In vitro properties of surface-modified solid lipid microspheres containing an antimalarial drug: halofantrine.

To formulate and evaluate in vitro, surface-modified solid lipid microspheres containing halofantrine using lipid matrix formed from goat fat and a phospholipid (P90H). The model drug, halofantrine in an increasing concentration of 1%, 2%, 3%, 4% and 5% w/w was incorporated into surface-modified solid lipid microspheres formulated by hot homogenization. Effect of drug concentration on the encapsulation efficiency was studied. The dispersion was evaluated using particle size, particle morphology, pH and encapsulation efficiency. The drug formulation with highest encapsulation efficiency was selected and used for the release studies and compared with the release from a commercial dosage form (Halfan® 250 mg tablet, Glaxo-Smithkline, Mayenne France) using simulated gastric fluid (SGF pH 1.2), simulated intestinal fluid (SIF pH 7.2) and phosphate buffer (pH 6.8) as biorelevant media. Results were analyzed statistically and the level of significance was taken to be P < 0.05). Discrete and spherical solid lipid microspheres were produced. The particle size of the dispersion was low (32.48-33.87 μm) with minimal particle growth and high encapsulation efficiencies (86.8%-91.0%) after 3 months. The pH of the microspheres dispersion changed appreciably after 3 months. In vitro release result obtained revealed sustained and controlled drug release from the lipid microspheres compared with the tablet dosage form. Formulation of halofantrine as solid lipid microspheres presents a better alternative to the conventional tablet formulation as the in vitro dissolution of the highly lipophilic halofantrine was highly improved.