Development and Evaluation of Novel Polymeric Nanoparticles of Brimonidine Tartrate

Micro and nanoparticulate carriers have been in focus in ophthalmic drug delivery with the objective of improving bioavailability, drug targeting and reducing pulse entry of the drug in ocular cul de sac. Polymeric nanoparticles for ocular purpose have potential in reducing the pulse entry and frequency of dosing, thus improving patient compliance. In the present study, mucoadhesive sodium alginate nanoparticles were developed for Brimonidine Tartrate (BT) as a model antiglaucoma drug by controlled ionic gelation technique. These nanoparticles would not only prolong drugs residence time but also reduce pulse entry in cul de sac. Nanoparticles were evaluated for morphology, surface characteristics, drug polymer interactions, particle size, polydispersibility index, zeta potential, entrapment efficiency, in vitro release profile and in vivo efficacy. The effect of various stabilizers on stabilization of blank and drug loaded nanoparticles was investigated. Irregular shape and loss of crystallinity for BT loaded sodium alginate nanoparticles was observed by TEM and SEM images respectively. IR spectra and DSC thermograms revealed the physicochemical interaction was involved during sodium alginate nanoparticle formation and entrapment of BT. The developed nanoparticles have average particle size of 450nm with PI 0.65, the entrapment efficiency ranged from 4-18 % and zeta potential values ranged from -27.5 mV to -24.1 mV. In vitro release profile showed a gradual drug release over the period of 3 hrs. In-vivo experiments showed that it was possible to prolong the drug release over a period of 8 hr, on topical instillation of BT loaded nanoparticles to albino rabbits, hence reducing the dosage frequency.