The preparation of pellets containing non-ionic surfactants by extrusion/spheronization.

The aim of the study was to investigate the possibility of incorporating non-ionic surfactants into pellets produced from microcrystalline cellulose by the process of extrusion/spheronization and the properties of the pellets. A hydrophilic surfactant, polysorbate 60 (PS 60), and two hydrophobic surfactants, sorbitan monostearate (S 60) and sorbitan monooleate (S 80), were included in the water used to form the pellets in concentrations ranging from 5 to 95%. The presence of the surfactants influenced the type of the extrusion profile and improved the ability to provide round pellets, and the addition of the surfactants changed the range of liquid levels required to prepare the pellets. At a low level, i.e., 5%, all the surfactants increased the range of water contents possible, compared to the use of water alone. At high surfactant levels, the level of liquid, which could be used, became restricted. The median size of the pellets was dependent on the type of surfactant and the concentration included in the formulation. The range of sizes produced was generally quite narrow and there were many systems with more than 90% of the pellets in the modal fraction. The highest concentration of the surfactant in water that can be used to form pellets ranged from 50% for S 60, to 80% for S 80 and 95% for PS 60. The maximum amount of the surfactant, which could be incorporated into the final pellet, however, was found to be approximately 22.5% for both the hydrophobic surfactants and 32.5% for the hydrophilic surfactant.