Carnitine is a quaternary ammonium compound biosynthesized from the amino acids lysine and methionine.[1] In living cells, it is required for the transport of fatty acids from the cytosol into the mitochondria during the breakdown of lipids (or fats) for the generation of metabolic energy. It is often sold as a nutritional supplement.

Cobalamin may refer to several substances depending on the upper axial ligand of the cobalt ion.

Cobamamide (AdoCbl), which is also known as adenosylcobalamin and dibencozide, is, along with methylcobalamin (MeCbl), one of the active forms of vitamin B₁₂

Cyanocobalamin is an especially common vitamer of the vitamin B₁₂ family. It is the most famous vitamer of the family, because it is chemically the most air-stable, and it is the easiest to crystallize and therefore easiest to purify after it is produced by bacterial fermentation. The cyanide is added to the molecule by activated charcoal columns in purification.