page_title: Cyanocobalamin
section_title: In mitochondria
hierarchical_section_title: Cyanocobalamin / Metabolism / In mitochondria
caption_attribution_description: English: Schematic of enzymatic pathways involved in organic acidemias
context_page_description: Cyanocobalamin is a manufactured form of vitamin B
  ₁₂ used to treat vitamin B12 deficiency. The deficiency may occur in pernicious anemia, following surgical removal of the stomach, with fish tapeworm, or due to bowel cancer. It is less preferred than hydroxocobalamin for treating vitamin B12 deficiency. It is used by mouth, by injection into a muscle, or as a nasal spray.
  Cyanocobalamin is generally well tolerated. Minor side effects may include diarrhea and itchiness. Serious side effects may include anaphylaxis, low blood potassium, and heart failure. Use is not recommended in those who are allergic to cobalt or have Leber's disease. Vitamin B
  ₁₂ is an essential nutrient meaning that it cannot be made by the body but is required for life.
  Cyanocobalamin was first manufactured in the 1940s. It is available as a generic medication and over the counter. In the United Kingdom it costs the NHS about £2.90 per injection as of 2019. In the United States the wholesale cost of this amount was about US$0.77 in 2019. In 2017, it was the 170th most commonly prescribed medication in the United States, with more than three million prescriptions.
context_section_description: The enzymes that use B
  ₁₂ as a built-in cofactor are methylmalonyl-CoA mutase (PDB 4REQ) and methionine synthase (PDB 1Q8J).
  The metabolism of propionyl-CoA occurs in the mitochondria and requires Vitamin B
  ₁₂ (as adenosylcobalamin) to make succinyl-CoA. When the conversion of propionyl-CoA to succinyl-CoA in the mitochondria fails due to Vitamin B
  ₁₂ deficiency, elevated blood levels of methylmalonic acid (MMA) occur. Thus, elevated blood levels of homocysteine and MMA may both be indicators of vitamin B
  ₁₂ deficiency.
  Adenosylcobalamin is needed as cofactor in methylmalonyl-CoA mutase—MUT enzyme. Processing of cholesterol and protein gives propionyl-CoA that is converted to methylmalonyl-CoA, which is used by MUT enzyme to make succinyl-CoA. Vitamin B
  ₁₂ is needed to prevent anemia, since making porphyrin and heme in mitochondria for producing hemoglobin in red blood cells depends on succinyl-CoA made by vitamin B
  ₁₂.
caption: Vitamin B12 adenosylcobalamin in mitochondrion—cholesterol and protein metabolism
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