Dissolution of Different Commercial Aspirin Tablets Using a Novel Off-Center Paddle Impeller (OPI) Dissolution Testing System

Dissolution testing is routinely conducted in the pharmaceutical industry to provide in vitro drug release information for quality control purposes. The most common dissolution testing system for solid dosage forms is the United States Pharmacopeia (USP) Dissolution Testing Apparatus 2.  In this work , a modified Apparatus 2 , termed “OPI” System for “off-center paddle impeller ,” in which the impeller was placed 8 mm off center in the vessel was tested to determine its sensitivity to differentiate between the dissolution profiles of differently formulated and manufactured tablets.  Dissolution tests were conducted with both the OPI System and the Standard System using three different brands of aspirin at nine different tablet positions.  The OPI system produced dissolution profiles that were highly dependent on the different brands of aspirin used , similarly to those generated in the Standard System.  However , the dissolution profiles obtained with the OPI apparatus were found to be largely independent of the tablet location at the vessel bottom , whereas those obtained in the Standard System generated statistically different profiles depending on tablet location.  It can be concluded that the newly proposed OPI system can effectively eliminate artifacts generated by random settling of the tablet at the vessel bottom , thus making the test more robust , while at the same time being just as sensitive as the Standard System to actual differences in differently manufactured tablets having intrinsically different dissolution profiles.