Hydroxypropylmethylcellulose sustained release technology

Abstract

The use of polymers in controlling the release of drugs has become important in the formulation of pharmaceuticals. Watersoluble polymers such as polyethylene glycol and polyvinylpyrrolidone may be used to increase the dissolution rates of poorly soluble drugs (Ford)1 and slowly soluble, biodegradable polymers such as polylactic acid may be used for controlled release implants (Rak et a1.2), Hydrogels provide the basis for implantation, transdermal and oral-controlled release systems. Hydroxypropylmethylcellulose (HPMC) are cellulose ethers which may be used as the basic for hydrophilic matrices for controlled release oral delivery. In tablet matrix systems the tablet is in the form of compressed compact containing an active ingredient, lubricant, excipient, filler or binder. The matrix may be tabletted from wet-massed granules or by direct compression. This review article examines a previously published series of work and concentrates on the following aspects of the subject; the relationship between release rate and quantity of polymers, such consideration allow a certain predicability in release rates to be made. Also the effect of drug particle size, tablet shape and the presence of additional diluents in the formula are examined.