UV ANALYSIS OF THE EXTENT OF PHOTO-DEGRADATION OF THREE DIFFERENT DIAZEPAM TABLET FORMULATIONS UNDER DIFFERENT LIGHT EXPOSURES

This study was designed to determine the extent of photolytic degradation of diazepam tablets, without light-protective packaging, available in the market. The UV spectroscopy method was designed and applied for this purpose. A total of 2160 tablets (each tablet contained 5 mg diazepam) of three different brand formulations A, B and C were chosen randomly. These tablets were then exposed to different indirect and direct lighting conditions i.e. normal room light condition (for 60 days), direct sunlight exposure (6 hours per day for 3 days), 25 Watt incandescent light bulb exposure and 40 Watt incandescent light bulb exposure (6 hours per day for 3 days). Samples from these light exposures were analyzed for potency determination using UV spectrophotometer and compared against the tablets kept in dark place (Control). Tablets of all three formulations showed marked degradation. The overall average degradations were 23.64%±5.53%; 28.36%±4.87%; 19.72%±4.83% and 25.40%±4.17% respectively for normal room light, direct sunlight, 25 Watt and 40 Watt incandescent bulbs whereas tablets kept in dark place showed little or no decrease in potency (0.01%±.01%). These results suggest that the diazepam tablets should be marketed in light-protected opaque packaging to retain their potency and optimum therapeutic effect. At the same time, the existing transparent packaging should also be replaced with the opaque ones by the manufacturers.