Drug information of Hydroxocobalamin


Drug group: Antidote

Hydroxocobalamin, also known as vitamin B12a, is an injectable form of vitamin B 12 that has been used therapeutically to treat vitamin B 12 deficiency. It is also used in cyanide poisoning, Leber's optic atrophy, and toxic amblyopia
It is indicated for treatment of pernicious anemia and the prevention and treatment of vitamin B12 deficiency arising from alcoholism, malabsorption, tapeworm infestation, celiac, hyperthyroidism, hepatic-biliary tract disease, persistent diarrhea, ileal resection, pancreatic cancer, renal disease, prolonged stress, vegan diets, macrobiotic diets or other restrictive diets. Also for the treatment of known or suspected cyanide poisoning

:Dosage Forms & Strengths
Lyophilized powder for reconstitution: 5g/vial
Injection solution: 1000mcg/mL » 30mL

Mechanism of effect

Vitamin B12 exists in four major forms referred to collectively as cobalamins; deoxyadenosylcobalamin, methylcobalamin, hydroxocobalamin, and cyanocobalamin. Two of these, methylcobalamin and 5-deoxyadenosyl cobalamin, are primarily used by the body. Methionine synthase needs methylcobalamin as a cofactor. This enzyme is involved in the conversion of the amino acid homocysteine into methionine. Methionine in turn is required for DNA methylation. 5-Deoxyadenosyl cobalamin is a cofactor needed by the enzyme that converts L-methylmalonyl-CoA to succinyl-CoA. This conversion is an important step in the extraction of energy from proteins and fats. Furthermore, succinyl CoA is necessary for the production of hemoglobin, the substances that carries oxygen in red blood cells


Hydroxocobalamin is a synthetic, injectable form of Vitamin B12. Hydroxocobalamin is actually a precursor of two cofactors or vitamins (Vitamin B12 and Methylcobalamin) which are involved in various biological systems in man. Vitamin B12 is required for the conversion of methylmalonate to succinate. Deficiency of this enzyme could therefore interfere with the production of lipoprotein in myelin sheath tissue and so give rise to neurological lesions


Protein binding: Forms cobalamin (III) complexes

Half-life: 26-31 hr

Excretion: Urine


:Cyanide Poisoning
70mg/kg (usually 5 g) IV infusion over 15 minutes; additional 5 g IV may be given depending on severity of poisoning and clinical response
Not to exceed a cumulative dose of 10 g

:Vitamin B12 Deficiency
Initial: 30 mcg IM qDay for 5-10 days
Maintenance: 100-200 mcg IM qmonth; may administer higher dose if critically ill or hyperthyroidism or neurologic or infectious disease present


Consider alternative therapies, if available, in patients with known anaphylactic reactions to hydroxocobalamin or cyanocobalamin

Acute renal failure with acute tubular necrosis, renal impairment and urine calcium oxalate crystals have been reported following therapy; monitor renal function for 7 days following therapy

Substantial increases in blood pressure may occur following therapy; monitor blood pressure during treatment

Points of recommendation

IV Preparation: Reconstitute lyophilized powder with 200 mL 0.9% NaCl; resulting concentration is 25 mg/mL

:Adverse Effects
Increased blood pressure, Headache, Chromaturia, Erythema, Nausea, Decrease in lymphocytes, Local infusion site reactions, Exanthema, Itching, Diarrhea, Feeling of sweating of entire body, Anaphylaxis, Hot flashes, Peripheral edema, Chest discomfort, Memory impairment, Dizziness, Restlessness, Urticaria, Pruritus, Hematochezia, Vomiting, Abdominal discomfort, Dry throat, Throat tightness, Angioneurotic edema

Pregnancy level

Available data from cases reported in published literature and postmarketing surveillance in pregnant women are insufficient to identify a drug-associated risk for major birth defects, miscarriage, or adverse maternal and fetal outcomes

There are risks to pregnant woman and fetus associated with untreated cyanide poisoning

Cyanide readily crosses the placenta; cyanide poisoning is a medical emergency in pregnancy which can be fatal for pregnant woman and fetus if left untreated; life-sustaining therapy should not be withheld due to pregnancy

Breast feeding warning

Breastfeeding is not recommended during treatment; there are no data to determine whenbreastfeeding may be safely restarted following administration of drug; hydroxocobalamin and Vitamin B12 (which is formed when hydroxocobalamin combines with cyanide) are present in human milk; there are no data on effects of hydroxocobalamin on breastfed infant or effects on milk production

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