Design, optimization and pharmacokinetic evaluation of PLGA phosphatidylcholine hybrid nanoparticles of triamcinolone acetonide loaded in situ gel for topical ocular delivery.

Posterior uveitis (PU), which often has an autoimmune origin, can be treated effectively with synthetic glucocorticoid triamcinolone acetonide (TAA). Due to the limitations of topical TAA administration reaching the posterior segment of the eye, the drug is injected directly into the eye through an intravitreal injection. In this study, we prepared TAA loaded poly(lactic-co-glycolic acid) phosphatidylcholine hybrid nanoparticles (TAA-PLHNPs) using the principles of design of experiments (DoE) for topical ocular administration. The mean particle size (nm) and drug loading efficiency (LE%) for the optimized formulations were 163 ± 2.8 nm and 39 ± 1.9%, respectively. The TAA-PLHNPs were then loaded into the dual responsive in situ gel that we reported in our previous work. In vitro assessments were done to show that the formulations are safe for ocular administration. Finally, in vivo ocular pharmacokinetic studies were performed to compare pharmacokinetic parameters of TAA-PLHNPs and TAA-PLHNPs loaded in situ gel with each other and with the previously reported conventional formulation of TAA (aqueous suspension of TAA with 20% hydroxypropyl β-cyclodextrin (TAA-HP-β-CD-Susp)). TAA-PLHNPs loaded dual responsive in situ gel (TAA-PLHNP-ISG) achieved higher concentrations of TAA in the vitreous humor (C of 946.53 ng/mL) and sustained (MRT of 16.26 h) the drug concentrations for longer period of time compared to aqueous suspension of TAA-PLHNPs (TAA-PLHNP-Susp) and TAA-HP-β-CD-Susp.