Polymethylmethacrylate Coated Alginate Matrix Microcapsules for Controlled Release of Diclofenac Sodium

Polymethylmethacrylate (PMMA) coated microcapsules of diclofenac sodium (DFS) were prepared by a modified wa-ter-in-oil-in-water (W1/O/W2) emulsion solvent evaporation method using sodium alginate (SAL) as a matrix material in the internal aqueous phase (W1).Their performance with respect to controlled release of the drug in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were evaluated, and compared with non-matrix microcapsules prepared by the conventional W1/O/W2 emulsion solvent evaporation method. Scanning electron micrographs (SEM) revealed that all the microcapsules were discrete and spherical in shape;however, the surface porosity of the matrix microcap-sules appeared to be less than that of the non-matrix microcapsules. In case of non-matrix microcapsules, an increase in the volume of water in W1 phase resulted in decrease in the drug entrapment efficiency (DEE) along with increase in release of the drug in both SGF and SIF. While in case of matrix microcapsules increase in the amount of SAL in W1 phase and concentration of the coating polymer in organic phase led to increase in DEE of the matrix microcapsules and considerable decrease in the drug release in both SGF and SIF. No interaction between the drug and any of the polymers used to prepare microcapsules was evident from Fourier transform infra-red (FTIR) analysis. The matrix microcapsules prepared using higher concentration of SAL and PMMA released the drug following zero order or Case-II transport model. The matrix microcapsules appeared to be suitable for releasing lesser amounts of DFS in SGF and providing extended release in SIF.

Development and Evaluation of a New Interpenetrating Network Bead of Sodium Carboxymethyl Xanthan and Sodium Alginate

Interpenetrating network (IPN) beads of sodium carboxymethyl xanthan (SCMX) and sodium alginate (SAL) were pre-pared by ionotropic gelation process using AlCl3 as a cross-linking agent. The effect of different formulation vari-ables like total polymer concentration, gelation time, concentration of cross-linking agent, and drug load on the extent of release of ibuprofen (IBP), a non steroidal anti-inflammatory drug, was examined. The formation of IPN structure was examined using Fourier Transform Infra-red (FTIR) analysis and the compatibility of the drug in the bead was evaluated through FTIR, X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC) analyses. While increase in the concentration of total polymer, gelation time, and drug load decreased the drug release in both acidic (pH-1.2) and phosphate buffer (PB) solution (pH-6.8), increase in the concentration of cross-linking agent tended to increase the drug release. However, from all the formulations, the drug release in acidic medium was considerably slow and a maximum 14% of the loaded drug was released in 2 h. Complete drug release was achieved in PB solution within 210 to 330 min depending upon the formulation variables. The release of the drug followed non-Fickian transport process in acidic medium and case-II transport mechanism in PB solution and these release behaviour correlated well with the kinetics of dynamic swelling of IPN beads. The study indicated that the IPN beads of SCMX and SAL could be a suitable dosage form to minimize the drug release in acidic solution and to control the drug release in PB solution depending upon the need.

Preparation and Evaluation of Rapidly Disintegrating Fast Release Tablet of Diazepam-Hydroxypropyl-β-Cyclodextrin Inclusion Complex

This study was undertaken to develop tablets of diazepam-hydroxypropyl-β-cyclodextrin inclusion complex that disintegrate within 3 minutes and release 85% of drug within 30 minutes to provide rapid action of the drug through oro-mucosal route. Formation of inclusion complex was verified using X-ray diffraction and differential scanning calorimetric studies. Enhanced of aqueous solubility, as evident from phase solubility study, and dissolution of the drug were related with the formation of inclusion complex. Among the various formulations, tablet containing inclusion complex of drug/hydroxypropyl-β-cyclodextrin in a molar ratio of 1:2, and a combination of microcrystalline cellulose/lactose in a ratio of 4:1 disintegrated in 13 seconds and released 85% drug within 9 minutes. Addition of 10% w/w polyvinyl pyrrolidone in the tablet formulation further enhanced the drug release. Accelerated stability study indicated that mean dissolution time of the drug from the tablet did not change significantly within 6 months.