Dimercaprol

(BAN, rINN)
Dimercaprol Chemical formula
Synonyms: BAL; British Anti-Lewisite; Dimercaprolum; Dimerkaprol; Dimerkaproli; Dimerkaprolis. 2,3-Dimercaptopropan-1-ol.
Cyrillic synonym: Димеркапрол.

💊 Chemical information

Chemical formula: C3H8OS2 = 124.2.
CAS — 59-52-9.
ATC — V0 3AB09.
ATC Vet — QV0 3AB09.

Pharmacopoeias.

In Chin., Eur., Int., Jpn, US, and Viet.

Ph. Eur. 6.2

(Dimercaprol). A clear colourless or slightly yellow liquid. Soluble in water and in arachis oil; miscible with alcohol and with benzyl benzoate. Store at 2° to 8° in well-filled airtight containers. Protect from light.

USP 31

(Dimercaprol). A colourless or practically colourless liquid, having a disagreeable, mercaptan-like odour. Soluble 1 in 20 of water; soluble in alcohol, in benzyl benzoate, and in methyl alcohol. Store at a temperature not exceeding 8° in airtight containers. Protect from light.

💊 Adverse Effects and Treatment

The most consistent adverse effects produced by dimercaprol are hypertension and tachycardia. Other adverse effects include nausea, vomiting, headache, burning sensation of the lips, mouth, throat, and eyes, lachrymation and salivation, tingling of the extremities, a sensation of constriction in the throat and chest, muscle pains and muscle spasm, rhinorrhoea, conjunctivitis, sweating, restlessness, and abdominal pain. Transient reductions in the leucocyte count have also been reported. Pain may occur at the injection site and sterile abscesses occasionally develop. In children, fever commonly occurs and persists during therapy. Adverse effects are dose-related, relatively frequent, and usually reversible. It has been suggested that ephedrine sulfate 30 to 60 mg, given by mouth 30 minutes before each injection of dimercaprol, may reduce adverse effects; antihistamines may alleviate some of the symptoms.

💊 Precautions

Dimercaprol should be used with care in patients with hypertension or renal impairment. It should be discontinued, or continued with extreme caution, if acute renal insufficiency develops during therapy. Alkalinisation of the urine may protect the kidney during therapy by stabilising the dimercaprol-metal complex. Dimercaprol should not be used in patients with hepatic impairment unless due to arsenic poisoning. It should not be used in the treatment of poisoning due to cadmium, iron, or selenium as the dimercaprol-metal complexes formed are more toxic than the metals themselves.

G6PD deficiency.

Haemolysis has been reported1 during chelation therapy with dimercaprol and sodium calcium edetate for high blood-lead concentrations in 2 children with a deficiency of G6PD.
1. Janakiraman N, et al. Hemolysis during BAL chelation therapy for high blood lead levels in two G6PD deficient children. Clin Pediatr (Phila) 1978; 17: 485–7.

💊 Interactions

Iron supplements should not be given during dimercaprol therapy as toxic dimercaprol-metal complexes are formed.

💊 Pharmacokinetics

After intramuscular injection, maximum blood concentrations of dimercaprol may be attained within 30 to 60 minutes. Dimercaprol is rapidly metabolised and the metabolites and dimercaprol-metal chelates are excreted in the urine and bile. Elimination is essentially complete within 4 hours of a single dose.

💊 Uses and Administration

Dimercaprol is a chelator used in the treatment of acute poisoning by arsenic, gold, and mercury; it may also be used in the treatment of poisoning by antimony, bismuth, and possibly thallium. It is also used, with sodium calcium edetate, in acute lead poisoning. The sulfhydryl groups on dimercaprol compete with endogenous sulfhydryl groups on proteins such as enzymes to combine with these metals; chelation by dimercaprol therefore prevents or reverses any inhibition of the sulfhydryl enzymes by the metal and the dimercaprol-metal complex formed is readily excreted by the kidney. Since the complex may dissociate, particularly at acid pH, or be oxidised, the aim of treatment is to provide an excess of dimercaprol in body fluids until the excretion of the metal is complete. Dimercaprol should be given by deep intramuscular injection and the injections should be given at different sites. The usual initial dose is up to 18 mg/kg daily in divided doses on the first day, reducing the daily dose and the frequency of injections over the subsequent days; a minimum interval of 4 hours between doses appears to reduce adverse effects. The individual dose is determined by severity of symptoms and the causative agent. Single doses should not generally exceed 3 mg/kg but single doses of up to 5 mg/kg may be required initially in patients with severe acute poisoning. Various dosage schedules are in use. In the UK, adults may be given doses of 400 to 800 mg on the first day of treatment, 200 to 400 mg on the second and third days, and 100 to 200 mg on the fourth and subsequent days, all in divided doses; children may be given a similar dose per kg as for adults. Alternatively, the BNF recommends a dose for both adults and children of 2.5 to 3 mg/kg every 4 hours for 2 days, 2 to 4 times daily on the third day, then 1 to 2 times daily for 10 days or until recovery. In the USA, a recommended schedule for severe arsenical or gold poisoning is 3 mg/kg given at 4-hourly intervals throughout the first 2 days, 4 times on the third day, and twice on each of the next 10 days. In milder cases, 2.5 mg/kg is given 4 times daily on each of the first 2 days, twice daily on the third day, and once daily on subsequent days for 10 days or until recovery. Dimercaprol is also used with sodium calcium edetate in the treatment of lead poisoning and can be of particular value in the treatment of acute lead encephalopathy. Dimercaprol is usually started first, since sodium calcium edetate may cause lead to shift into the CNS. A suggested procedure is to give dimercaprol intramuscularly in an initial dose of 4 mg/kg, followed at 4-hourly intervals by dimercaprol 3 to 4 mg/kg intramuscularly and sodium calcium edetate; the sodium calcium edetate may be given either intravenously, or intramuscularly at a different site from the dimercaprol. Treatment may be continued for 2 to 7 days depending on the clinical response.

💊 Preparations

BP 2008: Dimercaprol Injection; USP 31: Dimercaprol Injection.

Proprietary Preparations

Rus.: Zorex (Зорекс).
Published November 03, 2018.