[The photostability of hydrocortisone injection]

This experiment was designed to make known wether the photostability of drugs in daylight can be obtained from lamplight exposure.

A self made cumulative illuminometer via pulse counting method was used for measuring cumulative illuminance of daylight to investige the photodegradation of Hydrocortisone injection in various lamp light and daylight; the equivalent influences of different light sources on the photostability of the injection were obtained, and the shelf-life in indoor daylight of the drug was predicted.

The photodegradation of Hydrocortisone injection obeys zero order kinetics: C = C0-kEt; the shelf-life in indoor daylight of the injection in nude ampoules was predicted as 36 days and is comparable to 35 days in a long-term storage test.

The photostability of drugs in daylight can be obtained from lamplight exposure experiment.