Thermoanalytical measurements conducted on repaglinide to estimate the kinetic triplet followed by compatibility studies between the antidiabetic agent and various excipients

Repaglinide is an antidiabetic agent that is used in the treatment of the type II diabetes mellitus. In this study, we aimed to determine the thermal behavior of this pharmaceutical agent, as well as the kinetic parameters that characterize the main degradation process of repaglinide. We also targeted a study in which the compatibility of repaglinide with various excipients was evaluated by thermoanalytical and spectrometric techniques. In order to determine the kinetic triplet of the degradation process, the repaglinide was submitted to a controlled degradation process under a temperature program from 40 to 500 °C in air flow of 100 mL min−1 and according to ICTAC 2000 Protocol, samples were heated at five different heating rates: β = 5, 7, 10, 12 and 15 °C min−1, respectively. All data were computed by four isoconversional kinetic methods: FR, FWO, KAS and modified NPK. The compatibility studies implied preparing the binary mixtures of repaglinide and different excipients using a mass ratio of 1:1. For the thermoanalytical evaluation samples of the mixture were analyzed following a temperature program from 40 to 500 °C in air flow of 100 mL min−1 with a heating rate of 10 °C min−1. The spectrometric analysis was performed using the same type of mixtures. The studies show a good compatibility between repaglinide and the five excipients used and also well correlated values of the mean activation energy obtained by FWO, KAS and modified NPK methods.