Some Factors Affecting the Release of Drug from Membrane Coated Slow Release Tablets

Tablets containing sodium salicylate were prepared by direct compression and coated with ethylcellulose and polyethylene glycol 3350. The effect of drug loading, direct compression carrier type, polymer ratio in the coating solution, pH of the dissolution medium, and agitation speed on the drug release were investigated using the USP XXI paddle method. It was observed that direct compression carriers, ratio of ethyl cellulose to polyethylene glycol, the amount of drug present in the tablet, and agitation speed used did not have any influence on the drug release from coated tablets, while the pH of the dissolution medium (gastric vs. intestinal fluids) was found to affect the drug release.