Malathion is hydrolysed and detoxified by plasma carboxylesterases much more

Malathion is hydrolysed and detoxified by plasma

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the same site for 8 days (12). Malathion is hydrolysed and detoxified by plasma carboxylesterases much more rapidly in man than in insects, giving rise to selective toxicity and a low potential for toxicity in man. (13,14). A small, open study investigated the safety of four malathion head lice preparations by applying a dose to the scalp and measuring any effects on plasma and erythrocyte cholinesterase. None of the preparations has any clinical effect on either plasma or erythrocyte cholinesterase activity irrespective of single or repeat dose treatment, or whether applied to damaged or intact skin (15). Summary No studies on the passage of any of the parasiticidal agents used to treat head lice into human breast milk following topical application have been located. Wet combing has achieved cure rates of up to 57% after 14 days, but is very time consuming. Bug busting with a comb appears less effective than insecticides, but may be preferred by people wishing to avoid using chemicals. Available through NICE Evidence Search at 2
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Medicines Q&As Dimeticone has a physical action, coating the lice and disrupting their ability to manage water. There is little or no absorption of dimeticone through the skin. Percutaneous absorption of malathion is low. Malathion is rapidly destroyed by plasma cholinesterases. Wet combing or dimeticone may be used to treat head lice in breastfeeding mothers. Malathion may be used as an alternative if a traditional insecticide is required in the case of treatment failure. Theoretical considerations would indicate that the amount of drug passing into milk after topical application would be too low to present a hazard to the breastfeeding infant. Limitations There is very limited clinical data on the use of pediculocides in human lactation. Where studies have documented the passage of these agents into breast milk, it has been in the context of aerial insecticide sprays or powders used in gardening. The information relates to full term and healthy infants. Evidence in preterm infants is lacking. If the infant is pre-term, of low birth weight or has other concomitant pathology or medical problems, then specialist advice should be sought as this answer may not apply . Contact the UK Drugs in Lactation Advisory Service (UKDILAS) provided by the Trent and West Midlands Medicines Information Services References 1. Connolly M. Current recommended treatments for head lice and scabies. Prescriber 2011;22(1/2):26. 2. Anon. Update on treatments for head lice. Drug Ther Bull 2009;47:50-52. 3. Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. Accessed via on 11/05/15]. 4. Head Lice (Topic Review). Clinical Knowledge Summaries. (Last revised Feb 2015) Accessed via on 13/05/2015 Sheskey P, Cook WG and Cable CG (eds).
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  • Summer '19
  • Head louse, Pediculosis, Body louse, Dimeticone

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