The choice of lipids and surfactants for injectable extravenous microspheres

Suspensions of lipid microspheres sizing from 1 to 30 microm, whose fluidity and lipid/surfactant composition is suitable for parenteral administration were developed. None of the formulations prepared with Precirol (palmitostearate), as the only lipid, was physically stable during storage, because liquid suspensions formed semisolid gels within one week. Stable 10% (w/w) suspensions of lipid microspheres were produced using saturated triglycerides in combination with medium chain unsaturated triglycerides (Miglyol) as lipids and polysorbate 80 (2% w/w) as a surfactant.