Lindane Shampoo USP, 1%, is an ectoparasiticide and ovicide effective against Pediculosis humanis capitis (head lice), Pthirus pubis (crab lice), and their ova. In addition to the active ingredient, lindane, it contains acetone, citric acid, polysorbate 60, purified water and triethanolamine lauryl sulfate to form a shampoo base. The pH may be adjusted with citric acid and/or triethanolamine. Lindane is the gamma isomer of 1,2,3,4,5,6-hexachlorocyclohexane having the following structural formula:
C6H6Cl6 M.W. 290.83
Lindane exerts its parasiticidal action by being directly absorbed into the parasites and their ova. Feldmann and Maibach1 reported approximately 10% absorption of a lindane acetone solution applied to the forearm of human subjects and left in place for 24 hours. This vehicle was different from the approved product and the percutaneous penetration of lindane is dependent on the vehicle. Therefore, the clinical significance of these observations is unknown. Dale, et al2 reported a blood level of 290 ng/mL associated with convulsions following the accidental ingestion of a lindane-containing product. Ginsburg3 found a mean peak blood level of 28 ng/mL 6 hours after total body application of Lindane Lotion to scabietic infants and children. The half-life in blood was determined to be 18 hours.
Data available in the literature suggest that lindane has a rapid distribution phase followed by a longer beta-elimination phase.1,2,3
There are no clinical dose ranging studies for Lindane Shampoo.