Also Known As: Lindane, Kwell, Gamma-hexachlorocyclohexane, Gammaxene, Gammallin
Lindane, also known as gamma-hexachlorocyclohexane, (Î³-HCH), gammaxene, Gammallin and erroneously known as benzene hexachloride (BHC), is an organochlorine chemical variant of hexachlorocyclohexane that has been used both as an agricultural insecticide and as a pharmaceutical treatment for lice and scabies.
Lindane is a neurotoxin that interferes with GABA neurotransmitter function by interacting with the GABAA receptor-chloride channel complex at the picrotoxin binding site. In humans, lindane affects the nervous system, liver and kidneys, and may be a carcinogen. It is unclear whether lindane is an endocrine disruptor.
The World Health Organization classifies lindane as "Moderately Hazardous," and its international trade is restricted and regulated under the Rotterdam Convention on Prior Informed Consent. In 2009 the production and agricultural use of lindane was banned under the Stockholm Convention on persistent organic pollutants. A specific exemption to that ban allows it to continue to be used as a second-line pharmaceutical treatment for lice and scabies.
Lindane medications continue to be available in the US, though since 1995 they have been designated "second-line" treatments, meaning they can only be prescribed when other "first-line" treatments have failed or cannot be used. In December 2007, the FDA sent a Warning Letter to Morton Grove Pharmaceuticals, the sole U.S. manufacturer of lindane products, requesting that the company correct misleading information on two of its lindane websites. The letter said, in part, that the materials "are misleading in that they omit and/or minimize the most serious and important risk information associated with the use of Lindane Shampoo, particularly in pediatric patients; include a misleading dosing claim; and overstate the efficacy of Lindane Shampoo."
The State of California banned the pharmaceutical lindane, effective 2002, and the Michigan House of Representatives passed a bill in 2009 to restrict its use to doctors' offices. A recent analysis of the California ban concluded that a majority of pediatricians had not experienced problems treating lice or scabies since that ban took effect. The study also documented a marked decrease in lindane wastewater contamination and a dramatic decline in lindane poisoning incidents reported to Poison Control Centers. The authors concluded that, "The California experience suggests elimination of pharmaceutical lindane produced environmental benefits, was associated with a reduction in reported unintentional exposures and did not adversely affect head lice and scabies treatment."