An accelerated chemical stability study of Prednisone oral suspension has been performed during 6 months. A stability indicating chromatographic method was developed and validated according to the ICH guidelines by reversed phase using a Chromolith® C-18e monolithic column 4.6 x 100 mm, water:tetrahydrofuran:methanol 73:23:4 v/v/v as mobile phase, UV detection at 243 nm and 1 mL/min flow rate. Prednisolone was used as internal standard. Prednisone drug substance was subjected to forced degradation by acid and basic hydrolysis and oxidation condition, UV-Vis radiation effect, temperature and relative humidity were studied to demonstrate the indicating capability of the chromatographic method. Two and five degradation products were detected at acid and basic forced degradation respectively. No degradation products were detected at the others studied conditions. One degradation product from Prednisone oral suspension was detected during the accelerated chemical stability study. The proposed method was adequate to determine Prednisone drug substance, Prednisone oral suspension and their degradation products. The kinetic parameters of Prednisone oral suspension under the studied conditions are also reported.

The chemical stability of enalapril drug substance and tablets was studied by a stability-indicating liquid chromatographic method. Stress testing was performed on drug substance under various conditions. Accelerated stability testing was carried out for different formulations of enalapril tablets. Chromatographic separation was achieved on a RP-18 column, using a mobile phase of methanol phosphate buffer at 1.0 mL min"1 and UV detection. Degradation of the drug substance was greater under hydrolytic conditions. After 180 days of accelerated stability testing most enalapril tablets showed more than 10% of degradation. Enalapril drug substance and tablets showed instability under stress and accelerated testing respectively, with possible implications on the therapeutic activity.