BAL has an LD50 in mice via intraperitoneal administration of 90 to 180 mg/kg, which is significantly lower than that of CaNa2EDTA at 4000 to 6000 mg/kg, succimer at 2480 mg/kg, and DMPS at 1100 to 1400 mg/kg.2
Less than 1% of 700 IM injections resulted in minor reactions, such as pain at the injection site, among patients who received 2.5 mg/kg of BAL every 4 to 6 hours for 4 doses.13 When doses of 4 mg/kg and 5 mg/kg were given, the incidence of adverse effects rose to 14% and 65%, respectively.16 At these higher doses, the following symptoms were reported in decreasing order of frequency: nausea, vomiting, headache, burning sensation of lips, mouth, throat, and eyes, lacrimation, rhinorrhea, salivation, muscle aches, burning and tingling of extremities, tooth pain, diaphoresis, chest pain, anxiety, and agitation.27 These effects were maximal within 10 to 30 minutes of exposure and usually subsided within 30 to 50 minutes.16 Elevations in systolic and diastolic blood pressure and tachycardia commonly occurred and correlated with increasing doses.23,30 Thirty percent of children given BAL may develop a fever that can persist throughout the therapeutic period.23 In addition, in children, a transient reduction in the percentage of polymorphonuclear leukocytes may also occur.23 Doses above 5 mg/kg should not be administered because of the high risk of adverse reactions. Doses above 25 mg/kg can be expected to produce a hypertensive encephalopathy with convulsions and coma.45
BAL is not very effective in the presence of arsenic-induced hepatotoxicity.28 Moreover, in rats, preexistent hepatotoxicity was exacerbated when BAL was used for treatment of arsenic poisoning. Therefore, unless the hepatotoxicity is considered to be arsenic induced, hepatic dysfunction is a contraindication to BAL use.35 BAL should not be used for patients poisoned by methylmercury because animal studies demonstrate a redistribution of mercury to the brain.5,23
Because dissociation of the BAL–metal chelate will occur in acidic urine, the urine of patients receiving BAL should be alkalinized with hypertonic sodium bicarbonate to a pH of 7.5 to 8.0 to prevent kidney liberation of the metal.23 BAL should be used with caution in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, as it may cause hemolysis22; a risk-to-benefit analysis must be made because G6PD-deficiency syndromes are variably expressed. In addition, chelators are relatively nonspecific and may bind metals other than those desired, thus causing deficiency of an essential metal. For example, BAL given to mice increased copper elimination to three times normal.11 BAL is formulated in peanut oil; therefore, the patient should be questioned regarding any known peanut allergy and a risk-benefit analysis undertaken. Limited evidence suggests that iron supplements should not be given to patients who are receiving BAL because the BAL–iron complex appears to cause severe vomiting and decreases metal chelation.14,15,18
Unintentional intravenous (IV) infusion of BAL could theoretically produce fat embolism (peanut oil), lipoid pneumonia, chylothorax, and associated hypoxia.38
Dimercaprol is pregnancy category C.8 There have not been any animal studies evaluating the effects of BAL on reproduction. It is not known whether BAL is harmful to a fetus or is capable of affecting reproduction capability.8 There are no data in human poisoning in pregnancy, and BAL should only be administered to a pregnant woman if clearly indicated.8
No data address whether BAL or its chelates are excreted in human breast milk.