dimerkaprol

Dimercaprol, also known as British anti-Lewisite (BAL), is a chelating agent with two sulfhydryl (-SH) groups. It binds certain heavy metals including arsenic, inorganic mercury, gold salts, and lead, forming stable complexes that are excreted in urine. It was developed in the 1940s as an antidote to the arsenical vesicant lewisite and earned the name British anti-Lewisite.

BAL is indicated for acute metal poisoning with arsenic, mercury, and certain gold compounds; historically it was used for lead poisoning but is less common for that indication today. It may be used in combination with other chelators, such as calcium disodium EDTA, for lead poisoning when appropriate. It is not effective against all heavy metal poisons and is generally reserved for specific indications when other chelators are ineffective or unavailable. It can also be used to treat exposure to lewisite.

Administration of BAL is by intramuscular injection as an oil-based emulsion, due to the hydrophobic vehicle. Dosing depends on body weight, severity, and institutional guidelines and is given in divided doses over 1–4 days; clinicians may adjust as toxicity improves. It should be used under close medical supervision.

Contraindications and precautions: BAL is contraindicated in individuals with peanut or soy allergy because the vehicle is typically peanut oil. It can cause hypertension, tachycardia, pain at the injection site, fever, nausea, edema, and nephrotoxicity. Hypersensitivity reactions may occur. It can mobilize metals from tissues, which may lead to redistribution to plasma and other tissues, so monitoring is essential. Use with caution in patients with renal or hepatic impairment.