Solid Lipid Nanoparticles of Atovaquone Based on 24 Full-factorial Design

Solid lipid nanoparticles of atovaquone (ATQ-SLN) were prepared by high shearhomogenization method using tripalmitin, trilaurin, and Compritol 888 ATO as the lipidmatrices and Phospholipon 90H, Tween 80, and poloxamer 188 as the surfactants. Optimizationof the formulations was conducted using 6 sets of 24 full-factorial design based on fourindependent variables that were the number of homogenizing cycles, concentration of the lipid,concentration of the co-surfactant, and concentration of the main surfactant. The dependentvariables were particle size and polydispersity index (PdI). The homogenizing cycles showed anegative influence on the dependent variables which reduced both the particle size and the PdIvalue. Moreover, a combination of certain percentages of the main surfactant and co-surfactantalso showed a negative influence that reduced both the particle size and PdI value. Selectedformulations from each design were further characterized for the entrapment efficiency andyield. The optimised formulation of ATQ-SLN consisted of trilaurin, Phospholipon 90H andTween 80 with a particle size of 89.4 ± 0.2 nm and entrapment efficiency of 83.0 ± 1.7%. Thein-vitro release evaluation of the formulation showed a complete and immediate release of ATQfrom the SLN that could be a solution to improve the poor aqueous solubility and hence poorbioavailability of the drug.