Description

Simple

A medication used to treat head lice.

Clinical

A parasympathomimetic organophosphate used to treat head lice.

Overview

Malathion is a parasympathomimetic organophosphate compound that is used as an insecticide for the treatment of head lice. Malathion is an irreversible cholinesterase inhibitor and has low human toxicity.

Pharmacology

Indication

For patients infected with Pediculus humanus capitis (head lice and their ova) of the scalp hair.

Pharmacodynamic

Malathion is an organophosphate insecticide commonly used to control mosquitos and other flying insects. Pharmaceutically, malathion is used to eliminate head lice. The principal toxicological effect of malathion is cholinesterase inhibition, due primarily to malaoxon and to phosphorus thionate impu... Read more

Mechanism of action

Malathion is a nonsystemic, wide-spectrum organophosphate insecticide. It inhibits acetylcholinesterase activity of most eukaryotes. Malathion is toxic to aquatic organisms, but has a relatively low toxicity for birds and mammals. The major metabolites of malathion are mono- and di-carboxylic acid d... Read more

Absorption

Malathion in an acetone vehicle has been reported to be absorbed through normal human skin only to the extent of 8% of the applied dose. Absorption may be increased when malathion is applied to damaged skin. Malathion is rapidly and effectively absorbed by practically all routes including the gastro... Read more

Protein binding

Information currently not available.

Volume of distribution

Information currently not available.

Clearance

Information currently not available.

Half life

8-24 hours

Route of elimination

Information currently not available.

Toxicity

Malathion is slightly toxic via the oral route, with reported oral LD50 values of 1000 mg/kg to greater than 10,000 mg/kg in the rat. It is also slightly toxic via the dermal route, with reported dermal LD50 values of greater than 4000 mg/kg in rats. Moderate poisoning can resu... Read more

Adverse Effects

Contraindications

  • Regions: US
  • Age Groups:
    • infant
    • neonatal

Food Interactions

    Information currently not available.

Interactions

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  • Paracetamol(acetaminophen)
  • Paxil(paroxetine)
  • Pamelor(nortriptyline)
  • Panadol(acetaminophen)
  • Patanol(olopatadine ophthalmic)
  • Pataday(olopatadine ophthalmic)
  • Parnate(tranylcypromine)
  • Pazeo(olopatadine ophthalmic)
Cenobamate
The serum concentration of Malathion can be decreased when it is combined with Cenobamate.
Dipyridamole
The therapeutic efficacy of Malathion can be decreased when used in combination with Dipyridamole.
Haloperidol
The risk or severity of QTc prolongation can be increased when Malathion is combined with Haloperidol.
Hydroxyzine
The risk or severity of QTc prolongation can be increased when Malathion is combined with Hydroxyzine.
Lefamulin
Lefamulin may increase the QTc-prolonging activities of Malathion.
Lemborexant
The serum concentration of Malathion can be decreased when it is combined with Lemborexant.
Pitolisant
Malathion may increase the QTc-prolonging activities of Pitolisant.
Trazodone
The risk or severity of QTc prolongation can be increased when Trazodone is combined with Malathion.
Ziprasidone
The risk or severity of QTc prolongation can be increased when Malathion is combined with Ziprasidone.
3 References
  1. 1 . Baker EL Jr, Warren M, Zack M, Dobbin RD, Miles JW, Miller S, Alderman L, Teeters WR: Epidemic malathion poisoning in Pakistan malaria workers. Lancet. 1978 Jan 7;1(8054):31-4.PubMed: 74508
  2. 2 . Bonner MR, Coble J, Blair A, Beane Freeman LE, Hoppin JA, Sandler DP, Alavanja MC: Malathion exposure and the incidence of cancer in the agricultural health study. Am J Epidemiol. 2007 Nov 1;166(9):1023-34. Epub 2007 Aug 23.PubMed: 17720683
  3. 3 . Edwards JW, Lee SG, Heath LM, Pisaniello DL: Worker exposure and a risk assessment of malathion and fenthion used in the control of Mediterranean fruit fly in South Australia. Environ Res. 2007 Jan;103(1):38-45. Epub 2006 Aug 17.PubMed: 16914134