Résumé
In this work a stability indicating TLC densitometric method for the determination of leflunomide [LEF] in presence of its induced alkaline degradation product and a stability sudy of LEF in different media by HPLC method are presented. The proposed TLC densitometric method is based on the separation of LEF from its alkaline degradation product by TLC followed by densitometric measurement of the spots of the intact drug at 29 nm. Separation is performed at silica gel F254 [20 x 20 cm] plates using methanol: acetonitrile: distilled water [35:40:25] as a developing system. The method is found applicable for the determination of intact LEF over a concentration range 5-60 microg/spot with mean percentage accuracy 100.52 +/- 1.39. The proposed method is successfully applied for the determination of LEF in pure form, in laboratory prepared mixture and in pharmaceutical formulation. The validity of the method was assessed applying the standard addition technique. The results obtained agreed statistically with those obtained by the reported method. The second part is stability study of LEF in pure form in different media by HPLC method