Current topical eye drop formulations, in addition to often eliciting some degree of transient irritation, provide only short term exposure of beneficial agents to the eye and thus often require several administrations daily. Other modes of drug delivery, such as oral delivery and injection, may result in high and low blood concentrations and/or shortened half-life in the blood, in addition to systemic delivery of medicaments that are only required in the eye. In some cases, achieving therapeutic efficacy with these standard administrations requires large doses of medications that may result in toxic side effects. Additionally, some eye drop formulations are unstable over the normal period of treatment, which may be exacerbated by patient mis-handling. The technologies relating to controlled drug release have been attempted in an effort to circumvent some of the pitfalls of conventional therapy. Their aims are to deliver medications on a continuous and sustained manner.
There remains a need for a more economical, practical, and efficient way of producing and manufacturing drug delivery systems that may be used locally, in liquid, gel, or ointment formulations. In particular, there remains a need for sustained-release formulations for topical administrations (eye drops) of beneficial, active agents to the eye.