FORMULATION AND EVALUATION OF BILAYER FLOATING TABLETS OF BETAHISTINE HYDROCHLORIDE
Dheeraj Lonkar*1, Girijesh Kumar Pandey1, Amit Joshi1, B.K. Dubey1, Salaj Khare1, Prabhat Jain2
1Technocrats Institute of Technology-Pharmacy Education and Research, Bhopal (M.P.)
2Scan Research laboratories Bhopal (M.P.)
The objective of the present study was to develop bi-layer tablets of betahistine hydrochloride is an orally administered antihistaminic drug with short half-life, which is characterized by initial burst drug release in the stomach and complies with the release requirements of sustained-release products. But they take lag time to start the action. Hence a new approach is tried that gives one immediate release dose and a sustained release dose in single dosage form call bilayer tablets. Immediate release layer delivers the initial dose, it contains superdisintegrants which increase drug release rate whereas sustained release layer float due to gas generating agent and releases drug at sustained manner for prolonged period. A direct compression method was used to formulate 9 batches. Superdisintegrants like sodium croscarmellose, crospovidone was used for immediate release layer and HPMC K4 M, HPMC K 15 M, PVP K30 like polymers were used in floating layer.A simple visible spectrophotometric method was employed for the estimation of betahistine at 264 nm and Beerâ€™s law is obeyed in the concentration range of 5-25 Âµg/ml. Preformulation studies were carried out to optimize the ratios required for various grades of polymers. The prepared floating tablets were evaluated for hardness, weight variation, thickness, friability, drug content uniformity, buoyancy lag time, total floating time, water uptake (swelling index), and in vitro dissolution studies. Successful formulation was developed having floating lag time as low as 36 sec and drug release was sustained up to 12 hrs. A biphasic drug release can be obtained by using bilayer tabletting technology which involved compression of immediate and sustained release layer together. Bilayered floating tablets with release characteristics offer critical advantages such as, site specificity with improved absorption and efficacy. This technology can be inculcated to various medicaments which have stomach as the major site of absorption.
Keywords: Bilayer floating tablets, Betahistine, Biphasic drug release, HPMC K 15 M.
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