Permethrin cream contains Permethrin, a pyrethroid, which is a topical scabicidal agent for the treatment of infestation with Sarcoptes Scabiei (scabies). It acts on the nerve cell membrane to disrupt the sodium channel current by which the polarization of the membrane is regulated. Delayed repolarization & paralysis of the pests are the consequences of this disturbance.
Pharmacokinetics: The only approved route of administration is the topical route and there are few human data available on systemic exposure or kinetics following permethrin application to the skin. Some presystemic metabolism occurs in skin. Less than 0.5% of applied permethrin is absorbed during the first 48 hours. Absorbed permethrin is rapidly metabolized by ester hydrolysis, most likely in the liver and the products are excreted primarily in the urine.
The treatment of eczemodous like reactions with corticosteroids should be withheld prior to treatment with permethrin, as there is a risk of exacerbating the scabies infestation by reducing the immune response to the mite.
Permethrin is contraindicated in patients with known hypersensitivity to any component of pyrethroids or permethrin. Nursing staff who routinely apply permethrin may wear globes to avoid any possible irritation to the hands.
In Scabies patients, skin discomfort, usually described as burning, stinging or tingling occurs in a few individuals soon after the cream is applied. Others transient signs and symptoms of irritation including enythema, edema, eczema, rash and puritis.
In the absence of specific studies in pregnant women, its use in pregnancy should only follow medical advice. It is not known whether permethrin is excreted in human milk so it should not be used in nursing mothers.
Scabies infestation is often accompanied by pruritus, edema & erythema. Treatment with permethrin may temporarily exacerbate these conditions. Patients should be advised to avoid contact with eyes during application & to flash with water immediately if the cream gets in the eyes.
