Effects of acrylic acid polymer and its arrangement on drug release from a wax matrix.

The release of phenacetin from a wax matrix was improved by the addition of an acrylic acid polymer. Increasing the amount of polymer increased the release rate of phenacetin due to the formation of pores and channels in the matrix resulting from leaching of the polymer. The leaching was affected by the pH of the dissolution medium as well as by the methods used to prepare the granules. The polymer in ordered powder mixes behaved differently from that uniformly dispersed in a wax matrix. The drug appeared to be released by an approximate zero-order process at pH 7.5 from tablets containing the polymer.