Abstract
To date, nearly all ocular therapeutics have been administered to the eye as simple aqueous solution eyedrops by instillation to the lower conjunctival sac. The main drawbacks of aqueous eyedrops are their inability to deliver lipophilic and insoluble molecules, their low retention time, and their limited ability to resist the washout effect of blinking and tears turnover. The expected 10% to 20% fraction of the applied topical dose that escapes the immediate washout by blinking and tearing is then challenged by tear fluid proteins and enzymes binding and metabolism, ocular permeation barriers, phagocytic activity and partial diversion to adjacent tissues, and systemic circulation. Thus, more drug elimination occurs before it reaches the target tissue. Therefore, it is estimated that only 1% or less of the administered dose can penetrate the ocular surface [1,2]. Moreover, when targeting a remote target tissue like the retina, the fraction of the administered dose that reaches the action site will be much less due to further anatomical barriers, aqueous humor turnover, intraocular metabolic activity, binding to intraocular pigmented tissues, and phagocytosis by cell line other than the targeted tissue cells.
Original language | English |
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Title of host publication | Enhancement in Drug Delivery |
Publisher | CRC Press |
Pages | 490-525 |
Number of pages | 36 |
ISBN (Electronic) | 9781420004816 |
ISBN (Print) | 9780849332036 |
State | Published - 1 Jan 2006 |
Bibliographical note
Publisher Copyright:© 2011 by Taylor & Francis Group, LLC.