Pharmacokinetics and contact lenses: Drug release, delivery and fate

Abstract

Topical ocular instillation is the most common route of administration for ophthalmic drugs. Despite being an easy way of drug administration, the ocular drug bioavailability is low (<4% in the anterior chamber), and the duration of therapeutic effect is short, requiring frequent instillations.Controlled drug delivery systems such as contact lenses allow drug release onto the ocular surface for a longer time, which may improve ocular drug bioavailability and duration of action. Furthermore, such topical formulations may have the potential to deliver the drug to the posterior segment of the eye. Nevertheless, the ocular drug pharmacokinetics is not very well known, with a few studies published on contact lens delivery systems. In this presentation, we will take a closer look at this, describing the drug absorption and disposition processes in the eye, and clarifying some wrong assumptions. Research on drug release in tear fluid, corneal and non‐corneal absorption routes, and ocular drug disposition in the anterior and posterior segments are considered along with the quantitative pharmacokinetic data available up to now.Overall, this talk aims to provide better understanding on ocular pharmacokinetics and on the key aspects to consider when designing in vivo pharmacokinetics studies using contact lens delivery systems.Keywords: ocular pharmacokinetics, topical ophthalmic administration, non‐corneal absorption, contact lenses.