Enhanced dissolution of megestrol acetate microcrystals prepared by antisolvent precipitation process using hydrophilic additives

Microcrystals of megestrol acetate (MA), a poorly water-soluble drug, were successfully prepared using an antisolvent precipitation technique for improving the dissolution rate. The effective hydrophilic polymers and surfactants used were screened for their abilities to produce smaller particle sizes. Raw micronized MA and processed MA microcrystals were ranked by the Student-Newman-Keuls test in order of increasing particle size and SPAN values as follows: processed MA microcrystals in the presence of polymer and surfactant (mean diameter 1048. nm) <processed MA microcrystals in the presence of polymer (1654. nm) <processed MA microcrystals in the absence of polymer and surfactant (3491 nm) <raw micronized MA (4352 nm). The order of BET surface area was reversely ranked. Processed MA microcrystals in the presence of polymer and surfactant slightly decreased crystallinity and altered crystal habit and preferred orientation without change in polymorph. In addition, the dissolution properties of the processed MA microcrystals in the presence of polymer and surfactant were significantly enhanced as compared to that of the raw micronized MA. This effect is mainly due to a reduction in particle size resulting in an increased surface area. Therefore, it was concluded that the antisolvent precipitation technique in mild conditions could be a simple and useful technique to prepare poorly water-soluble drug particles with reduction in particle size, a narrow particle size distribution and enhanced dissolution properties.