Polymer matrix diffusion-controlled drug delivery systems

Polymer matrix diffusion-controlled drug delivery systems. 

Polymer Matrix Diffusion-Controlled Drug Delivery Systems... 

Details are given of pilocarpine trapped in a matrix diffusion-controlled drug delivery system using hydrophilic inserts of polyhydroxyethyl methacrylate. The physical and chemical properties of pilocarpine were investigated to determine the mechanism of drug-polymer interaction and the effect of drug release behaviour of controlled release polymeric devices. 22 refs. 

Fig. 13 The controlled release of drug molecules from a (membrane-matrix) hybrid-type drug delivery system in which solid drug is homogeneously dispersed in a polymer matrix, which is then encapsulated inside a polymeric membrane, where D, P, and h are the diffusivity, permeability, and thickness, respectively, and the subscripts p, m, and d denote the drug depletion zone in the polymer matrix, polymer coating membrane, and diffusion layer, respectively.

Polymers and biopolymers have been used in medicine for centuries. These important materials partly have their own therapeutic effect (active substances), and partly ensure the formulation, stability, and applicability of the dosage form (additives). The discovery of controlled drug delivery systems was a major result of research-development in pharmaceutical technology. In these so-called therapeutic systems, polymers ensuring a predetermined rate of membrane or matrix diffusion are used. Mucoadhesion (adhesion to biological surfaces) and the group of stimuli sensitive (environment sensitive) polymers play an important role in controlling the therapeutic effect. 

To overcome the problem, they used controlled drug-delivery systems. With this we can deliver drugs in a constant, predetermined rate to the repair area only. The active molecule can be encapsulated with the polymer member and there can be slow release of the drug into the tissues. In few cases, the release of the molecule may be due to the diffusion of the pol mier matrix. PolyQactic acid) and polyfortho ester)s are degradable pol miers that are used for drug-delivery systems. 

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