Extended ocular drug delivery systems for the anterior and posterior segments: biomaterial options and applications

ABSTRACT

Introduction: The development of new therapies for treating various eye conditions has led to a demand for extended release delivery systems, which would lessen the need for frequent application while still achieving therapeutic drug levels in the target tissues.

Areas covered: Following an overview of the different ocular drug delivery modalities, this article surveys the biomaterials used to develop sustained release drug delivery systems. Microspheres, nanospheres, liposomes, hydrogels, and composite systems are discussed in terms of their primary materials. The advantages and disadvantages of each drug delivery system are discussed for various applications. Recommendations for modifications and strategies for improvements to these basic systems are also discussed.

Expert opinion: An ideal sustained release drug delivery system should be able to encapsulate and deliver the necessary drug to the target tissues at a therapeutic level without any detriment to the drug. Drug encapsulation should be as high as possible to minimize loss and unless it is specifically desired, the initial burst of drug release should be kept to a minimum. By modifying various biomaterials, it is possible to achieve sustained drug delivery to both the anterior and posterior segments of the eye.

KEYWORDS:

• Anterior segment delivery
• drug delivery
• eye
• hydrogels
• liposomes
• microspheres
• nanospheres
• PLGA
• posterior segment delivery

Article highlights

• Topical, systemic, transcleral, periocular, and intravitreal drug delivery modalities are discussed.

• Microspheres, nanospheres, liposomes, hydrogels, and composite drug delivery systems are evaluated.

• Products undergoing clinical trials are reviewed and discussed.

• Biomaterials used to improve drug bioavailability, release, and delivery are considered.

• The future of sustained release ocular drug delivery systems is discussed.

This box summarizes key points contained in the article.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Additional information

Funding

This paper was not funded.