Definition of a solvent system for spherical crystallization of salbutamol sulfate by quasi-emulsion solvent diffusion (QESD) method.

In this paper we describe how the spherical crystallization process by QESD method can be applied to a water‐soluble drug, salbutamol sulfate. The type of solvent, antisolvent, and emulsifier and the concentration of emulsifier to be used for the production of spherical particles with a size range 80–500 μm are determined. Furthermore, the solvent/antisolvent ratio and the temperature difference between them (ΔT) are studied. It was observed that, in the case of salbutamol sulfate, the ΔT value has no influence on the formation of spherical particles. A very large metastable zone of salbutamol sulfate in water could explain this phenomenon. Finally, the influence of emulsifier concentration and of maturation time on the size of spherical particles is studied. The results show that these two parameters must be fixed to control the size of the recovered particles. © 2001 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1620–1627, 2001