Hydroxocobalamin Accord Healthcare (Hydroxocobalamin)

Hydroxocobalamin is indicated for conditions related to vitamin B12 deficiency and cyanide toxicity.

• Vitamin B12 deficiency: Restores normal B12 levels and improves related hematologic and neurologic abnormalities.
• Pernicious anemia: Provides the necessary cobalamin to support red blood cell production in patients lacking intrinsic factor.
• Cyanide poisoning: Acts as a rapid antidote by binding cyanide ions, facilitating their conversion to less toxic thiocyanate.

• Hydroxocobalamin functions as a cofactor for the enzymes methionine synthase and methylmalonyl‑CoA mutase. By donating a methyl group, it enables the conversion of homocysteine to methionine and the metabolism of odd‑chain fatty acids, supporting DNA synthesis, red blood cell formation, and myelin maintenance. In cyanide poisoning, the cobalt centre binds cyanide to form cyanomethemoglobin, which is subsequently detoxified to thiocyanate.

Adverse reactions to hydroxocobalamin are generally infrequent but may occur after intramuscular administration.

Common Side Effects

• Injection site pain: mild discomfort or soreness at the injection site.
• Red discoloration of skin: temporary reddish hue of the skin or urine.
• Headache: mild to moderate headache following injection.
• Nausea: occasional feeling of nausea after administration.

Serious or Rare Side Effects

• Anaphylaxis: severe allergic reaction with respiratory distress.
• Hypotension: sudden drop in blood pressure post‑injection.
• Hemolysis: breakdown of red blood cells in susceptible individuals.
• Methemoglobinemia: elevated methemoglobin levels causing cyanosis.

When using hydroxocobalamin, certain precautions should be observed to ensure safety and efficacy.

• Indication confirmation: verify vitamin B12 deficiency or cyanide exposure before administration.
• Allergy assessment: screen for known hypersensitivity to cobalamin compounds.
• Renal impairment: monitor renal function as hydroxocobalamin is excreted renally.
• Pregnancy and lactation: use only if the potential benefit outweighs risk; consult a specialist.
• Concomitant medications: evaluate for possible interactions with nitrites or other cyanide‑binding agents.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Hydroxocobalamin may interact with certain drugs, affecting their efficacy or safety.

Major Interactions (Avoid)

• Nitrites: can reduce the effectiveness of hydroxocobalamin as an antidote.
• Methemoglobin‑forming agents: concurrent use may exacerbate methemoglobinemia.

Moderate Interactions (Monitor Closely)

• Anticonvulsants (e.g., phenytoin): may alter vitamin B12 metabolism.
• Chemotherapy agents (e.g., methotrexate): potential additive toxicity.
• Oral contraceptives: may affect plasma B12 levels.
• Proton pump inhibitors: can reduce absorption of oral B12, less relevant for injectable but monitor overall B12 status.