Effect of Particle Size and Polymer Loading on Dissolution Behavior of Amorphous Griseofulvin Powder.

The effect of particle size on the dissolution behavior of the particles of amorphous solid dispersions (ASDs) of griseofulvin (GF), with 0%-50% Kollidon VA 64 as a crystallization inhibitor is investigated. Both the final dissolved GF concentration and the dissolution rate of GF ASDs were found to be inversely proportional to the particle size. The solution concentrations for the smallest (45-75 μm) size group with different polymer loadings were significantly higher than those for the largest (250-355 μm) group regardless of the initial GF amount. Specifically, the dissolution rate of GF ASDs with 50% polymer loading for the finest group was 2.7 times higher than for the largest group under supersaturating conditions. The rates of dissolution and recrystallization were assessed through surface concentration (C) and Avrami recrystallization rate kinetics, where the solid-state recrystallization was confirmed using Raman spectroscopy. Outcomes indicated that particle size reduction enhanced ASD drug loading by reducing the amount of polymer necessary as finest size ASDs initially dissolve faster, negating their higher recrystallization rate. Kollidon® VA 64 at 30% loading was sufficient to inhibit the GF recrystallization. Overall, the combination of particle size reduction and recrystallization inhibition is effective for improved dissolution behavior of GF ASDs.