Development of ritonavir solid lipid nanoparticles by Box Behnken design for intestinal lymphatic targeting

The aim of the present study was to develop and evaluate solid lipid nanoparticles (SLNs) of anti-HIV drug ritonavir to target intestinal lymphatic vessels and bioavailability enhancement by the oral route of administration. SLNs were prepared by solvent evaporation followed by ultrasonication using Compritol 888 and sodium lauryl sulfate using Box Behnken design. SLNs were characterized for particle size, zeta potential, entrapment efficiency, in vitro release and pharmacokinetic studies. The average particle size for the optimized formulations was well within 300 nm, and PDI (0.361) and zeta potential (−32.4 mV) were also found to be in acceptable ranges. The encapsulation efficiency ranged from 53.20 ± 4.13 to 73.04 ± 2.85%. Scanning electron microscopy images indicated the complete dispersion of drug within the lipid structure. The less intense peaks at 2θ of 21.03° and 18.86° were observed in the XRD diffraction spectrum of SLNs indicating transformation into an amorphous form. The pharmacokinetic studies indicated that the extent of absorption for the solid lipid nanoparticles was found to be much higher in the spleen and thymus compared to that in the plasma which indicated that the developed formulations could enhance the bioavailability and intestinal lymphatic target specificity.