Dimercaprol (British anti-lewisite antigen) is a metal chelating agent that is used in the treatment of arsenic, mercury, gold, and lead poisoning.

Indications of Dimercaprol:

• It is an antidote for gold, arsenic (except arsine), or acute mercury poisoning (except non-alkyl mercury), an adjunct to edetate CALCIUM disodium in acute lead poisoning.

Note: The use of dimercaprol in the management of poisoning from other heavy metals has not been validated.

Dimercaprol dose in Adults

Note: During poisoning management, premedication with a histamine H-1 antagonist (eg, diphenhydramine) is recommended.

Dimercaprol dose in the treatment of acute mild Arsenic or gold poisoning:

• Deep IM: 2.5 mg/kg every 6 hours for 2 days, then every 12 hours for 1 day, followed by once daily for 10 days.

Dimercaprol dose in the treatment of acute severe Arsenic or gold poisoning:

• Deep IM: 3 mg/kg every 4 hours for 2 days, then every 6 hours for 1 day, followed every 12 hours for 10 days.

Dimercaprol dose in the treatment of acute inorganic mercury poisoning:

• Deep IM: 5 mg/kg initially, followed by 2.5 mg/kg 1-2 times/day for 10 days.

Dimercaprol dose in the treatment of Lead poisoning:

• Deep IM: Note:
  • Chelation therapy is indicated when blood lead levels are >45 mcg/dL, however, dimercaprol is only recommended for use concurrently with edetate calcium disodium in children with lead encephalopathy or whose blood lead levels are >70 mcg/dL.
  • Chelation therapy in adults is indicated for significant symptoms with blood lead levels >50 mcg/dL. Blood lead levels ≥100 mcg/dL and/or symptoms are also an indication for chelation therapy.
• Blood lead levels ≥70 mcg/dL, symptomatic lead poisoning, or lead encephalopathy (concurrently with edetate calcium disodium):
  • 4 mg/kg every 4 hours for 2-7 days.
• Duration of therapy:
  • At least 3 days is recommended by some experts.

Note: Edetate calcium disodium should be started with the second dose of dimercaprol.

Dimercaprol dose in Childrens

Note: For poisoning management, premedication with a histamine H-1 antagonist (eg, diphenhydramine) is recommended.

Dimercaprol dose in the treatment of acute mild Arsenic or gold poisoning:

• Infants, Children, and Adolescents:

  • IM: 2.5 mg/kg/dose every 6 hours for 2 days, then every 12 hours on the third day, and once daily thereafter for 10 days.

Dimercaprol dose in the treatment of acute severe Arsenic or gold poisoning:

• Infants, Children, and Adolescents:

  • IM: 3 mg/kg/dose every 4 hours for 2 days then every 6 hours on the third day, then every 12 hours thereafter for 10 days.

Dimercaprol dose in the treatment of acute Mercury poisoning:

• Infants, Children, and Adolescents:

  • IM: 5 mg/kg initially followed by 2.5 mg/kg/dose 1 to 2 times/day for 10 days.

Dimercaprol dose in the treatment of Lead poisoning as an adjunct with edetate calcium disodium:

• Infants, Children, and Adolescents: IM:

Note: Chelation therapy is indicated in children when blood lead levels are >45 mcg/dL, however, dimercaprol is only recommended for use (in combination with edetate calcium disodium) in children with lead encephalopathy or whose blood lead levels are >70 mcg/dL.

• Blood lead levels ≥70 mcg/dL, symptomatic lead poisoning, or lead encephalopathy (in conjunction with edetate calcium disodium):
  • 4 mg/kg/dose every 4 hours for 2 to 7 days.
• Duration of therapy:
  • At least 3 days is recommended by some experts.
• Note: Edetate calcium disodium should be given with the second dose of dimercaprol.

Pregnancy Risk Factor C

• Studies on animal reproduction have not been done.
• Studies during pregnancy are not always well-controlled and ineffective.
• Lead poisoning: The amount of lead that crosses the placenta is related to the maternal plasma level.
• Lead exposure during pregnancy can lead to spontaneous abortion, preterm birth, reduced birth weight and impaired neurodevelopment.
• Negative effects can also be caused by maternal blood lead levels below 10 mcg/dL.
• Due to increased lead exposure during pregnancy, the risk of gestational Hypertension (GH) is higher
• Chelation therapy should be used in pregnancy if blood lead levels are >=45 mg/dL.
• Pregnant women who have blood lead levels greater than 70 mg/dL should consider chelation, regardless of which trimester.
• Expert opinion and other alternatives to dimercaprol are important in high-risk pregnancies.
• No matter what trimester, encephalopathy should be treated with chemo.

