Formulation, in vitro and ex vivo characterization of mucoadhesive buccal tablets for antihypertensive drug

Abstract

Objective: Olmesartan belongs to a class of angiotensin II receptor blockers. It is used in the treatment of hypertension. However, it undergoes extensive hepatic first-pass metabolism, resulting in low oral bioavailability is about 26%. The aim of this study was to prepare and evaluate the mucoadhesive buccal tablets of olmesartan with a goal to increase the bioavailability and improve the patient compliance. Methods: Mucoadhesive buccal tablets were prepared by a direct compression technique using mucoadhesive polymers such as hydroxypropyl methylcellulose (HPMC K4M), sodium carboxymethylcellulose (SCMC), and Carbopol 934P. The tablets were evaluated for weight variation, thickness, hardness, friability, surface pH, swelling index, drug content uniformity, in vitro drug release, ex vivo mucoadhesive strength, ex vivo mucoadhesive time, and ex vivo permeation studies. The release kinetics was calculated to determine the drug release mechanism. Results: The physicochemical properties of all the formulations were shown to be within the limits. The optimized buccal tablets F2, F7, and F11 showed satisfactory drug release rates with the diffusion controlled mechanism. Optimized buccal tablets developed for olmesartan possess reasonable mucoadhesive strength, mucoadhesive time, and surface pH was in an acceptable salivary pH 6.76±0.28–6.89±0.34. The ex vivo permeation studies for optimized tablets were shown satisfactory drug permeation and could meet the target flux 0.991 mg h−1cm−2. Conclusion: The obtained results could be used as a platform to develop the buccal delivery of this drug, which bypasses the first-pass metabolism and results in the improvement of bioavailability. Hence, the present study concludes that the olmesartan could be delivered through the buccal route.