Development of In-Situ Gel Containing Brinzolamide loaded Nano Structured Lipid Carrier and Its Evaluation

Ocular drug delivery system is most challenging and complicated to deliver drugs at the target site with its therapeutic dose. Intraocular bioavailability is only 5 to10 % of total eye drop administered. In past few decades, researchers have attracted to nanotechnology based drug delivery system in which lipid based Nanostructured lipid carriers (NLC) appear as effective ophthalmic drug delivery system, which have, higher drug loading, stability and biocompatibility as compare to other lipid carried due to use of physiologically biodegradable lipid. The Nanostructure carrier provides more retention time, better permeation, targeted delivery, improve bioavailability, Non-toxic. Now a days, the conventional eye drops replace by Polymeric eye drop i.e. <i>in-situ gel</i>, they are liquid in nature after instillation it undergoes gelation to form viscoelastic gels triggered by stimulation such as temperature, pH and ion activation. Consequently, gel formed increases residence time, extended drug release, enhances bioavailability, reduce dosing frequency and patient compliance.The aim of this work to develop and evaluate <i>in-situ</i> gel containing Brinzolamide loaded Nano structured lipid carrier to increase its retention time, Bioavailability, Corneal permeation, reduce dose and dosing frequency.<br/>The saturation solubility study was used to select liquid lipid. The solubility of Brinzolamide was determined in several solid lipids such as Bees wax, Stearic acid, Gelucure50/13, Palmitic acid, Glyceryl mono stearate (GMS), Precirol ATO, Compritol ATO 888, cetyl palmitate. Compatibility between selected lipids was examine by preparing mixture of solid lipid and liquid lipid in a ratios of 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8 and 1:9. Only one single phase Mixtures were selected for further study. High speed homogenization method was used to prepare Brinzolamide loaded NLCs. A three-factor, three-level Box–Behnken design experimental design (BBD) was applied for evaluation of critical experimental conditions to maximize experimental efficiency and minimize experiments to optimize The particle size and particle dispersity index ( PDI) of the NLCs was determined using the dynamic light scattering (DLS) at a fixed angle of 90 degree at 25 degree C using Nanophox, Sympatech, Germany .The ZP of BRZ-NLC was determined by using zeta sizer (Delsa Nano C, USA) to check electrostatic mobility and stability of formulaton. The entrapment efficiency (% EE) of BEZ in NLC formulation was determined The physical state of BRZ-loaded nanostructured lipid carriers demonstrated by DSC characterization technique. BRZ-loaded NLC <i>in situ </i>gel was prepared by the cold method. The drug content was determined by HPLC. In vitro release of BRZ-loaded NLC <i>in situ</i> gel was studied on Franz diffusion cell. Transcorneal permeation studies were carried out on freshly excised goat cornea. HET CAM (Hen's egg chorioallantoic membrane) study is an alternative to the Draize <i>in-vivo</i> rabbit eye test for the recognition of ocular irritations. Therapeutic activity study was conducted with albino rabbits (1.5–2 kg) under the permission of Institutional Animal Ethics Committee (IAEC).<br/>From solubility data Gelucire 50/13 and Oleic acid were selected as the solid and liquid lipid for NLC preparation. Amongst various ratios of solid and liquid lipid 9:1, 8:2, 7:3, 6:4, and 5:5 no phase separation and homogenous mixture was observed for 8:2 ratio, this were selected as lipids mixture. The SEM analysis reveals that spherical and smooth surface of NLC with uniform distribution of particles. BRZ content in formulated <i>in situ </i>gel was determined and found to be in range of 99.34-98.58%.BRZ-NLC shows rapid release of drug (68.33%) within 4 h and within 7 h it completely releases (94.33%) drug.This initial raid release of drug due to the unentrapped drug which release from NLC) Whereas, BRZ-NLC <i>in situ </i>have extended and slow release of drug (96.44%) up to 15 h.