Formulation and in vitro evaluation of ibuprofen-Carbopol 974P-NF controlled release matrix tablets. III: Influence of co-excipients on release rate of the drug.

In order to assess the potential of carbopol 974P-NF as matrix material in hydrophilic matrix tablets containing a slightly water-soluble drug, ibuprofen (IBF), controlled release matrix tablets of ibuprofen and carbopol 974P-NF, at different drug to polymer ratios, were prepared by the direct compression method. The influence of the concentration of the matrix material (carbopol 974P) and several co-excipients (lactose, microcrystalline cellulose, and starch) on the release rate of the drug was investigated. An in vitro dissolution test in pH 7.2 phosphate buffer solution showed that drug release from all the formulations containing carbopol 974P was considerably prolonged in concentration-dependent manners. Increasing the amount of carbopol 974P in tablets resulted in a reduction in the drug release rate and a linearization of the drug release curve. When the influence of the co-excipients on the release of the drug was examined, all of the co-excipients used in this study enhanced the release rate of IBF. However, lactose demonstrated slower and more linear release behavior as compared in microcrystalline cellulose or starch. The dissolution T50 and T90 values for the three co-excipients were in the order of lactose > microcrystalline cellulose > starch.