Reconstituted powder for suspension of antitubercular drugs formulated as microspheres for pediatric use

The aim of the present investigation was to develop a novel dosage form of rifampicin and isoniazid to minimize degradation of rifampicin in acidic medium, to modulate the release of rifampicin in the stomach and isoniazid in the intestine, and to provide pediatric compliance. Rifampicin slowly diffuses out through this hydrogel matrix, thereby sustaining its release (50.08%). The release of isoniazid was thus very low in an acidic environment, i.e. simulated gastric fluid (SGF) pH 1.2 (18.98%), while in simulated intestinal fluid (SIF) pH 7.4 the release was sustained and prolonged (76.98%). Good results were obtained for a period of 36 h in SIF pH 7.4 with isoniazid-alginate microspheres. The drug content was calculated on the basis of the drug entrapment efficiency of the individual microsphere formulation (gelatin, 82.32% and sodium alginate blends, 89.31%). Results revealed that an optimized formulation had a sedimentation volume of 0.4. This optimized formulation was found to be stable. Degradation of isoniazid was faster than that of rifampicin. The degradation rate constant at 25°C was found to be 1.9286 × 10(-4) (day-1), so the formulation was predicted to have a shelf life of 1.518 years.