Biodegradable Hydroxylated Polymers as Controlled Release Agents

摘要

The use of the biodegradable poly(alkylene tartrates) and their polyurethane derivatives as potential controlled release matrices for drugs and other chemical substances is currently under investigation. A correlation between the rates of hydrolysis and swelling and the rates of methylene blue release from three hydroxylated polymers was demonstrated. The rate of release was found to vary with the degree of hydrophobicity of the polymer. Release rates from the more hydrophobic poly(decamethylene tartrate) tablets were lower than release rates from either the poly(octamethylene tartrate) or the poly(butamethylene:octamethylene tartrate) tablets. In all cases the rate of release was found to have a square root of time dependence as would be expected based on Fick's Law of Diffusion. In addition, when the tablet thickness was varied, the results were as expected if Fick's Law was valid. At high loading doses of methylene blue however. Fick's law was found to be no longer valid. Higher than expected concentrations of methylene blue were released. It was observed that both the rate of water uptake and the rate of hydrolysis had a square root of time dependence. The data suggest that the release of methylene blue from the polymer matrices involves more than simple Fickian diffusion. In fact, it is likely that release involves a complex interplay of hydrolysis, water uptake, and diffusion. Reprints. (aw)