Comparison of lindane and permethrin for scabies - adapted from the Archives of Dermatology 1996;132

Author: Barbara Apgar
Date: Nov 15, 1996

Lindane has been the primary therapy for scabies for more than 30 years. However, because of neurotoxic side effects attributed to this drug, alternative drugs such as 5 percent permethrin have been used, particularly in the pediatric population where the risk of toxic reaction is high. Permethrin is also used for the treatment of head lice. Because little clinically relevant literature is available to assess the absorption of permethrin, Franz and associates compared the percutaneous absorption of 1 percent lindane and 5 percent permethrin to evaluate the risk-benefit ratio of the two drugs.

A proposed overuse dose of lindane and permethrin was applied to human cadaver and guinea pig skin, and the skin was assessed at specific intervals over a 48-hour period. In vivo tests were used to measure the absorption, and results were quantified by gas chromatography.

Results indicated that absorption of the two drugs was nearly identical in guinea pig skin. However, in human skin, the results were significantly different. The rate of penetration rapidly rose within five hours after application of lindane, versus 10 to 20 hours after application of permethrin. Human skin was found to be 20-fold more permeable to lindane than to permethrin. When blood and brain levels of the drugs were measured in guinea pigs, a similar association was noted, represented by a four-fold greater concentration of lindane than permethrin.

Results indicate that lindane would provide a lesser margin of safety compared with permethrin. The authors cite three factors that favor permethrin over lindane for the topical treatment of scabies: lower inherent toxicity, lower percutaneous absorption and lower blood and brain levels. The latter two factors, when combined, indicate a 40-fold improvement in risk-benefit ratio for permethrin.

Franz TJ, et al. Comparative percutaneous absorption of lindane and permethrin. Arch Dermatol 1996;132:901-5.

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