EFFET OF COMBINATION OF HPMC AND CARBOPOL 934P ON THE PROPERTIES OF THE GASTRIC FLOATING TABETS OF TIMOLOL MALEATE

Abstract

The purpose of the present research wasto evaluate the effect of carbopol 934P on gastroretentive drug delivery system.Floating tablet containing timolol maleate were prepared by direct compressionmethod, using three grades of polymer HPMC [K15M, K4M, K100M] and carbopol934P. Sodium bicarbonate and citric acid was incorporated as a gas-generatingagent. The floating tablets were evaluated on the basis of pre-compression andpost-compression characteristics. The pre-compression characteristics such asangle of repose, bulk density, tapered density and compressibility index showedsatisfactory results for all the nine formulations. The results ofpost-compression such as weight variation, hardness, friability and drugcontent estimation showed that all the nine formulations complied with theofficial requirement of IP. The buoyancy lag time indicated that theformulation F1, F4 and F7 without carbopol 934P were less than 8 sec, where asformulation containing carbopol 934P had greater lag time. Formulationcontaining only HPMC grade polymers floated less than 8 h as compared to the formulationcontaining HPMC with carbopol 934P floated more than 12 h. The in vitro dissolution studies indicated94.2% drug release in 12 h by the formulations F2, F3, F5, F6, F8 and F9containing different concentration of carbopol 934P with different grades ofHPMC, when compared to 100% drug release within 9 h by the formulation F1, F4and F7 containing only different grades of HPMC polymers. All formulationfollowed the Higuchi release model. The drug release from the tablets wassufficiently sustained and non-Fickian transport of the drug from tablets wasconfirmed. Hence it can be inferred that the inclusion of carbopol 934P canresult in sustained drug delivery over 12 h, enhances the gastric floating timeand also increases buoyancy lag time. KEYWORDS:Timololmaleate, HPMC, carbopol 934P, Floating tablets, direct compression