Photo-decomposition and metabolism of the phenothiazine drug perazine.

An ethanolic solution of perazine (Taxilan), degraded by photooxidation, was examined by HPLC and mass-spectroscopy. Identical degradation and oxidation products were found in vitro as reported to exist in vivo with the exception of perazine-N-oxide and 3-OH-perazine. The formation of the latter two metabolites seems to be bound to the cytochrome P-450 system. A direct, oxygen dependent formation of some metabolites is, however, suggested. Side-effects of phenothiazines such as contact allergies might be related to the formation of radicals or particular oxidation products.