Development of Simple Dissolution Methods for Felodipine and Combined Amlodipine Besylate-Indapamide Extended Release Tablets without Stationary (Felodipine) Basket

Background: The dissolution method for certain drugs needs specialized conditions. Dissolution testing for felodipine extended release (ER) tablets (Plendil® 5 mg) and amlodipine-indapamide fixed dose (Natrilam®, 5/1.5 mg) ER tablets requires the use of a stationary (felodipine) basket in USP Apparatus II. Objective: The study aimed to develop simple methods for Plendil® and Natrilam® without the use of a felodipine basket. Methods: The dissolution profiles obtained from different media and paddle speeds were used to compute miscellaneous dissolution parameters and were compared to those obtained from standard (existing) methods using a felodipine basket. Results: The f1, f2, and bootstrap f2 (5th % percentile) values for Plendil® 2.47, 88.17, and 54.62, respectively, and all other dissolution factors revealed similarity between standard and the selected test method with 1% Tween 20 at 50 rpm. For Natrilam®, f1 and f2 and bootstrap f2 5.13, 72.92, and 62.67, respectively, and all other dissolution parameters showed similarity of the standard and selected test method using 0.1N HCl media having 0.38 gm/L EDTA with a sinker at 100 rpm. Release of products assumed zero-order and Weibull model, respectively. Conclusion: Test dissolution methods for Plendil® and Natrilam® tablets produced equivalent dissolution profiles compared to their respective standard methods with stationary basket USP Apparatus II.