Development of enzyme-controlled colonic drug delivery using amylose and hydroxypropyl methylcellulose: optimization by factorial design.

The aim of the present study is to develop colon-targeted drug delivery systems for diclofenac sodium which release the drug specifically and instantly at target site using amylose as a carrier. Coating formulations were designed based on the full factorial design. The evaluated responses were lag time prior to drug release and T90. Compression-coated tablets of diclofenac sodium containing various proportions of amylose and HPMC were prepared. In vitro drug release studies were done by changing pH method with enzyme. In vivo studies were done to confirm the potential of formulation to release the drug at target site. The dissolution data revealed that the ratio of polymers is very important to achieve optimum formulation. Results showed that the tablet prepared according to the above formulation released drug instantly at pH 6.8 (simulating colonic pH). An in vivo study shows that optimized formulation disintegrated in the target region. The results of this study revealed that factorial design is a suitable tool for optimization of coating formulations to achieve colon delivery. It was shown that coating formulation consisting of amylose 285 mg and HPMC 150 mg coating has the potential for colonic delivery of diclofenac sodium irrespective of change in pH in a patient with IBD.

In vitro drug release and in vivo human X-ray studies of ileo-cecal targeting budesonide fast disintegrating tablet.

Crohn's disease is a type of inflammatory bowel disease that frequently affects the ileo-cecal region of the gastrointestinal tract. For effective treatment of this disease, a site-targeting drug in the ileo-cecal region is essential. Budesonide (BD) is a synthetic, non-halogenated glucocorticoid and is the drug of choice for the treatment of Crohn's disease. The present study is an attempt to develop the dosage form of a BD tablet to achieve targeted drug release in the ileo-cecal region. The BD tablets are coated with Eudragit FS 30 D, which is a polymer that specifically dissolves at and above pH 6.8. The in vitro drug release and in vivo tablet disintegration (using X-ray radiography) were carried out. The coating process was optimized successfully. The in vitro performance of the tablet with coating thickness showed that the tablet did not disintegrate till 4.5 hours, which represents the transit time to the ileo-cecal region. In vivo studies also established that the tablet lasted till 4.5 hours. The tablet containing 0.5% superdisintegrant and 10% coating thickness was able to deliver BD effectively to the ileo-cecal region, thus making it a promising drug delivery system for the treatment of Crohn's disease.

Formulation and optimization of sustained release tablets of venlafaxine resinates using response surface methodology.

The aim of the current study was to design sustained release matrix tablets of venlafaxine hydrochloride using ion exchange resin with the incorporation of hydrophilic and hydrophobic polymer combinations. Venlafaxine HCl was loaded onto Indion 244 by batch method and then resinate were wet granulated with ethyl cellulose and blended with hydroxypropylmethylcellulose and compressed. A central composite design for 2 factors at 3 levels each was employed to systematically optimize drug release profile at 2 h and at 18 h. Hydroxypropylmethylcellulose and ethylcellulose were taken as the independent variables. Response surface plots and contour plots were drawn, and optimum formulations were selected by feasibility and grid searches. Resinate shows inadequate sustained release profile. Compressed matrices exhibited the anomalous release mechanism, as the value of release rate exponent (n) varied between 08109 and 08719, resulting in regulated and complete release until 20 h. Validation of optimization study, performed using five confirmatory runs, indicated very high degree of prognostic ability of response surface methodology, with mean percentage error as 1.152+/-1.88%. Regulated drug release study indicates that the hydrophilic and hydrophobic matrix tablets of venlafaxine resinate prepared using hydroxypropylmethylcellulose and ethylcellulose, can successfully be employed as a once-a-day oral controlled release drug delivery system.

Statistical Optimization of Sustained Release Venlafaxine HCI Wax Matrix Tablet.

The purpose of this research was to prepare a sustained release drug delivery system of venlafaxine hydrochloride by using a wax matrix system. The effects of bees wax and carnauba wax on drug release profile was investigated. A 3(2) full factorial design was applied to systemically optimize the drug release profile. Amounts of carnauba wax (X(1)) and bees wax (X(2)) were selected as independent variables and release after 12 h and time required for 50% (t(50)) drug release were selected as dependent variables. A mathematical model was generated for each response parameter. Both waxes retarded release after 12 h and increases the t(50) but bees wax showed significant influence. The drug release pattern for all the formulation combinations was found to be approaching Peppas kinetic model. Suitable combination of two waxes provided fairly good regulated release profile. The response surfaces and contour plots for each response parameter are presented for further interpretation of the results. The optimum formulations were chosen and their predicted results found to be in close agreement with experimental findings.