Bimatoprost loaded nanovesicular long-acting sub-conjunctival in-situ gelling implant: In vitro and in vivo evaluation

Abstract

Primary treatment for glaucoma relies on chronic instillation (daily) of intraocular pressure (IOP) lowering eye drops. Present study tends to develop and assess a novel sustained release bimatoprost loaded nanovesicular (BMT-NV) - thermosensitive in-situ gelling implant (BMT-NV- GEL-IM), for subconjunctival delivery. BMT-NVs developed using novel composition and method of preparation, (IPA/700/DEL/2014) and industrially viable methodology were characterized and evaluated comprehensively for ocular suitability. Their incorporation into an in-situ gelling formula was safe (in vitro and in vivo) and stable upon sterilization. Autoclavability was an important consideration, as a preservative-free, single-use BMT-NV- GEL-IM will avoid side- effects associated with repetitive application of drops containing preservatives like benzalkonium chloride (BAK). An extended in vitro release of BMT (80.23%) was observed for 10 days while the IOP lowering effect extended over 2 months with single subconjunctival injection of BMT-NV-GEL-IM in rats. No clinical signs of irritation, inflammation, or infection were observed in any injected eye, throughout the study, as also confirmed by histology. Furthermore, single administration of BMT-NV-GEL as topical drop lowered the IOP over 5 days. Presence of significant diffuse fluorescence in confocal microscopy of internal eye tissues post-in vivo application, as subconjunctival implant, even after 2 month and eye drops upto1 week provide direct evidence of successful sustained delivery. We thus provide an improved modality for antiglaucoma medication in patients who are challenged to adhere to a regimen of daily eye drops.