Studies On Monolithic Core Osmotic Pump Tablets Of Prazosin Hydrochloride And Oleanolic Acid

In recent years, more attention has been focused on the development of novel drug delivery systems, and the osmotic pump tablet holds a prominent place in oral controlled release system. It is easy to prepare osmotic pump tablet for water-soluble drugs but difficult for water-insoluble drugs. Therefore, the preparation for water-insoluble drug monolithic osmotic pump tablet was studied in this paper. The studies involved the following aspects:(1) For avoiding the drill process in the preparation of the osmotic pump tablet, the core tablet with an indentation was compressed by the punch with a needle, and then osmotic tablet was prepared by coating the indented tablet. The delivery orifice is the uncoated part of the indentation. The laser drilling was exempted and the preparation of osmotic pump tablet was simplified.(2) Prazosin hydrochloride was selected as the model drug, sodium chloride as the osmotic agent and polyethylene oxide as the suspending agent. In order to find out the optimal core formulation, the uniform design was employed and a multiple regression equation was obtained with the experimental data of drug release rate, and then the formulation was optimized. The optimal osmotic pump tablet was found to be able to deliver prazosin hydrochloride at a rate of approximate zero-order up to 24 h. The stirring rates in the range of (50-100) r·min^-1.and the release media had no significant influence on drug release profile. The study demonstrated that it was a feasible method to prepare a monolithic core osmotic pump tablet by compressing a core tablet with an indentation and subsequently coating. The orifice size of the core tablet hardly affected drug release in the range of (0.80¹.15) mm.(3) The solid dispersion systems of oleanolic acid (OA) with various carriers such as polyethylene glycol (Mr:4000 g/mol) and polyvinylpyrrolidone (PVPoo, PVPk9o ) were prepared and applied in OA osmotic pump tablet. It was found that the solid dispersion prepared by OA with PVPjgo showed the best performance in the drug release from OA osmotic pump tablet. The stirring rates in the range of (75-125) r-min"1 and the release media had no significant influence on the release profiles of the OA monolithic osmotic pump tablet.