ABSTRACT
To evaluate routes and drug delivery systems designed to target the posterior segment of the eye, pharmacokinetic studies often dose drugs into the vitreous humor. However, few therapeutic targets are located in the vitreous, but rather are located within the retina, retinal pigment epithelium, or choroid. Depending on the route of administration and delivery systems, ef›cient concentrations can be achieved and maintained retina without being reached in the vitreous (Behar-Cohen et al. 2002). On the other hand, drug concentrations in the vitreous do not always parallel those
8.1 Introduction .................................................................................................. 159 8.1.1 Vitreous Humor: Its Structure and Relations with the Retina .......... 160 8.1.2 Drug Delivery to the Vitreous Humor: From Animal Models to
Clinical Applications ........................................................................ 161 8.1.3 Advantages of Drug Delivery to the Vitreous Humor ...................... 162 8.1.4 Limits of Drug Delivery to the Vitreous Humor .............................. 163
8.2 Drugs Delivery Systems into the Vitreous ................................................... 164 8.2.1 General Principles ............................................................................ 164
8.2.1.1 General Rules for Intravitreous Drug Release ................... 164 8.2.1.2 Tissue and Cell Targets: the Potential of Particulate
Systems .............................................................................. 165 8.2.1.3 Modalities and Kinetics or Intravitreous
Administration of Particulate Systems .............................. 170 8.2.2 Applications of Particulate Drug Delivery Systems to Eye
Diseases ............................................................................................ 171 8.2.2.1 Neurotrophic Factors for Retinal Degenerative Diseases ...... 171 8.2.2.2 Treatment of Infectious Retinitis ....................................... 173 8.2.2.3 Treatment of Proliferative Vitreo Retinopathy .................. 173 8.2.2.4 Treatment of Intraocular In•ammation ............................. 174
8.3 Future Directions toward Clinical Applications ........................................... 174 References .............................................................................................................. 174
achieved in the outer retina or in the choroid. Indeed, the vitreous humor is one among other ocular exchange compartments in the complex and not fully understood pharmacokinetic dynamic of the posterior segment of the eye.