Dimercaprol use during breastfeeding:

• It is unknown how much dimercaprol is excreted in breast milk.
• Because dimercaprol can't be taken orally, breastfeeding infants is not recommended.
• Chelation therapy for lead poisoning in adults is not recommended if blood lead levels are greater than 50.
• If you have confirmed blood lead levels of 40 mcg/dL or more, breastfeeding is not recommended. Instead, pump and then discard breast milk until your blood lead levels drop to 40 mg/dL.
• According to WHO, breastfeeding is not advised for patients who are lactating and are being treated for lead poisoning. This includes children under 1 month old, preterm, or with low G-6-PD.
• Breastfeeding requires monitoring infants for jaundice and hemolysis.

Dose adjustment in renal disease:

No adjustment provided in the manufacturer’s labeling. Use with extreme caution or discontinue if acute renal insufficiency develops during therapy.

Dose adjustment in liver disease:

Use is contraindicated in hepatic insufficiency (except in cases of post-arsenical jaundice).

Side effects of Dimercaprol:

• Cardiovascular:

  • Chest Pain
  • Hypertension (Dose-Related)
  • Tachycardia (Dose-Related)

• Central Nervous System:

  • Anxiety
  • Burning Sensation (Lips, Mouth, Throat)
  • Headache
  • Nervousness
  • Paresthesia (Hand)

• Dermatologic:

  • Diaphoresis

• Gastrointestinal:

  • Abdominal Pain
  • Nausea
  • Salivation
  • Sore Throat
  • Vomiting

• Genitourinary:

  • Burning Sensation Of The Penis

• Hematologic & Oncologic:

  • Leukopenia (Polymorphonuclear)

• Infection:

  • Abscess

• Local:

  • Pain At Injection Site

• Neuromuscular & Skeletal:

  • Weakness

• Ophthalmic:

  • Blepharospasm
  • Conjunctivitis
  • Lacrimation

• Renal:

  • Renal Insufficiency (Acute)

• Respiratory:

  • Pharyngeal Edema
  • Rhinorrhea
  • Throat Irritation

• Miscellaneous:

  • Fever

Contraindications to Dimercaprol:

Hepatic insufficiency (except for arsenic poisoning).

Warnings and precautions

• Nephrotoxicity:

  • Patients with nephrotoxicity should not take dimercaprol.
  • An alkaline pH in the urine is important to protect your kidneys. It prevents the dimercaprol-metal compound from being broken down.
  • If treatment is interrupted by renal impairment, it should be stopped immediately.
  • Hemodialysis can remove dimercaprol-metal chlorate from patients with kidney dysfunction.

Dimercaprol: Drug Interaction

Note: Drug Interaction Categories:

• Risk Factor C: Monitor When Using Combination
• Risk Factor D: Consider Treatment Modification
• Risk Factor X: Avoid Concomitant Use

Monitoring parameters:

• Infusion reactions
• RFTs
• Urine pH
• For lead poisoning: Blood lead levels (baseline and 7-21 days after completing chelation therapy)
• Hemoglobin or hematocrit
• Iron status, free erythrocyte protoporphyrin or zinc protoporphyrin
• Neurodevelopmental changes
• For arsenic poisoning: Urine arsenic levels

How to administer Dimercaprol?

• Dimercaprol should be given by deep IM injection.
• Rotate injection sites. In order to protect kidney functions, an alkaline urine pH should be maintained.
• The administration should be done in a separate site from edetate calcium disodium during the management of lead poisoning.

Mechanism of action of Dimercaprol:

A combination of sulfhydryl group with ions of various heavy metals results in the formation of relatively stable, nontoxic, soluble chelates that are excreted in the urine.

Absorption:

• IM: Rapid.
• Oral: Not absorbed.

Distribution:

• To all tissues including the brain.

Metabolism:

• Hepatic; rapid to inactive metabolites.

Time to peak serum:

• 0.5-1 hour.

Excretion:

• Urine and feces via the bile.

International Brands of Dimercaprol:

• Bal in Oil
• A.L.

Dimercaprol Brand Names in Pakistan:

No Brands Available in Pakistan.