In vitro evaluation of domperidone mouth dissolving tablets.

In the present research work mouth dissolving tablets of domperidone were developed with superdisintegrants like crospovidone, croscarmellose sodium and sodium starch glycollate in various concentrations like 3%, 4% and 6% w/w by direct compression method. All formulations were evaluated for physical characteristics of compressed tablets such as weight variation, hardness, friability, content uniformity, in vitro disintegration time, wetting time and in vitro dissolution study. Among all, the formulation F3 (containing 6% w/w concentration of crospovidone) was considered to be the best formulation, having disintegration time of 9 s, wetting time of 15 s and in vitro drug release of 99.22% in 15 min.

Nimesulide-modified gum karaya solid mixtures: preparation, characterization, and formulation development.

Solid mixtures of nimesulide (NS) and modified gum karaya (MGK) were prepared to improve the dissolution rate of NS. The effect of drug-carrier ratio on dissolution rate of NS was investigated by preparing the solid mixtures of different ratios by cogrinding method. Solid mixtures were also prepared by physical mixing, kneading, and solid dispersion techniques to study the influence of method of preparation. Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), and equilibrium solubility studies were performed to explain the results of in vitro dissolution rate studies. It was clearly evident from the results that the NS dissolution rate was dependent on the concentration of MGK in the solid mixtures, and optimum weight ratio was found to be 1:4 (NS:MGK). Though the dissolution rate of NS from all solid mixtures prepared by different methods improved significantly, maximum improvement in dissolution rate was observed with solid dispersions. The order of methods basing on their effect on dissolution efficiency is solid dispersion > kneading > cogrinding > physical mixing > pure NS. Tablets of pure drug and solid mixtures (1:4 w/w, NS:MGK) were prepared. Though the best results from the dissolution test were obtained for the tablets containing solid dispersions, tablets containing cogrinding mixture were found to be suitable, from a practical point of view, for commercialization.

Studies on the applicability of tamarind kernel powder as a carrier in the dissolution enhancement of poorly water soluble drug, celecoxib.

In the present investigation, tamarind kernel powder (TP) was evaluated for its suitability as a carrier to improve the dissolution rate of poorly water-soluble drug, celecoxib (CC). The influence of polysaccharide concentration and method of preparation of solid mixtures on dissolution rate was investigated. Solid mixtures of CC and TP were prepared in different ratios (1:1, 1:4 & 1:9 w/w, CC:TP) using co-grinding technique to test the effect of polysac-charide concentration. Four different methods namely (i) physical mixing method (ii) co-grinding method (iii) kneading method and (iv) solvent deposition method were used to assess the effect of method of preparation. Solid mixtures were characterized by Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD) studies and solubility studies. Dissolution rate of CC was increased as the TP concentration increased and optimum weight ratio was found to be 1:4 (CC:TP). It was found that method of preparation of solid mixtures significantly effected the dissolution rate of CC from solid mixtures. The order of products basing on dissolution efficency is solvent deposition > co-grinding > kneading > physical mixing > pure CC. Among all the methods, though the solvent deposition technique improved the dissolution rate to maximum, co-grinding technique was found to be suitable from practical point of view and commercialization.

Influence of colon degradation of polysaccharide on the oral bioavailability of theophylline from controlled release hydrophilic matrices.

Hydrophilic matrices of gum karaya (GK) and guar gum (GG) using theophylline (TH) as a model drug were prepared for oral controlled release. In vitro release studies were performed for these matrix systems to find out the suitable drug-carrier ratio, which extend the drug release up to 24 h. Promising matrix systems were subjected for in vitro degradation studies in the presence of rat caecal contents. These matrices were also evaluated for their in vivo performance in healthy human volunteers. Matrix systems containing 40% w/w of polysaccharide (GK or GG) have shown uniform and similar in vitro drug release profile for 24 h in the Sorenson's phosphate buffer (pH 7.4). However, TH release from GG-TH matrix system in the presence of rat caecal contents was significantly higher than that from GK-TH matrix system. This is because of the susceptibility of GG for degradation by microorganisms present in the rat caecal content. Though there was no significant difference between the peak plasma concentration (Cmax) and time of its occurrence (Tmax) for TH from GG-TH and GK-TH matrix systems, it was found that oral bioavailability of TH from former matrix was significantly higher than that of later. Therefore, the present study disclosed that the usage of colon degradable polymer offers an advantage in the design of controlled release dosage forms of drugs, which has good absorption properties throughout the gastrointestinal tract.