing terbinafine and clotrimazole for tinea pedis, however.

For now, given that 1 week of therapy is probably preferable to most patients instead of 4, and given that the price difference between the two medications is negligible (around $10-16 for 30 grams of either), I will still favor terbinafine for treating tinea pedis. One option I will definitely not take is using the new brand new Luzu (luliconazole) referenced in this month's Prescriber's Letter for a reported $180 per 30 grams.

How do you choose which topical antifungal to prescribe for tinea pedis?

* According to Lexicomp, 1 week is a sufficient starting place for treating tinea pedis with terbinafine, but it recommends at least 4 weeks of clotrimazole.

No comments:

Post a Comment