UNIFORM AND IMPROVED BIOAVAILABILITY OF NEWLY DEVELOPED RAPID AND SUSTAINED-RELEASE SUSPENSIONS OF IBUPROFEN MICROSPHERES

New rapid and sustained release suspensions of ibuprofen microspheres were investigated in in vitro release and in vivo drug absorption studies. The drug release rate from the suspensions was controlled by the particle size, drug-polymer ratio and internal porosity of microspheres. The rapid release suspension resulted in significantly low intersubject variation in bioavailability, demonstrating the same rate and extent of drug absorption as the conventional marketed ibuprofen granule. Out of three suspensions studied, the sustained release suspension (suspension 3) showed ideal bioavailability: an equal extent of absorption (AUC) and a 3-fold longer time of peak plasma level (T(max)) as compared with the marketed conventional granule. More interestingly, although the drug release rates from two suspensions (suspensions 2 and 3) were identical, there were significant differences in the rate and extent of bioavailability between them. Moment analysis suggested that these differences in bioavailability could be attributed to the GI residence time of microspheres.