Injectable actarit-loaded solid lipid nanoparticles as passive targeting therapeutic agents for rheumatoid arthritis

This work systematically studied the intravenous injection formulation of solid lipid nanoparticles (SLNs) loaded with actarit, a poor water soluble anti-rheumatic drug. The goal of this study was to design passive targeting nanoparticles which could improve therapeutic efficacy and reduce side-effects such as nephrotoxicity and gastrointestinal disorders commonly associated with oral formulations of actarit. Based on the optimized results of single-factor and orthogonal design, actarit-loaded SLNs were prepared by a modified solvent diffusion–evaporation method. The formulated SLNs were found to be relatively uniform in size (241 ± 23 nm) with a negative zeta potential (−17.14 ± 1.6 mV). The average drug entrapment efficiency and loading were (50.87 ± 0.25)% and (8.48 ± 0.14)%, respectively. The actarit-loaded SLNs exhibited a longer mean retention time in vivo (t1/2(β), 9.373 h; MRT, 13.53 h) compared with the actarit 50% propylene glycol solution (t1/2(ke), 0.917 h; MRT, 1.323 h) after intravenous injection to New Zealand rabbits. The area under curve of plasma concentration–time (AUC) of actarit-loaded SLNs was 1.88 times greater than that of the actarit in 50% propylene glycol solution. The overall targeting efficiency (TEC) of the actarit-loaded SLNs was enhanced from 6.31% to 16.29% in spleen while the renal distribution of actarit was significantly reduced as compared to that of the actarit solution after intravenous administration to mice. These results indicated that injectable actarit-loaded solid lipid nanoparticles were promising passive targeting therapeutic agents for rheumatoid arthritis.