Controlled release of levamisole from poly-(epsilon-caprolactone) matrices .1. Effects of the nature and the concentration of the drug incorporated into the matrices

Vandamme, T;Mukendi, JFN
(1996) European Journal of Pharmaceutics and Biopharmaceutics — Vol. 42, n° 2, p. 116-123 (1996)

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  • Vandamme, T
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  • Mukendi, JFN
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Abstract
Oral sustained release matrix systems for cattle (rumino-reticulum devices) were developed. The influence of the nature of the anthelmintic agent, levamisole under the lipophilic form (base) and the water-soluble form (hydrochloride) was evaluated in order to choose the appropriate candidate for the release kinetics. Three levels (20, 30 and 40%) for the levamisole base and seven levels (20, 30, 40, 50, 60, 70, 80%) for the levamisole hydrochloride were used to study the influence of the concentration on the release of the anthelmintic drug from the biodegradable matrix, consisting of poly-(epsilon-caprolactone). The dissolution rate of the drug was determined in a medium with an pH and a ionic strength as close as possible to those encountered in the ruminal fluids. For the cylindrical matrices containing the water-soluble form of the anthelmintic agent, the release rate increased when larger amounts of drug were incorporated into the matrix. At same concentrations, this effect was less pronounced for the lipophilic form of levamisole than with levamisole hydrochloride, This suggests that the mechanism of the release was different for the two forms of the drug. In order to explain this release mechanism, scanning electron microscopy (SEM) and polarized light microscopy were used. With these techniques, it was observed that the levamisole hydrochloride was completely insoluble in the poly-(epsilon-caprolactone) matrices. Conversely, the levamisole base was soluble in the polymer phase up to 10% and the polymer was soluble in the levamisole base up to 10%. Correlation of the dissolution results with physico-chemical properties of the drugs indicated that the release of the lipophilic form of the drug was associated with the reciprocal solubility of the drug and the polymer.
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Vandamme, T., & Mukendi, J. (1996). Controlled release of levamisole from poly-(epsilon-caprolactone) matrices .1. Effects of the nature and the concentration of the drug incorporated into the matrices. European Journal of Pharmaceutics and Biopharmaceutics, 42(2), 116-123. https://hdl.handle.net/2078.5/144030 (Original work published 1996)