Details About Overdose or Poisoning Generic Salt :: BAL, Dimercaprol
Drug Pharmacology ::
I. Pharmacology. BAL(British anti-Lewisite, dimercaprol, 2,3-dimercaptopropanol) is adithiol chelating agent that is used in the treatment of poisoning bythe heavy metals arsenic, mercury, lead, and gold. Because the vicinalthiol groups are unstable in aqueous solution, the drug is supplied asa 10% solution (100 mg/mL) in peanut oil that also contains 20% (200mg/mL) benzyl benzoate. It is administered by deep IM injection. Mostof the drug is absorbed within 1 hour and undergoes widespreaddistribution to most tissues. BAL, or its in vivo biotransformationproduct(s), is believed to form complexes with selected toxic metals,thereby minimizing the metal’s reaction with endogenous ligands andincreasing its excretion in urine. In a study of humans treated withBAL after exposure to arsenicals, peak urinary arsenic excretionoccurred in 2–4 hours and then declined rapidly.
Drug Indications ::
Acute inorganic arsenic poisoning. Limited data suggest it may also be useful in the early stages of arsine poisoning (ie, during the first 24 hours).
Mercurypoisoning (except monoalkyl mercury). BAL is most effective inpreventing renal damage if it is administered within 4 hours afteracute ingestion of inorganic mercury salts; its value in averting ortreating the acute or chronic neurologic effects of elemental mercuryvapor is unknown.
Leadpoisoning (except alkyl lead compounds). BAL has been usedconcomitantly with calcium EDTA (EDTA, Calcium [Calcium Disodium EDTA,Calcium Disodium Edetate, Calcium Disodium Versenate]) in the treatmentof pediatric lead encephalopathy, where the joint regimen has beenassociated with an accelerated decline in blood lead levels andincreased urinary lead excretion. Note: BAL is not for use as a single-drug regimen in lead poisoning.
Gold.BAL has been associated with an increase in urinary gold excretion andclinical improvement in patients treated for adverse dermatologic,hematologic, or neurologic complications of pharmaceutical goldpreparations.
Drug Contra-Indications ::
Because BAL is dispensed in peanut oil, avoid use in patients with peanut allergy.
Usewith caution in patients with hepatic and renal impairment. A fewreports suggest that dimercaprol or its metabolites are dialyzable andthat BAL increases the dialysis clearance of mercury in patients withrenal failure.
BAL has caused hemolysis in patients with G-6-PD deficiency.
Because it is given by IM injection, use with caution in patients with thrombocytopenia or coagulopathies.
Drug Adverse Effects ::
IV. Adverse effects
Local pain at injection site; sterile or pyogenic abscess formation.
Dose-relatedhypertension, with or without tachycardia. Onset, 15–30 minutes;duration, 2 hours. Use with caution in hypertensive patients.
Other adverse symptoms. Nauseaand vomiting, headache; burning sensations in the eyes, lips, mouth,and throat sometimes accompanied by lacrimation, rhinorrhea, orsalivation; myalgias; paresthesias; fever (particularly in children); asensation of constriction in the chest; and generalized anxiety.Central nervous system depression and seizures have occurred inoverdose.
Use in pregnancy.FDA category C (indeterminate) (see Table III–1). High doses of BAL areteratogenic and embryotoxic in mice. The safety of BAL in humanpregnancy is not established, although it has been used in a pregnantpatient with Wilson’s disease without apparent harm. It should be usedin pregnancy only for life-threatening acute intoxication.
E. Redistribution of metals to the brain. Despiteits capacity to increase survival in acutely poisoned animals, BAL hasbeen associated with redistribution of mercury and arsenic into thebrain. Avoid use in chronic elemental mercury poisoning or alkyl (eg,methyl) mercury poisoning, where the brain is a key target organ.
Drug Lab Interactions ::
Drug or laboratory interactions
Because a toxic complex with iron may be formed, avoid concurrent iron replacement therapy.
BAL may abruptly terminate gold therapy–induced remission of rheumatoid arthritis.
Drug Dose Management ::
Dosage and method of administration (adults and children)
Arsenic, mercury, and gold poisoning. GiveBAL, 3 mg/kg deep intramuscular injection every 4–6 hours for 2 days,then every 12 hours for up to 7–10 days if the patient remainssymptomatic and/or metal levels remain highly elevated. In patientswith severe arsenic or mercury poisoning, an initial dose of up to 5mg/kg may be used. Consider changing to oral succimer (Succimer [DMSA])or oral unithiol (Unithiol [DMPS]) once the patient is stable and ableto absorb an oral formulation. Note: Intravenousunithiol (see Unithiol [DMPS]) has a more favorable therapeutic indexthan BAL and may be a preferable alternative in the treatment of acutearsenic or mercury intoxication.
Lead encephalopathy(only in conjunction with calcium EDTA therapy [see EDTA, Calcium(Calcium Disodium EDTA, Calcium Disodium Edetate, Calcium DisodiumVersenate)]). For acute pediatric lead encephalopathy, some cliniciansinitiate treatment with BAL, 3–4 mg/kg IM (75 mg/m2), followed in 4 hours by concomitant use of calcium EDTA and BAL, 3–4 mg/kg (75 mg/m2) every 4–6 hours for up to 3 days.
Arsine poisoning (seeArsine). Consider the use of BAL, 3 mg/kg IM every 4–6 hours for 1 day,if it can be begun within 24 hours of the onset of arsine poisoning.
Lewisite burns to the eye. Create a 5% solution of BAL by diluting the 10% ampule 1:1 in vegetable oil and immediately applyto the surface of the eye and conjunctivae. Parenteral treatment mayalso be necessary to treat systemic effects (see WarfareAgents—Chemical).
Drug Chemical Formulations ::
Parenteral (for deep IM injection only; must not be given as IV). BAL in oil, 100 mg/mL, 3-mL ampules.
The suggested minimum stocking level to treat a 70-kg adult for the first 24 hours is 1800 mg (six ampules).