Comparative in vitro dissolution study of carbamazepine immediate-release products using the USP paddles method and the flow-through cell system

Dissolution profiles of four carbamazepine immediate-release generic products (200 mg tablets) and the reference product Tegretol® were evaluated using the USP paddles method and an alternative method with the flow-through cell system, USP Apparatus 4. Under official conditions all products met the Q specification, dissolution profiles of generic products were similar to the dissolution profile of the reference product (f2 > 50) and model-independent parameters showed non significant differences to the reference product except mean dissolution time for product A (p < 0.05). On the other hand, when the flow-through cell system was used, none of the products met the pharmacopeial specification at 15 min and product A did not reach dissolution criteria at 60 min, dissolution profiles of all generic products were not similar to the reference product profile (f2 < 50) and all model-independent parameters showed significant differences compared to the reference product (p < 0.05). Weibull’s model was more useful for adjusting the dissolution data of all products in both USP apparatuses and Td values showed significant differences compared to the reference product (p < 0.05) when USP Apparatus 4 was used. These results indicate that the proposed method, using the flow-through cell system, is more discriminative in evaluating both, rate and extent of carbamazepine dissolution process from immediate-release generic products.