THE INFLUENCE OF EXCIPIENT PARTICLE-SIZE, SOLUBILITY AND ACID STRENGTH ON THE DISSOLUTION OF AN ACIDIC DRUG FROM 2-COMPONENT COMPACTS

The dissolution properties of mixed compressed discs containing ibupro fen and one of three different acid excipients were investigated and t he effect of various processing variables examined. Ibuprofen dissolut ion rate was shown to change depending on the acid excipient particle size used, the solubility of the excipient and its acid strength. Decr easing the excipient particle size resulted in a lowering of the ibupr ofen dissolution rate. A decrease of an order of magnitude up to 20-fo ld could be achieved when smaller sized excipient particles were used. The observed dissolution phenomena associated with changing excipient particle size were explained in terms of percolation theory and disso lution from pores of a dimension similar to or larger than that of the aqueous boundary layer. It was also observed that the stronger the ac id used as the excipient and the greater its solubility, the greater w as its suppressing effect on the dissolution rate of the drug.