Document Detail

Drug delivery to the posterior segment from drops.
MedLine Citation:
PMID:  12204700     Owner:  NLM     Status:  MEDLINE    
The published evidence that instilled drugs can affect the blood supply to the retina and optic nerve head in humans is examined. As a background, seven techniques that have been used to measure flow are briefly described and criticized. For timolol, the corresponding measurements, obtained by a number of investigators are evaluated. The outcome is very erratic and does not allow any conclusion as to the effect of this drug on flow. Consideration is then given to the possible mechanism whereby a drug could affect blood flow; directly, by diffusion to receptors on the vessels, or indirectly, through more anterior receptors. The question is raised whether the small changes in circulation induced by drugs would not be swamped by those resulting from natural alterations in the ambient light level. The literature was analyzed in the hope of identifying discrete entry pathways, for example, through the lens or the suprachoroidal space, that are sufficiently permeable to allow a significant quantity of drug to pass. There was an indication that a drug might diffuse through the lens cortex in sufficient quantity to cause a measurable rise in its concentration in the vitreous. In general, however, there was insufficient quantitative data to allow any meaningful predictions to be made. Stimulated by recent evidence, it is suggested that drug penetration from the tear fluid takes place by direct diffusion across the conjunctiva into the sclera and orbit when the head is supine.
David M Maurice
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.; Review    
Journal Detail:
Title:  Survey of ophthalmology     Volume:  47 Suppl 1     ISSN:  0039-6257     ISO Abbreviation:  Surv Ophthalmol     Publication Date:  2002 Aug 
Date Detail:
Created Date:  2002-09-02     Completed Date:  2002-12-20     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0404551     Medline TA:  Surv Ophthalmol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  S41-52     Citation Subset:  IM    
Department of Ophthalmology, Columbia University, 630 West 168th Street, New York, NY 10032, USA.
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MeSH Terms
Administration, Topical
Antihypertensive Agents / pharmacokinetics*
Blood Flow Velocity / drug effects
Drug Delivery Systems
Glaucoma / drug therapy,  metabolism
Intraocular Pressure / drug effects
Ophthalmic Solutions / pharmacokinetics*
Optic Nerve / blood supply*
Regional Blood Flow
Retina / metabolism*
Retinal Vessels / physiology*
Vitreous Body / metabolism*
Grant Support
Reg. No./Substance:
0/Antihypertensive Agents; 0/Ophthalmic Solutions

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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