Evaluation of precorneal residence time of brimonidine tartrate nanoparticles loaded in situ gel using gamma scintigraphy.

In this study, brimonidine tartrate (BRT) based vitamin E tocopheryl polyethylene glycol succinate (TPGS) nanoparticles loaded in situ gel was developed with aim for improvement of drug ocular retention time. Nanoparticle formulation (PS-1) comprising of PLGA (0.1%w/v) and vitamin E TPGS (0.4%w/v) was characterized. It was revealed that formulation exhibited 123.70 ± 0.12 nm, 0.356 ± 0.02, 82.20 ± 2.32% and − 9.85 ± 0.08 mV of mean particle size, polydispersibility index (PDI), percentage entrapment efficiency (% EE) and zeta potential, respectively. Furthermore, optimized nanoparticles (PS-1) were incorporated into poloxamer 407 based in situ system. Formulation upon in vivo ocular tolerability tests were found to be well tolerated. Results showed that nanoparticles loaded in situ gel exhibited sustained and high residence time compared to marketed formulation in animals. Radio-imaging studies demonstrated that radiolabeled nanoparticles loaded in situ gel was effectively retained on corneal surface for longer duration. [ABSTRACT FROM AUTHOR]