Effects of Topical Clonidine vs. Brimonidine on Choroidal Blood Flow and Intraocular Pressure During Isometric Exercise

Brimonidine tartrate is an alpha-2 agonist ocular hypotensive drug that exerts its effect by causing both a decrease in aqueous production and an increase in uveoscleral outflow. It has been proven to reduce increased intraocular pressure in glaucoma and ocular hypertension. As an alpha 2 agonist Brimonidine belongs to the same class of drugs as Clonidine; however, its molecular structure is sufficiently different to make it more selective for the alpha 2 receptor than Clonidine. Unlike Clonidine, Brimonidine does not appear to have an effect on the central nervous system and therefore does not cause sedation or systemic hypotension.

In addition to their known effect of lowering intraocular pressure, alpha 2 adrenoceptor agonists are neuroprotective. It has, however, been shown that Brimonidine is a very potent vasoconstrictor in the ciliary body thus reducing aqueous humor production. Little is, however, known about potential vasoconstrictor effects of Brimonidine in the posterior pole of the eye. This is of clinical importance, because optic nerve head ischemia appears to contribute to glaucoma pathophysiology.

This study is performed to investigate the effects of topical Clonidine vs. topical Brimonidine on choroidal blood flow and intraocular pressure during isometric exercise.

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Key information

Conditions

Ocular Physiology Regional Blood Flow

Age range

19 year–35 year

Sex eligibility

Male

Study type

Interventional

Phase

Phase 4

Primary location

Department of Clinical Pharmacology

Vienna, 1090, Austria

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Men aged between 19 and 35 years, nonsmokers
Body mass index between 15th and 85th percentile (Must A et al. 1991)
Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
Normal ophthalmic findings, ametropy < 3 Dpt.
Intraocular pressure between 10 and 18 mmHg.

Exclusion criteria

Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study
Treatment in the previous 3 weeks with any drug
Symptoms of a clinically relevant illness in the 3 weeks before the first study day
History of hypersensitivity to the trial drug or to drugs with a similar chemical structure
History or presence of gastrointestinal, liver or kidney disease, or other conditions known to interfere with, distribution, metabolism or excretion of study drugs
Blood donation during the previous 3 weeks
History or family history of epilepsy

Treatment and study plan

Clonidin

Drug

Brimonidine

Drug

Primary outcomes

Choroidal pressure-flow relationship

Sponsors and collaborators

Lead sponsor

Medical University of Vienna

Other

Registry information

Important dates

Study start: 2004
Study completion: 2004
First posted: Apr 10, 2006
Registry last updated: Feb 12, 2007

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.

Completed