Corrinoids

Cyanocobalamin is a form of vitamin used to treat and prevent vitamin deficiency except in the presence of cyanide toxicity. The deficiency may occur in pernicious anemia, following surgical removal of the stomach, with fish tapeworm, or due to bowel cancer. It is given by mouth, by injection into a muscle, or as a nasal spray.

thumb|right|Corrin ring, numbered according to the 1975 IUPAC standard. Note that for consistency with the porphyrin numbering system, there is no 20 position. Positions 21-24 were numbered 20-23 in earlier literature. thumb|Vitamin B (cyanocobalamin) Corrinoids are a group of compounds based on the skeleton of corrin, a cyclic system containing four pyrrole rings similar to porphyrins. These include compounds based on octadehydrocorrin, which has the trivial name corrole.