MECHANISMS OF TIMOLOL RELEASE FROM MONOISOPROPYL PVM-MA MATRICES WITH AND WITHOUT A BASIC SALT

Alkyl monoesters of poly(vinyl methyl ether-maleic anhydride) (PVM-MA) are bioerodible materials that can be used to control drug release, pH-dependent drug release from these polymers can be further modified with incorporated basic salts. This study shows that depending on mixing polymer erosion and drug release may be controlled either by polymer ionization or by hydrogen ion transport across the static diffusion layer. Timolol is released at a constant rate from the matrices with sodium acetate and, thus, they are preferred to those containing disodium phosphate.