Lindane
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Lindane
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| Systematic (IUPAC) name | |
| 1,2,3,4,5,6-hexachlorocyclohexane | |
| Identifiers | |
| CAS number | |
| ATC code | P03 |
| PubChem | |
| DrugBank | |
| Chemical data | |
| Formula | C6H6Cl6 |
| Mol. mass | 290.828 g/mol |
| Pharmacokinetic data | |
| Bioavailability | ? |
| Protein binding | 91% |
| Metabolism | ? |
| Half life | 18 hours |
| Excretion | ? |
| Therapeutic considerations | |
| Pregnancy cat. |
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| Legal status | |
| Routes | ? |
Lindane is an insecticide, also known as gamma-hexachlorocyclohexane (HCH) and benzene hexachloride (BHC). It has an LD50 of 88 mg/kg, and is suspected of being a carcinogen. Its method of action is via interfering with the GABAa receptor/Cl- channel. It has been used in agriculture and in pharmaceutical products for the treatment of headlice and scabies.
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[edit] Bans
Lindane is banned in 52 countries, and under review for addition to the Stockholm Convention On Persistent Organic Pollutants.[1] In the U.S. the EPA recently banned all agricultural uses of lindane, but the FDA still allows lindane to be used in pharmaceuticals products for the treatment of headlice and scabies. California has banned all uses of lindane, and there is a bill in the New York State Assembly and Senate to ban its use in headlice products and limit its use on scabies. Its use is restricted or banned in most of Europe and many developing countries.[2] Mexico is the next of many nations who are banning lindane. Larger than the issue of toxicity of lindane itself, the bans also have to do with the other isomers of HCH produced as by-products, which have little or no use. These isomers were stockpiled in open heaps by lindane producers in the 1940s and 1950s leading to severe ground and water contamination.
[edit] Environmental Contamination
Lindane is volatile with roughly 90% entering the atmosphere and ultimately being deposited in rain. In 1992 5.5 mg/L of lindane was detected in rain in Oxfordshire.[3]
Like other agricultural pesticides, lindane is very easily introduced into the water and food supply of an area through rainfall; this can lead to low-level lindane poisoning amongst the local community. A chief symptom of this is a tic causing occasional flickering of the eyelid; other than this minor discomfort, such levels of poisoning are not harmful. Lindane has caused seizures, blood disorders, and brain cancer in children, and is linked to both breast cancer and Parkinson's disease.[citation needed]
[edit] Risk for younger or smaller individuals and elderly
Lindane is contraindicated for use in neonates and should be used with extreme caution in children and in individuals weighing less than 50 kg (110 lbs). Among adverse event reports in which the outcome was serious (resulted in hospitalization, disability or death), the very young and the elderly appeared to be more susceptible to Lindane’s adverse effects and had worse outcomes.
Animal studies have demonstrated that younger animals are more susceptible to the neurologic side effects seen with Lindane use. In addition, smaller children have a larger body surface to volume ratio that may result in proportionately larger risk of systemic exposure. For this reason, Lindane has long been contraindicated for use in neonates. It is not known whether the developing nervous system of children also increases their susceptibility to neurologic toxicity.
[edit] Other populations at risk
Patients who have conditions, such as HIV infection, or take certain medications that may lower the seizure threshold should be prescribed Lindane with caution. They may be at greater risk for serious adverse events. The new Lindane label lists examples of some of these conditions and medications. The label also highlights special precautions for use of Lindane in women who are breastfeeding infants.
There are case reports of neurologic adverse events in nursing home patients treated with Lindane. Factors that may have increased their susceptibility to these adverse events include concomitant medications, underlying medical conditions, and advanced age. Special consideration should be given prior to treating this population with Lindane, even if they are greater than 50 kg.
[edit] Use
Lindane is no longer manufactured in the US, but it is imported by Morton Grove Pharmaceuticals who formulates lindane shampoo and lotion. In the US these formulations are sold exclusively by Alliant Pharmaceuticals[4] who sells pediatric medications, even though lindane is to be used with extreme caution in anyone under 110 pounds (7 stone 12 lbs or 50 kg). It is sold in a one-percent formulation as Kwell shampoo and lotion (among other brand names, also generically), used to treat human scabies infection, head lice and other ectoparasites. It has recently been banned for the treatment of head lice in California. In the United States, the Food and Drug Administration requires these products be labeled with prominent warnings about possible neurotoxicity, particularly in young patients. Even though the FDA has blackboxed lindane, it is still being prescribed for children and the elderly, whose skin is more permeable and vulnerable to its toxic effects. Medicaid, Medicare, and many state-funded health care systems still have lindane on their formularies, even though there are many safer and more effective treatments available.
Alliant Pharmaceuticals only sells lindane in 2 oz (70 g) bottles which is an amount for a large adult, when the FDA states it is to be sold in one and two ounce bottles, so children are still given a very high dosage of lindane which is the least effective and most toxic of all headlice treatments.[citation needed] Scientists report that lindane is currently among the least effective means to control lice and scabies. In a recent article, researchers studying the effectiveness of lindane for lice control "strongly recommend its removal from the market." In an informal survey conducted by the California chapter of the American Academy for Pediatrics, doctors report that they had stopped using lindane even before the California ban because of "low efficacy and high toxicity."
Lindane has little if any role in the treatment of head lice. Studies have documented its poor pediculicidal and ovicidal activity, and it is potential neurotoxicity by Edward A. Bell, PharmD, BCPS Special to Infectious Diseases in Children.[citation needed] It also had the slowest pediculicidal and least effective ovicidal activity compared with three other approved pediculicides (i.e., 1% permethrin, 0.3% pyrethrin, and 0.5% malathion)Centers for Disease Control and Prevention.[citation needed]
[edit] See also
[edit] References
- ^ Persistent Organic Pollutants Review Committee
- ^ Pesticide Action Network map of Lindane bans and restrictions
- ^ Harris GL, et al, Pesticide application and deposition - their importance to pesticide leaching to surface water, Proceedings of the Brighton Crop Protection Conference: Pests and diseases - 1992, Volume 2, 477-486, BCPC 1992. (via [1])
- ^ Alliant Press Release, June 1, 2005
- This article is based in part on the public domain US government document at FDA.gov.
