Overcoming Barriers: Controlled-Release Systems as Vectors, the Posterior Segment of the Eye Approach as a Model

Background: A successful therapy requires drug access to the target site. This is particularly complicated if the target is located in a well-protected location. Furthermore, if a chronic disease must be treated, the desirable system should be able to control drug release, maintain therapeutic concentrations during the necessary period and prolong administration needs.

Objective: To serve such purposes, the use of controlled-release systems as vectors has been suggested. This might be relevant, among other regions, in the posterior segment of the eye, a place where access is difficult due to different barriers.

Results: To achieve access, multiple strategies have been attempted. Dendrimers, microparticles and liposomes have been designed with varying success. The lack of clinical trials is an issue that must still be addressed.

Conclusion: These approaches are only the tip of the iceberg in terms of what pharmaceutical technology will develop over the next decades.