Many new pharmaceuticals have low water solubility, hampering their pharmaceutical activity upon administering. One approach to increase solution concentrations during drug administration is to increase the surface-to-volume ratio by decreasing the crystal product size. Sub-micrometer-sized niflumic acid crystals were produced by electrospray crystallization. Electrospray crystallization uses a high potential difference to create a mist of ultrafine charged solution droplets. The subsequent total solvent evaporation and droplet disruption process lead to crystallization of sub-micrometer-sized crystals. For concentrations well below the solubility concentration while using small nozzle diameters, niflumic acid crystals with a size of 200-800 nm were produced. In the absence of excipients, for the sub-micrometer-sized niflumic acid no significantly different dissolution profile compared to the conventional one was measured. However, if excipients were added, the dissolution rate for the sub-micrometer-sized product increases substantially in stimulated gastric juice, while that of the conventional product increased slightly. Probably the excipients avoid the aggregation of the hydrophobic sub-micrometer particles in the low pH environment.
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