The need for controlled, sustained-release drug delivery systems has been recognized by the ophthalmic community and industry. Such systems aim to circumvent the problems of drug bioavailability, sustainability and feasibility of the system as well as reduce the effect of the single major cause of poor therapeutic response from poor patient compliance. The technology offers a biodegradable sub-conjunctival shape-memory implant that provides steady and sustained drug release over a period of several weeks to months. The implantation of the microfilm into the sub-conjunctival space is a single, simple and non-invasive procedure. It degrades to non-toxic metabolites with time, hence no extra procedure is needed to remove the implant after the depletion of the drug. Furthermore, the microfilm has the capacity to be customized to deliver different drug release profiles depending on different clinical scenarios.
The biodegradable ocular implant has a drug loaded polymer matrix capable of containing a drug dispersed or dissolved therein. The biodegradabale polymer is poly(L-lactide-co-e-caprolactone; PA-PLC) and PLC is a relatively new copolymer made of poly(L-lactide) and poly(e-caprolactone), each of which has been approved by FDA and CE as implantable products. The drug is dispersed in the layer such that a higher concentration of the drug is found at the surface of each of the respective layers. When the surface starts to degrade, a higher concentration of the drug present at the surface is released. With the surface eroding over time, the concentration of the drug available in the remaining regions of the layer gets depleted and the rate of drug release slows down gradually. Providing a steady and sustainable dosage to be released over a period of time, this technology improves patient compliance and also yields a higher bioavailability which in turn ensures adequate drug potency, reduces drug wastage and avoids systemic toxicity. Single or multiple drugs can be incorporated between layers in a multi-layered polymer system that is 0.1 to 10 microns thick wherein there is controlled and directional release of the drugs with predictable layer by layer erosion. The biodegradable construct assumes a desired shape, allows easy insertion into the sub-conjunctival space of the eye and provides good subsequent anchorage. The implant can be placed into the sub-conjunctival space using a simple and quick technique that is minimally invasive and can be easily retrieved from the eye.
The biodegradable sustained drug delivery system has been evaluated to be as effective as conventional eye drops in delaying graft rejection and reducing the immune response after allogeneic corneal transplantation in a rat model. Hence, the biodegradable implant provides a promising therapeutic alternative to topical eye drops for patients undergoing cataract surgery and corneal transplant. It is to be used following commonly performed ophthalmic procedures such as cataract surgery, glaucoma surgery and corneal grafting as well as for treating uveitis and ocular allergies, providing effective prolonged steroid release.
Sustained release ocular drug delivery platforms are designed to meet the requirements like specific duration of effects, ranging from weeks to months, which are essential for therapeutic effect in different ophthalmic conditions. Sustained drug delivery is preferred in patients where repeated long-term administration is necessary to control the disease, and to overcome the disadvantages of topical medications and the issues with compliance. Clinical importance of such technology becomes evident for retinal drug delivery, when a drug-loaded liposome containing, for example an anti-angiogenesis factor, can be delivered into the back of the eye and that provides an optimal steady release of drug to treat retinal disorders. A single dose can last for weeks or months. As a result, it reduces the frequency of injections needed, effectively cancelling the substantial compliance issue prevalent with topical ophthalmic drugs.