Solid lipid nanoparticles (SLN) for controlled drug delivery. I. Production, characterization and sterilization

Solid lipid nanoparticles (SLN) were produced by high pressure homogenization of a melted lipid (Dynasan 112) dispersed in water at increased temperature (70°C). Soy lecithin and poloxamer 188 were used as surfactants and stabilizers of the particles. The effect of homogenization parameters (pressure, cycle number) was studied and optimized to yield solid lipid nanoparticles of a quality suitable for intravenous injection. Particles were characterized by photon correlation spectroscopy (PCS) and zeta potential measurements, the fraction of large particles being the limiting factor for i.v. injection was determined using a Coulter Counter. The optimum formulation was suitable for i.v. injection (monograph ‘Particulate Matter’, USP XXII). SLN stabilized with soy lecithin could be sterilized by autoclaving.