WETTABILITY OF DRUG LOADED POLYMER MATRICES

ABSTRACT

Drug release is to a large extent influenced by penetration of a dissolution liquid into a polymer matrix. If an aqueous medium does not wet a matrix, its penetration into the polymer bulk and the resulting drug extraction would be considerably hindered. It is therefore of extreme importance to study not only the physical state of drug loaded matrices but also their wettability and their penetration by an aqueous medium.

In the present review paper we describe the results of two investigations, performed in our laboratory and having direct relevance to the medical and pharmaceutical fields: the estimation of wettabilities of polymer tablet formulations and of drug loaded polymer films. For tablet formulations it was clearly demonstrated that the use of high-viscosity polyols for contact angle and penetration experiments yielded incorruptible data which enabled to determine mean pore size of tablets from the Washburn equation. For drug-loaded cast films, as exemplified for SIBA (a cytostatic drug)-loaded ethylcellulose cast films, the choice of the solvent appeared to play a determinant role on the wettability and heterogeneity of films.