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Thursday, June 02, 2011

Griseofulvin vs. Terbinafine for Tinea Capitis: Which Is Ahead?

Each agent has its uses in this common fungal infection in children.

Since the late 1950s, griseofulvin has been the treatment of choice for tinea capitis; it is very safe and inexpensive and is available in tablet or liquid forms. The main disadvantages are long treatment duration (6–8 weeks) and erratic absorption. Shorter treatment and longer tissue retention of drug have increased use of newer antifungal agents (terbinafine, itraconazole, and fluconazole) for adult fungal skin infections. These agents, however, are much more expensive, dosage forms are limited, and data regarding pediatric use are few.

Investigators performed a meta-analysis of randomized, controlled trials to compare griseofulvin with terbinafine for tinea capitis treatment in children and adults. Seven studies involving 2163 subjects were included, and clinical and mycological cure rates and adverse effects were compared. No significant differences in efficacy were found between griseofulvin (mean duration, 8 weeks; range, 6–12 weeks) and terbinafine (mean duration, 4 weeks; range, 2–6 weeks). Terbinafine was more efficacious for Trichophyton species and griseofulvin forMicrosporum species. Both agents had good safety profiles. The authors recommend that pretreatment and intermittent laboratory investigations are unnecessary in terbinafine treatment of healthy children because adverse side effects are rare, and the tests do not effectively predict these rare reactions.

Comment: Head-to-head studies of tinea capitis treatment in the U.S. are limited by FDA-required dosing of griseofulvin at 10 mg/kg/day, an outdated and inadequate dosage for Trichophyton tonsurans. Current U.S. practice for the microsize griseofulvin suspension is to use 20–25 mg/kg/day (the dose would need to be converted if ultramicrosize tablets are prescribed). In this meta-analysis of studies from around the world, griseofulvin dosing ranged from 6 to 20 mg/kg/day. Despite suboptimal dosing in many, griseofulvin beat terbinafine for Microsporum canis infections. Ideally, pretreatment fungal cultures can guide our choice of agent. Terbinafine works well against T. tonsuranswhen treatment duration is adequate, but terbinafine oral granules are prohibitively expensive; therefore, I prescribe tablets for children (cut in half, if needed). Itraconazole is another alternative to griseofulvin for M. canis infection in children. For T. tonsurans, I still prescribe a lot of griseofulvin: It's safe, it's cheap, and it works well when given correctly.

Mary Wu Chang, MD

Published in Journal Watch Dermatology May 20, 2011