- Definition. - An alkaloid, C22H15NO6, obtained from colchicum. Although classed with the alkaloids, colchicine has an acid reaction.

Character. - Pale-yellow leaflets or a pale-yellow amorphous powder, turning darker on exposure to light, having an odor suggesting damp hay, and a very bitter taste. Solubility. - Soluble in water (l; 22) and readily so in alcohol. Incompatibility. - Colchicine is precipitated from solution by tannic acid. Dose. - Average dose: 1/128 grain (0.0005 Gm. = 0.5 milligramme), U. S. P.