The effect of the photodecomposition of chlorpromazine on lecithin monolayers.

Chlorpromazine hydrochloride (cpz) is decomposed when irradiated with ultraviolet light, forming H+, hydrochloric acid, chlorpromazine sulphoxide and 2-hydroxypromazine. The order of the reaction (as measured by the expansion that is produced in a lecithin/cpz monolayer) varies between zero and about 3/4. The results have been used to explain some of the adverse side effects that are observed when patients are treated with cpz.