Biodegradable scleral implant for controlled intraocular delivery of betamethasone phosphate

Abstract

We evaluated nail-like, biodegradable scleral implants as a controlled intraocular delivery system of betamethasone phosphate (BP) for the treatment of chronic uveitis using pigmented rabbits. The scleral implants, which contained 10% and 25% of BP (weight 8.5 mg; length 5 mm), were made of poly (D,L-lactide-co-glycolide) (PLGA). In vivo release and retinal toxicity after implantation were also studied in pigmented rabbits. The in vitro release studies demonstrated the 10% and 25% BP-loaded scleral implants released BP in a biphasic release pattern for at least 1 month. The BP concentrations in the vitreous and the retina/choroid after application of scleral implants in pigmented rabbit eyes stayed within the concentration range capable of suppressing inflammatory responses for over 1 month. The BP concentration was greater in the retina/choroid than in the vitreous throughout the study. No substantial toxic reactions in the retina were observed by electroretinography. Our findings suggest that the BP-loaded scleral implant may be a promising device for treatment of chronic uveitis.

A review of evidence guiding the use of corticosteroids in the treatment of intraocular inflammation

“…115 A sustained-release betamethasone phosphate implant that has the shape of a nail or tack has been designed to be inserted through the pars plana with the head remaining external, and to release the drug from the pointed tip. 77 This implant, which appeared safe when tested in rabbits, is unusual in its configuration as well as in delivering intraocular betamethasone, a drug for which the commercially available injectable formulation is not suitable for intraocular use, due to the preservative vehicle. 116 In addition to treating active inflammation, intravitreous triamcinolone also appears to be effective in reducing CME, as evidenced by angiography 117 and optical coherence tomography (OCT).…”

Biocompatibility and Biodegradation Studies of Subconjunctival Implants in Rabbit Eyes

“…Topical application is the mainstay of most ocular therapy, but ocular bioavailability is poor due to the efficient protective barriers [1], [2], [3]. The recognition of this limitation in efficient ocular drug delivery has led to a range of systems that vary in mode of administration, implantation site, composition and vehicles [4], [5], [6], [7], [8], [9], [10], [11], [12], which all aim to circumvent the problems of drug bioavailability, sustainability and feasibility of administration [13].…”

Periocular corticosteroids in diabetic papillopathy

“…Intraocular and periocular corticosteroids reduced the breakdown of blood-retinal barrier 18 partly by downregulating the production of vascular permeability growth factor, also known as vascular endothelial growth factor (VEGF). [19][20][21][22] Periocular corticosteroids reached the posterior segment of the eye experimentally 19,20,23,24 and clinically. 21,22 Superonasal injections allowed a high drug concentration around the optic nerve head, 23 while superotemporal injections allowed a high drug concentration around the macular region.…”