Permethrin 1. Broad spectrum potent pyrethroid insecticide 2. Currently it is the most efficacious and the most convenient drug against both scabies and lice. 3. It acts on parasite's nerve cell membrane to disrupt the sodium channel current which causes delayed repolarisation,paralysis and death. 4. Toxicity in humans is very low. 5. Nearly 100% cure rates Permethrin 5% cream is the first-line topical therapy in the UK and the USA. Permethrin is adulticidal and ovicidal against the scabies mite and is therefore highly effective after a single application However, in practice the prescribed regimen often involves two applications. Ref Robbins 9/e pg 567