Effect of Viscosity Imparting Agents on In vitro Drug Release from PEG Based Suppositories

Acetaminophen loaded suppositories were prepared and the effects of viscosity imparting agents on drug release were investigated. Suppositories containing 125 mg of acetaminophen were prepared by fusion method using PEG 4000 and PEG 1500 as hydrophilic base. In vitro dissolution studies were carried out by a thermal shaker with a shaking speed of 90 rpm at a temperature of 37 ± 0.50C in phosphate buffer of pH 6.8. The effect of viscosity imparting agents on the drug release into phosphate buffer were investigated by adding 0.1, 0.2 and 0.3% Xanthan gum, sodium carboxy methyl cellulose, acacia, hydroxyl propyl methyl cellulose 15 cps and 50 cps. The In vitro release data showed that drug release was linear in phosphate buffer. After incorporation of viscosity imparting agents in phosphate buffer a biphasic drug release profile i.e. initial lag phase followed by linear phase was observed. Lag time depends on nature and concentration of viscosity imparting agents. It is evident from the result that lag time increases with the increase in percentage of viscosity imparting agent. There is less or no effect of change of concentration of acacia on the lag time. After lag time drug release from the suppositories showed a linear fashion. It was found that the release rate decreases when dissolution medium contains high percentage of Xanthan gum and also sodium carboxy methyl cellulose. However in case of incorporation of HPMC into the dissolution medium, release rate decreased up to 0.2% HPMC, but with 0.3% HPMC the release rate increased. Inclusion of different percentage of acacia into the dissolution medium has not significantly changed the release of acetaminophen from suppositories. Key words: Suppositories, Acetaminophen, Viscosity imparting agent Dhaka Univ. J. Pharm. Sci. Vol.4(1) 2005 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website