Kinetics of drug decomposition Part 51: Kinetics of indometacine photodegradation.

Indometacine aqueous solution degradation was studied under the influence of UV light. Spectrophotometric readings of absorbances at lambdamax = 270 nm were taken in order to follow changes of the indometacine solutions as a function of irradiation time. It was found that the degradation of indometacine under influence of UV light proceeds according a sequential reaction A k2 leads to B k2 leads to C k3 leads to D in which each individual step is a zero-order process Individual zero-order rate constants were calculated for indomatacine photodegradation under anaerobic and aerobic conditions. They indicate the first step (A leads to B) to be oxygen independent and the other processes (B leads to C leads to D) to be oxygen catalyzed.