Droplet Formation by Oozing a Solution from Silicone Rubber for the Preparation of Drug Particles with a Narrow Size Distribution

Polymeric solid materials can ooze liquid. Although this can be a disadvantage in some environments, in this study, we use this oozing property to prepare drug particles with a narrow size distribution, which is a critical property of pharmaceuticals that can determine their bioavailability. Silicone rubber was first soaked in a mixed dimethyl sulfoxide/<i>n</i>-propyl acetate solvent containing the target drug. By drying the rubber under conditions that allowed only the <i>n</i>-propyl acetate to evaporate, droplets of dimethyl sulfoxide containing the drug were formed on the surface. The droplet size distribution was improved by allowing the droplets to fuse. Solute particles, such as mesalazine obtained by drying the droplets, showed a narrow size distribution, reflecting the uniformity of the droplets. This particle preparation method is cost-effective and easy to scale up.