The Use of Isothermal Solution Calorimetry as a Promising Technique to Monitor Drug Release Kinetics
Eunice F S Vieira, Ângelo Augusto Araújo
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.
