Wettability study of clofazimine and poly(vinyl methyl ether/maleic anhydride) copolymer coevaporates

Abstract

Solid coevaporates of the antileprotic drug, clofazimine, with a poly(vinyl methyl ether/maleic anhydride) copolymer (PVM/MA, Mol Wt 20 000) were prepared by the solvent evaporation method. TThe drug/polymer carrier weight ratios in the coevaporates examined were 1:5, 1:10 and 1:20. The effect of the hydrophilic PVM/MA copolymer on the surface characteristics of the hydrophobic rug clofazimine was studied by performing contact angle measurements on tablets compressed from powders of both the pure components (drug and carrier) and their coevaporates. Contact angles, τ, of sessile drops of both distilled water and acidic, neutral and alkaline aqueous solution, previously used as dissolution media for the coevaporates, were determined at 37°C. It was found that τ decreased (i.e the wettability of the coevaporates increased) with increasing PVM/MA copolymer content. The increasing wettability of the coevaporates is consistent with the results obtained on dissolution for the relevant powder samples. © 1992.