The objective of this study was to compare between the in traditional in vitrotesting and dissolution kinetics of selected commercial brands of ibuprofen and paracetamol tablets. Ibuprofen (400 mg/Tab) and paracetamol tablets (500 mg/Tab) from the Gulf Cooperation Council (GCC) pharmaceutical market were evaluated for hardness, friability, uniformity of weight, disintegration and dissolution profiles. The study indicated that there is a correlation between the different in vitro tests proposing that tablets with higher hardness value, slow disintegration time will show slower dissolution rate. The results indicated a significance difference between different brands in hardness, disintegration time and dissolution. This difference was more prominent for ibuprofen brands compared to paracetamol brands. The similarity test supported this findings where f2 for all comparisons for the ibuprofen tablets were less than 50. Dissolution kinetics indicated that the first order equation was best equation to give the goodness of fit and therefore to represent the dissolution data. The dissolution kinetics confirmed the difference between different brands of both ibuprofen and paracetamol tablets. The use of dissolution kinetics proved to be a good tool in studying the interchangeability of generic drugs. The study raise a valuable question about the interchangeability of different brands as this in vitro difference may suggest a more serious in vivo difference in their bioavailability.
