Extended release lipophilic indomethacin microspheres: Formulation factors and mathematical equations fitted drug release rates

PubMed ID: 12791411Extended release liphophilic microspheres of indomethacin were prepared using cetostearyl alcohol (CsA), stearyl alcohol (SA) and cetyl alcohol (CA) in the various drug-lipid ratios. The release of indometacin was studied on the basis of USP criteria and the effects of drug-lipid ratio, the size of microspheres and carboxymethylcellulose sodium (CMC-Na) added as a hydrophilic polymer on the drug release were investigated. In vitro dissolution studies were performed using USP XXIII apparatus I at pH 6.2. Release profiles were evaluated according to first order, Higuchi square root of time and Hixson-Crowell cube root models. The best fit was found with the square root of time model (r2=0.991) for the microspheres (125-250 µm) prepared in 1:4:1 drug-lipid-copolymer ratio using stearyl alcohol. With a further regression analysis, an excellent equation (Release%=-10.721+42.549* ?t-4.027*t) was developed for empirical drug estimation (r2=0.998). © 2003 Elsevier Science B.V. All rights reserved