Vitamin B12 with hydroxyl group complexed to cobalt which can be displaced by cyanide resulting in cyanocobaiamin that is renally excreted.

Hydroxocobalamin is indicated for the treatment of known or suspected cyanide poisoning.

Identifying Patients with Cyanide Poisoning: Cyanide poisoning may result from inhalation, ingestion, or dermal exposure to various cyanide-containing compounds, including smoke from closed-space fires. Sources of cyanide poisoning include hydrogen cyanide and its salts, cyanogenic plants, aliphatic nitriles, and prolonged exposure to sodium nitroprusside.

The presence and extent of cyanide poisoning are often initially unknown. There is no widely available, rapid, confirmatory cyanide blood test. Treatment decisions must be made on the basis of clinical history and signs and symptoms of cyanide intoxication. If clinical suspicion of cyanide poisoning is high, Hydroxocobalamin should be administered without delay.

In some settings, panic symptoms including tachypnea and vomiting may mimic early cyanide poisoning signs. The presence of altered mental status (e.g., confusion and disorientation) and/or mydriasis is suggestive of true cyanide poisoning although these signs can occur with other toxic exposures as well.

Smoke Inhalation: Not all smoke inhalation victims will have cyanide poisoning and may present with burns, trauma, and exposure to other toxic substances making a diagnosis of cyanide poisoning particularly difficult. Prior to administration of Hydroxocobalamin, smoke-inhalation victims should be assessed for the following:

• Exposure to fire or smoke in an enclosed area
• Presence of soot around the mouth, nose or oropharynx
• Altered mental status

Although hypotension is highly suggestive of cyanide poisoning, it is only present in a small percentage of cyanide-poisoned smoke inhalation victims. Also indicative of cyanide poisoning is a plasma lactate concentration ≥ 10 mmol/L (a value higher than that typically listed in the table of signs and symptoms of isolated cyanide poisoning because carbon monoxide associated with smoke inhalation also contributes to lactic acidemia). If cyanide poisoning is suspected, treatment should not be delayed to obtain a plasma lactate concentration.

Use with Other Cyanide Antidotes: Caution should be exercised when administering other cyanide antidotes simultaneously with Hydroxocobalamin, as the safety of co-administration has not been established. If a decision is made to administer another cyanide antidote with Hydroxocobalamin, these drugs should not be administered concurrently in the same intravenous line.

Thirty mcg daily for 5 to 10 days followed by 100 to 200 mcg monthly injected intramuscularly. If the patient is critically ill, or has neurologic disease, an infectious disease or hyperthyroidism, considerably higher doses may be indicated. However, current data indicate that the optimum obtainable neurologic response may be expected with a dosage of vitamin B12 sufficient to produce good hematologic response. Children may be given a total of 1 to 5 mg over a period of 2 or more weeks in doses of 100 mcg, then 30 to 50 mcg every 4 weeks for maintenance.

Hypersensitivity to any component of this medication.

Mild transient diarrhea, itching, transitory exanthema, feeling of swelling of entire body, and anaphylaxis. A few patients may experience pain after injection of hydroxocobalamin.

The validity of diagnostic vitamin B12 or folic acid blood assays could be compromised by medications, and this should be considered before relying on such tests for therapy.

Vitamin B12 is not a substitute for folic acid and since it might improve folic acid deficient megaloblastic anemia, indiscriminate use of vitamin B12 could mask the true diagnosis.

Hypokalemia and thrombocytosis could occur upon conversion of severe megaloblastic to normal erythropoiesis with B12 therapy. Therefore, serum potassium levels and the platelet count should be monitored carefully during therapy.

Vitamin B12 deficiency may suppress the signs of polycythemia vera. Treatment with vitamin B12 may unmask this condition.

Pregnancy & Lactation

Pregnancy Category C. Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks