British anti-Lewisite
By Domingo Tabangcura, Jr. and G. Patrick Daubert, MD
Pharmacology
The administration of BAL is typically 3-5 mg/kg intramuscularly every 4 hours
for 2-10 days depending on the toxicity. BAL is suspended in peanut oil and
therefore should be used with extreme caution in patients with peanut
allergies. The injection is painful and some physicians may elect to administer
a local anesthetic at the injection site. Peak blood levels of dimercaprol
occur within 30 to 60 minutes following intramuscular doses.[9] The half-life
is very short, with complete excretion within 4 hours.[9] The highest
concentrations of BAL are found in the liver and kidneys (animal studies).[10]
The metabolism of BAL has not been well-described. BAL not fixed to a heavy
metal may be rapidly metabolized to inactive products, some of which are
glucuronide-conjugated.[11] There is also an oxidized from of BAL found in the
urine and is appears to be an active metabolite.[9] If the BAL-metal complex is
oxidized, the metal is released and can exert its toxic effect again;
therefore, the dosage of BAL must be high enough to assure the excess of free
BAL in body fluids until the metal is completely excreted.[11]