Encapsulation efficiency of solid lipid hybrid particles prepared using the PGSS technique and loaded with different polarity active agents

The manufacture of particulate hybrid carriers containing a glyceryl monostearate (Lumulse^® GMS-K), a waxy triglyceride (Cutina^® HR), silanized TiO₂ and different active agents (caffeine, glutathione or ketoprofen) was investigated with the aim of producing controlled drug delivery systems based on solid lipid particles. Particles were obtained using the supercritical PGSS^® (particles from gas saturated solutions) technique. Experiments were performed at 13 MPa and 345 K, according to previous measurements of lipid melting points. Solid lipid particles were loaded with silanized TiO₂ and caffeine, glutathione or ketoprofen in percentages of 6-7 wt% for the mineral filler and 4.2, 5.6 and 16.1 wt% for the respective drugs. The particles obtained were analyzed in the solid state by thermogravimetric and X-ray diffraction analysis and scanning electron microscopy. Drug contents in the precipitated lipid samples and their elution profiles were studied by HPLC. Hydrophobic drugs, such as ketoprofen, were more efficiently encapsulated in the lipophilic lipidic matrix than hydrophilic drugs, such as caffeine and glutathione.