Neo-Cytamen (Hydroxocobalamin Chloride)

Neo-Cytamen, a hydroxocobalamin preparation, is used in conditions where vitamin B12 activity or cyanide detoxification is required.

• Vitamin B12 deficiency: Restores normal cobalamin levels, supporting DNA synthesis and red blood cell formation in patients with dietary deficiency, malabsorption, or pernicious anemia.
• Cyanide poisoning: Binds cyanide ions to form cyanocobalamin, facilitating rapid detoxification and excretion in acute cyanide exposure.
• Megaloblastic anemia: Improves hematologic parameters by correcting cobalamin‑dependent metabolic defects.

• Hydroxocobalamin chloride acts as a cofactor for the enzymes methionine synthase and methylmalonyl‑CoA mutase, enabling methyl group transfer essential for DNA synthesis and red blood cell maturation. It also has a high affinity for cyanide ions, forming the stable complex cyanocobalamin, which is then eliminated renally, thereby detoxifying cyanide exposure.

Common Side Effects

• Injection site pain: mild to moderate discomfort at the site of administration.
• Low‑grade fever: transient temperature elevation within 24 hours.
• Headache: mild headache not requiring intervention.
• Nausea: occasional feeling of nausea post‑injection.

Serious or Rare Side Effects

• Anaphylaxis: severe allergic reaction requiring immediate medical attention.
• Hypotension or severe hypertension: abrupt blood pressure changes.
• Stevens‑Johnson syndrome: rare severe skin reaction.
• Hemolysis: destruction of red blood cells in susceptible individuals.
• Arrhythmia: irregular heart rhythm in rare cases.

Before initiating therapy, assess baseline vitamin B12 status and cyanide exposure risk.

• Assess B12 status before use: measure serum cobalamin to confirm deficiency.
• Monitor for allergic reactions: observe patient after injection for signs of hypersensitivity.
• Use with caution in renal impairment: adjust monitoring and consider renal function.
• Avoid in known hypersensitivity to cobalamin compounds: discontinue if reaction occurs.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Hydroxocobalamin may interact with several medications that affect cobalamin metabolism or hemodynamics.

Major Interactions (Avoid)

• Methotrexate: may reduce efficacy of cobalamin therapy.
• Chloramphenicol: may interfere with cobalamin metabolism.
• Nitrous oxide anesthesia: can inactivate vitamin B12, increasing risk of deficiency.

Moderate Interactions (Monitor Closely)

• Proton pump inhibitors: may decrease oral absorption (though injection bypasses this route).
• Metformin: may lower serum B12 levels, requiring periodic monitoring.
• Anticonvulsants (phenytoin, carbamazepine): may affect B12 status and require observation.