- Hydroxocobalamin is a form of vitamin B₁₂, a water-soluble vitamin that plays a critical role in red blood cell formation, neurological function, and DNA synthesis.
- It is one of several cobalamin derivatives, distinguished by having a hydroxyl group (-OH) attached to the central cobalt atom of the corrin ring structure.
- Hydroxocobalamin is used both as a nutritional supplement and as a life-saving antidote for cyanide poisoning.
- In the human body, hydroxocobalamin is converted into two active coenzyme forms: methylcobalamin and adenosylcobalamin. These coenzymes are essential in metabolic pathways such as the conversion of homocysteine to methionine and the metabolism of fatty acids and amino acids. A deficiency in vitamin B₁₂ can lead to megaloblastic anemia, neurological damage, and elevated homocysteine levels, which are associated with cardiovascular disease.
- One of the most critical medical uses of hydroxocobalamin is its role as an antidote for cyanide poisoning. Cyanide is a potent inhibitor of cellular respiration, and hydroxocobalamin works by binding directly to cyanide ions in the bloodstream. This reaction forms cyanocobalamin (vitamin B₁₂), a non-toxic compound that is then excreted in urine. Because of its rapid action and effectiveness, hydroxocobalamin is included in emergency cyanide antidote kits and is commonly used by first responders and in industrial settings where cyanide exposure may occur.
- Hydroxocobalamin is typically administered via intramuscular (IM) or intravenous (IV) injection, especially in emergency situations. It is favored over other vitamin B₁₂ forms like cyanocobalamin for injections because it remains in the body longer and is more readily converted to active forms. It is also less likely to cause allergic reactions and does not contain cyanide, unlike cyanocobalamin.
- The compound is generally well-tolerated, although some side effects may occur. A common and harmless effect is a temporary reddish discoloration of the skin and urine, due to the red color of the compound. Less commonly, allergic reactions, nausea, or increased blood pressure may be observed. Because of its water solubility, excess hydroxocobalamin is usually excreted in the urine, minimizing the risk of toxicity.
