The purpose of this study was to obtain information on the photochemical properties of ketoconazole, an antifungal agent. Photodegradation of ketoconazole in solution and shampoo under exposure to UV-C (254 nm) and UV-A (352 nm) radiations as well as daylight was monitored by HPLC. Separation of ketoconazole from its degradation products was obtained with monoisopropylamine - methanol (2:500 v/v) and amonium acetate- water (1:200 w/v) (7:3 v/v) as mobile phase on a LiChrospher® 100 column RP-8, 5 μm (150 mm x 4.6 mm) and a flow rate of 1 ml/min. The main protodegradation products: (cis-1-acetyl-4-{4-[[2-(2-chlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3- dioxolan-4-yl]methoxy]phenyl}piperazine and (cis-1-acetyl-4-{4-[[2-(4-chlorophenyl)-2-(1H-imidazol- 1-ylmethyl)-1,3-dioxolan-4-yl]methoxy]phenyl} piperazine, were isolated and characterized by HPLC-MS and NMR spectrometry. The results indicated photodechlorination of ketoconazole when exposed to light and a significant decrease in antifungal activity.Colegio de Farmacéuticos de la Provincia de Buenos Aire
