BAL
Clinical safety rating
cautionComprehensive clinical and safety monograph for BAL (BAL).
Chelating agent that forms stable complexes with heavy metals (e.g., arsenic, mercury, lead) by binding to their sulfhydryl groups, facilitating renal excretion.
| Metabolism | Primarily hepatic; undergoes oxidation and conjugation; metabolites excreted renally. |
| Excretion | Primarily renal; approximately 80% of a dose is excreted in urine as unchanged drug and metabolites within 24 hours. Biliary/fecal elimination accounts for less than 5%. |
| Half-life | Terminal elimination half-life is approximately 6.8 hours (range 4–13 hours). In patients with impaired renal function, half-life may be prolonged. |
| Protein binding | BAL is extensively bound to plasma proteins, primarily albumin, with protein binding >90%. |
| Volume of Distribution | Volume of distribution is approximately 3.5 L/kg, indicating extensive distribution into tissues, including brain and intracellular spaces. |
| Bioavailability | BAL is not administered orally due to poor absorption and gastrointestinal irritation. Given intravenously, bioavailability is 100%. Intramuscular bioavailability is similar but with slower absorption. |
| Onset of Action | Intravenous administration: onset of clinical effect is within minutes (peak chelation effect). Intramuscular administration (historical use): onset in 1–2 hours. |
| Duration of Action | Duration of chelation effect is approximately 4–6 hours post intravenous dose, corresponding to the distribution and early elimination phases. Multiple doses are required for sustained effect. |
| Molecular Weight | 124.21 |
3-5 mg/kg IM every 4 hours for 2 days, then every 6 hours for 1 day, then every 12 hours for 10 days.
| Dosage form | INJECTABLE |
| Renal impairment | GFR 10-50 mL/min: reduce frequency to every 6-8 hours; GFR <10 mL/min: reduce frequency to every 8-12 hours. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 25%; Child-Pugh C: reduce dose by 50% and monitor for hepatotoxicity. |
| Pediatric use | 3-5 mg/kg IM every 4 hours for 2 days, then every 6 hours for 1 day, then every 12 hours for 10 days; maximum 100 mg per dose. |
| Geriatric use | Start at 3 mg/kg IM every 6 hours; adjust based on renal function, monitor for hypotension and pain at injection site. |
| 1st trimester | Limited data; potential teratogenicity not fully established. Use only if clearly needed and no safer alternative. |
| 2nd trimester | Use with caution; weigh risks vs benefits. May cross placenta and cause fetal harm. |
| 3rd trimester | Avoid near term due to risk of neonatal toxicity (e.g., jaundice, hemolysis). |
Clinical note
Comprehensive clinical and safety monograph for BAL (BAL).
| Placental transfer | Crosses placenta; detected in fetal tissues. Degree of transfer is moderate to high based on animal studies. |
| Breastfeeding | Excreted into breast milk in low amounts; monitor infant for rash, hemolysis, or jaundice. Consider benefit of therapy vs risk. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Insufficient human data; animal studies suggest potential teratogenicity at high doses. Avoid in first trimester unless benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, renal function, hepatic enzymes, and complete blood count; fetal assessment by ultrasound if used in pregnancy. |
| Fertility Effects | No adequate human data; animal studies show no significant impairment at therapeutic doses. Potential for transient suppression of spermatogenesis in males. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to BAL or any componentIron therapy (concomitant use increases toxicity)Severe hepatic impairment
| Precautions | Monitor renal function and serum electrolytes during therapy., Can cause hypertension, tachycardia, and myocardial ischemia; use cautiously in cardiovascular disease., May induce hemolytic anemia in patients with G6PD deficiency., Injection site reactions and sterile abscesses may occur., Iron deficiency is a known adverse effect due to iron chelation. |
| Food/Dietary | Avoid alcohol and caffeine. Maintain adequate hydration. No specific food restrictions, but ensure iron-rich foods are avoided if concurrent iron poisoning suspected (though BAL not indicated for iron). |
| Clinical Pearls | BAL (dimercaprol) is used as a chelating agent for heavy metal poisoning, particularly arsenic, lead, and mercury. Administer deep IM only; avoid IV due to risk of hemolysis. Monitor blood pressure closely as hypertension can occur. Contraindicated in peanut allergy due to peanut oil vehicle. Administer with alkaline urine to protect kidneys. |
| Patient Advice | This medication is given as an injection into a muscle. · You may experience a metallic taste, headache, or nausea. · Report any signs of allergic reaction such as rash or difficulty breathing. · Avoid alcohol while on this medication. · Do not drive or operate heavy machinery until you know how this drug affects you. |
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