Preparation, Characterization and In-vitro Evaluation of Microcapsules for Controlled Release of Diltiazem Hydrochloride by Ionotropic Gelation Technique.

The problems of frequent administration and variable low bioavailability after oral administration of conventional dosage forms of diltiazem can be attenuated by designing it in the form of microcapsules which would facilitate intimate contact with the absorption surface and thereby improve and enhance the bioavailability. Diltiazem-loaded microcapsules were successfully prepared by ionotropic gelation technique employing Sodium carboxy methylcellulose, Xanthan gum as rate controlling polymers and Aluminium chloride as cross linking agent. Microcapsules obtained were discrete, spherical, free flowing and showed a maximum encapsulation efficiency of 91.20 ± 0.08%. Particle size of the microcapsules was found to be in the range of 1009 – 1311 μm. Interaction studies performed using FTIR spectroscopy revealed that there were no drug and polymer interactions. The drug remained dispersed in the polymer matrix in amorphous state, which was confirmed by X-ray diffraction analysis. The in vitro drug release follows matrix-diffusion controlled release and the release mechanism was non-Fickian type controlled by swelling and relaxation of polymer. There was no significant change in drug content and cumulative drug release of drug-loaded microcapsules stored at different storage condition after 90 days. From the study, it was concluded that diltiazem loaded microcapsules could be successfully prepared by ionotropic gelation technique with high entrapment efficiency and prolonged release characteristics.

Effects of release modifier on Carvedilol release from Kollidon SR based matrix.

Sustained release Carvedilol matrix tablets constituting Kollidon SR were developed in this study in an attempt to investigate the effect of release modifiers on the release profile of Carvedilol from matrix. Three matrix tablet formulations were prepared by direct compression of Kollidon SR in combination with release modifier (HPMC and Microcrystalline Cellulose) and magnesium stearate. Tablets containing only Kollidon SR with the active ingredient demonstrated a rapid rate of drug release. Incorporation of HPMC in the matrix tablet prolonged the release of drug but incorporation of Microcrystalline Cellulose showed superimposable release pattern with an initial burst effect as confirmed by mean dissolution time and Higuchi release rate data. After 7 hours of dissolution, Carvedilol release from the matrix systems were 91.42%, 83.41%, from formulation F1 and F2 respectively. Formulation F3 exhibited 100 % release at 4 hours. All the tablet formulations showed acceptable pharmaco-technical properties and complied with the in-house specifications for tablet weight variation, friability, hardness, thickness, and diameter. Prepared tablets also showed sustained release property for carvedilol. The drug release mechanism from the matrix tablets of F1 and F2 was found to be followed by Fickian and F3 by Non-Fickian mechanism.

Effects of release modifier on Carvedilol release from Kollidon SR based matrix.

Sustained release Carvedilol matrix tablets constituting Kollidon SR were developed in this study in an attempt to investigate the effect of release modifiers on the release profile of Carvedilol from matrix. Three matrix tablet formulations were prepared by direct compression of Kollidon SR in combination with release modifier (HPMC and Microcrystalline Cellulose) and magnesium stearate. Tablets containing only Kollidon SR with the active ingredient demonstrated a rapid rate of drug release. Incorporation of HPMC in the matrix tablet prolonged the release of drug but incorporation of Microcrystalline Cellulose showed superimposable release pattern with an initial burst effect as confirmed by mean dissolution time and Higuchi release rate data. After 7 hours of dissolution, Carvedilol release from the matrix systems were 91.42%, 83.41%, from formulation F1 and F2 respectively. Formulation F3 exhibited 100 % release at 4 hours. All the tablet formulations showed acceptable pharmaco-technical properties and complied with the in-house specifications for tablet weight variation, friability, hardness, thickness, and diameter. Prepared tablets also showed sustained release property for carvedilol. The drug release mechanism from the matrix tablets of F1 and F2 was found to be followed by Fickian and F3 by Non-Fickian mechanism.

Formulation and evaluation of glipizide floating-bioadhesive tablets

The purpose of this study was formulation and in vitro evaluation of floating-bioadhesive tablets to lengthen the stay of glipizide in its absorption area. Effervescent tablets were made using chitosan (CH), hydroxypropyl methylcellulose (HPMC), carbopolP934 (CP), polymethacrylic acid (PMA), citric acid, and sodium bicarbonate. Tablets with 5 percent effervescent base had longer lag time than 10 percent. The type of polymer had no significant effect on the floating lag time. All tablets floated atop the medium for 23-24 hr. Increasing carbopolP934 caused higher bioadhesion than chitosan (p < 0.05). All formulations showed a Higuchi, non-Fickian release mechanism. Tablets with 10 percent effervescent base, 80 percent CH/20 percent HPMC, or 80 percent CP/20 percent PMA seemed desirable.