Controlled release of levamisole from poly-(epsilon-caprolactone) matrices .3. Effects of molecular weight and polymer coating on drug release
(1996) International Journal of Pharmaceutics — Vol. 145, n° 1-2, p. 77-86 (1996)
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- Rumino-reticulum devices (RRDs) (oral dosage forms allowing the release of a drug in the first part of the stomach of grazing animals during a prolonged time) in the form of cylindrical matrices were constructed to release orally anthelmintics in large animals during a period of 3-5 months. The aim of this study was to determine the influence of the molecular weight of the poly-(epsilon-caprolactone) (PCL) constituting the polymeric matrix and the influence of coatings on selected RRDs, The influence of the molecular weight and the coating on these RRDs were studied by the rate and the kinetic release of a model anthelmintic compound, levamisole hydrochloride. For the molecular weight, no significant differences (P > 0.05) were observed for matrix systems with a molecular weight of 101 100 or 147 000 Da. Conversely, a faster release (P < 0.05) was observed for a matrix with a molecular weight of 53 500 Da. Different kinetic release profiles of levamisole were achieved by application of coatings of poly-(epsilon-caprolactone), poly-(L-lactide) (PLA) and poly-(D,L-lactide-co-glycolide) (PLGA). While all coatings of PCL or PLGA reduced the release rate of the drug, only the coatings with PLA induced a lag time (similar to 15 days) before the release of the drug. The lag time encountered with PLA coatings was attributed to the crystallinity of the polymer. For the RRDs constructed with different molecular weights and those coated with PCL, fractional release as a function of time is shown to fit the Roseman-Higuchi model. Plots of (1 - F) ln(1 - F) + F are linear with time where F is the fraction of drug released at time t. In vitro drug release studies were conducted in conditions as near as possible to those encountered in vivo. Based on the typical pH encountered in vivo, complete release of the drug would ensure good bioavailability of the drug following oral administration. Copyright (C) 1996 Elsevier Science B.V.
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Vandamme, TF., & Mukendi, J. (1996). Controlled release of levamisole from poly-(epsilon-caprolactone) matrices .3. Effects of molecular weight and polymer coating on drug release. International Journal of Pharmaceutics, 145(1-2), 77-86. https://doi.org/10.1016/S0378-5173(96)04727-8 (Original work published 1996)