Determination of photostability and photodegradation products of indomethacin in aqueous media

Photochemical behaviour of indomethacin in aqueous media at 254 nm, 310 nm and sunlight was studied by HPLC. The drug exhibited a similar behaviour in all the irradiation experiments affording eight photoproducts that were separated and identified. The main photochemical routes are suggested to proceed via decarboxylation, followed by oxygenation to give an alcohol and an aldehyde and/or by solvent trapping to produce the alcohol. Photoinduced hydrolysis of CO–N bond and oxidative C2–C3 bond breakage also occur.