Uniformity and physical states of troglitazone in solid dispersions determined by electron probe microanalysis and...

Solid dispersions of troglitazone with PVP K30 in a weight ratio of 1:2 were prepared by the closed melting method. Solid dispersions that exhibit different degrees of crystallinity (0 and 36%) were prepared by changing the charged amount of water, which functions as a plasticizer for PVP K30. Electron probe microanalysis (EPMA) and microthermal analysis (micro TA) of the solid dispersions were performed to investigate the uniformity and physical state of troglitazone in the solid dispersions. The EPMA study confirmed that troglitazone was dispersed homogeneously in the sample whose apparent crystallinity was 0%. However, the sample with a 36% crystallinity was heterogeneous. The micro TA study showed that the sample with a 36% crystallinity was present in two states, crystal and amorphous. EPMA and micro TA would be useful tools to confirm the uniformity and physical states, respectively, of solid dispersions.