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

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00312416
Recruitment Status : Completed
First Posted : April 10, 2006
Last Update Posted : February 12, 2007
Information provided by:
Medical University of Vienna

Brief Summary:

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.

Condition or disease Intervention/treatment Phase
Ocular Physiology Regional Blood Flow Drug: Clonidin Drug: Brimonidine Phase 4

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Study Type : Interventional  (Clinical Trial)
Enrollment : 18 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double
Primary Purpose: Treatment
Official Title: Effects of Topical Clonidine vs. Brimonidine on Choroidal Blood Flow and Intraocular Pressure During Isometric Exercise
Study Start Date : February 2004
Study Completion Date : December 2004

Resource links provided by the National Library of Medicine

Primary Outcome Measures :
  1. Choroidal pressure-flow relationship

Information from the National Library of Medicine

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Ages Eligible for Study:   19 Years to 35 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes

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

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00312416

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Department of Clinical Pharmacology
Vienna, Austria, 1090
Sponsors and Collaborators
Medical University of Vienna
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Principal Investigator: Gabriele Fuchsjäger-Mayrl, M.D. Deapartment of Clinical Pharmacology, Medical University of Vienna
Layout table for additonal information Identifier: NCT00312416    
Other Study ID Numbers: OPHT-121203B
First Posted: April 10, 2006    Key Record Dates
Last Update Posted: February 12, 2007
Last Verified: February 2007
Keywords provided by Medical University of Vienna:
Choroidal blood flow
Additional relevant MeSH terms:
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Brimonidine Tartrate
Antihypertensive Agents
Adrenergic alpha-2 Receptor Agonists
Adrenergic alpha-Agonists
Adrenergic Agonists
Adrenergic Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Physiological Effects of Drugs