The Use of Isothermal Solution Calorimetry as a Promising Technique to Monitor Drug Release Kinetics

Abstract

The objective of the present article is to emphasize that isothermal solution calorimetry (ISC) can be used to determine kinetics of reactions of interest in biotechnology. The major advantage of this technique is that it enables to characterize drug release profiles in real time noninvasively. Here ISC was used to monitor pyrimethamine release incorporated in hydrogels of oxidized alginate, ADA, and oxidized alginate blended with chitosan, ADA-Chit. The mechanism of pyrimethamine release was analysed using the semi-empirical equation so-called power law. From plots of cumulative heats concerning drug release, Qrel(t), versus time, values of apparent rate release, k, and diffusion exponent, n, were determined. The values of n were found to be 1.22 for ADA and 1.09 for ADA-Chit, indicating that the drug release is controlled by polymer relaxation.