Photostabilization of Demeclocycline Hydrochloride with Reduced Glutathione

Abstract

Photodegradation of demeclocycline hydrochloride (DCL) in buffer solutions was studied in absence and presence of some potential photostabilizers under the influence of fluorescent light. Photolysis of DCL solutions followed first-order kinetics, DCL was more stable in acidic pH. Change in ionic strength of the buffer had no effect on the photolysis of DCL. Among the potential photostabilizers tested, reduced glutathione (GTH) was found to be the most effective photoprotective agent. Increase in GTH concentration decreased the photodegradation rate, but this decrease was not significant above 20 μg/ml GTH concentration. The photodegradation of DCL both in presence or absence of GTH was lowest at pH 4.5 citrate buffer, compared to acetate or phosphate buffer. A mixture of 50% (v/v) propylene glycol or 50% (v/v) PEG 400 in phosphate buffer did not demonstrate any photostabilizing effect. Aluminum foil-covered glass vials provided greater photoprotection compared to clear glass or amber glass vials.