BAL in Oil, British Anti-Lewisite
Classifications: chelating agent; antidote;
Therapeutic: antidote

Pregnancy Category: C


100 mg/mL injection


Dithiol compound that combines with ions of various heavy metals to form relatively stable, nontoxic, soluble complexes called chelates, which can be excreted; inhibition of enzymes by toxic metals is thus prevented.

Therapeutic Effect

Neutralizes the effects of various heavy metals.


Acute poisoning by arsenic, gold, and mercury; as adjunct to edetate calcium disodium (EDTA) in treatment of lead encephalopathy.

Unlabeled Uses

Chromium dermatitis; ocular and dermatologic manifestations of arsenic poisoning, as adjunct to penicillamine to increase rate of copper excretion in Wilson's disease, and for poisoning with antimony, bismuth, chromium, copper, nickel, tungsten, zinc.


Hepatic insufficiency (with exception of post-arsenical jaundice); history of peanut oil hypersensitivity; severe renal insufficiency; poisoning due to cadmium, iron, selenium, or uranium; pregnancy (category C), lactation.

Cautious Use

Hypertension; oliguria; patients with G6PD deficiency; preexisting renal disease; rheumatoid arthritis.

Route & Dosage

Arsenic or Gold Poisoning
Adult/Child: IM 2.5–3 mg/kg q4h for first 2 d, then q.i.d. on third day, then b.i.d. for 10 d

Mercury Poisoning
Adult/Child: IM 5 mg/kg initially, followed by 2.5 mg/kg 1–2 times/d for 10 d

Acute Lead Encephalopathy
Adult/Child: IM 4 mg/kg initially, then 3–4 mg/kg q4h with EDTA for 2–7 d depending on response


  • Initiate therapy ASAP (within 1–2 h) after ingestion of the poison because irreversible tissue damage occurs quickly, particularly in mercury poisoning.
  • Give by deep IM injection only. Local pain, gluteal abscess, and skin sensitization possible. Rotate injection sites and observe daily.
  • Determine if a local anesthetic may be given with the injection to decrease injection site pain.
  • Handle with caution; contact of drug with skin may produce erythema, edema, dermatitis.
  • Note: Presence of sediment in ampule reportedly does not indicate drug deterioration.

Adverse Effects (≥1%)

CNS: Headache, anxiety, muscle pain or weakness, restlessness, paresthesias, tremors, convulsions, shock. CV: Elevated BP, tachycardia. Special Senses: Rhinorrhea; burning sensation, feeling of pain and constriction in throat. GI: Nausea, vomiting; burning sensation in lips and mouth, halitosis, salivation; abdominal pain, metabolic acidosis. Urogenital: Burning sensation in penis, renal damage. Other: Pains in chest or hands, pain and sterile abscess at injection site, sweating, reduction in polymorphonuclear leukocytes, dental pain.

Diagnostic Test Interference

I131 thyroid uptake values may be decreased if test is done during or immediately following dimercaprol therapy.


Drug: Iron, cadmium, selenium, uranium form toxic complexes with dimercaprol.


Peak: 30–60 min. Distribution: Distributed mainly in intracellular spaces, including brain; highest concentrations in liver and kidneys. Elimination: Completely excreted in urine and bile within 4 h. Half-Life: Short.

Nursing Implications

Assessment & Drug Effects

  • Monitor vital signs. Elevations of systolic and diastolic BPs accompanied by tachycardia frequently occur within a few minutes following injection and may remain elevated up to 2 h.
  • Note: Fever occurs in approximately 30% of children receiving treatment and may persist throughout therapy.
  • Monitor I&O. Drug is potentially nephrotoxic. Report oliguria or change in I&O ratio to physician.
  • Keep urine alkaline to reduce possibility of renal damage during elimination of dimercaprol chelate.
  • Check urine daily for albumin, blood, casts, and pH. Blood and urinary levels of the metal serve as guides for dosage adjustments.
  • Minor adverse reactions generally reach maximum 15–20 min after drug administration and subside in 30–90 min. Ephedrine or an antihistamine is sometimes administered to prevent symptoms.

Patient & Family Education

  • Drink as much fluid as the physician will permit.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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