Colchicine. Molecular model of the drug colchicine (C22.H25.N.O6). This medication, sold under the brand name Colcrys, is most commonly used to treat gout. It is a toxic natural product and secondary metabolite, originally extracted from plants of the genus Colchicum (autumn crocuses). Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), nitrogen (blue) and oxygen (red).