Assessment of the pharmaceutical quality of omeprazole capsule brands marketed in Egypt

The pharmaceutical quality of 7 local omeprazole capsule brands in Egypt was assessed relative to the proprietary product [Losec[R]]. Drug content, content uniformity, drug release [using USP test for enteric coated articles and a modified release test] were determined. Products were subjected to a 3-month stability study. Of the 7 brands, 6 had satisfactory drug content and content uniformity. All brands passed the USP drug release test. The modified release test proved to be more discriminative. After 3 months storage, drug content of 3 brands remained > 90% and 2 of these brands maintained drug release above 75%. Changes in pellet appearance during storage were indicative of omeprazole chemical degradation

Study of the release mechanism of a water soluble drug from hydroxypropyl methylcellulose matrices

Directly compressed tablets of pyridoxine HCl in hydroxypropylmethylcellulose [HPMC] matrices containing different polymer ratios, and in HPMC matrices containing various proportions of additives; namely, sodium alginate, pectin, veegum or kaolin or various proportions of an effervescent mixture, were prepared. A double layer floating tablet was also designed. The release characteristics of the tablets were studied in either 0.1 NCl or phosphate buffer [pH 7.4]. The data were fitted into an equation relating release rate constants responsible for diffusional and relaxational processes to determine the relative contribution of the two phenomena on the overall drug release mechanism. The release of the vitamin from the simple HPMC matrix and the one containing an effervescent mixture was slower in 0.1N HCl than in phosphate buffer. The reverse was true in the presence of the additives. The floating tablets in acid medium showed a decrease in the release rate. The formulation containing drug, HPMC, sodium alginate [1:2:0.5] can be proposed for further practical application

Preparation and evaluation of sustained release tablets of Theophylline and ephedrine hydrochloride

Compressed tablets were prepared from theophylline and /or ephedrine HCL after mixing with sodium carboxymethylcellulose [Na CMC]. The effect of polymer content in the tablets on release patterns of the studied drugs was examined in vitro. A linear relationship between 150% of tablets [time to release 50% of the drug in vitro] and the ratio of polymer content to drug was found to exist within certain limits. The order of release was determined by fitting the experimental data into a simple semiempirical equation. Tablets containing [1:0.5:1.5] theophylline and Na CMC as intra- and extra granular additive showed a linear, zero-order release and achieved 100% release within 10.5 hours. A similar release of ephedrine HCL from tablets with drug to polymer ratio of 1:2 was observed. Complete release of ephedrine HCL took place within 8 hours. Tablets of theophylline, ephedrine HCL and Na CMC at ratio of 4:1:5 showed complete release of both drugs within 7 hours