Comparative Dissolution of Diltiazem Immediate and Extended Release Products Using Conventional USP and Innovative Dissolution Paddles

Drug dissolution studies are commonly conducted using compendial methods employing USP Paddle and Basket apparatuses. In many cases, dissolution studies can be of limited benefit especially for product-dependent dissolution procedures like in extended release (ER) formulations. The high variability in dissolution testing, that is not productrelated, emphasizes the need for developing new methods for dissolution testing that can address the artifacts found with the current USP dissolution methods. A crescent shaped spindle was suggested as a solution to overcome drawbacks associated with conventional dissolution methods. Diltiazem immediateand extended-release tablets and capsules were used to evaluate the crescent-shaped spindle and compare it to the USP paddle system. Appropriate dissolution rates were obtained using crescent-shaped spindle at 25 rpm compared to higher rotation speeds of 75/100 rpm with the USP Paddle. Similarity factor (F2) and dissolution efficiency (DE) parameters were used to evaluate dissolution profiles. Statistical analysis using student t-test and P-value was used to compare the results under various test conditions. For the immediate release (IR) products, only one product out of four had similar dissolution profile in the USP paddle and Crescent shaped spindles. Two products out of five ER products were found similar based on the F2 value. In general, Crescent shaped spindle provided better evaluation for the dissolution of IR and ER products without any evidence of harsh stirring environment or crushing.