Effects of Intravenous Clonidine on Ocular Blood Flow and Intraocular Pressure

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: NCT00279253
Recruitment Status : Completed
First Posted : January 19, 2006
Last Update Posted : January 19, 2006
Information provided by:
Medical University of Vienna

Brief Summary:

Background Clonidine, a derivate of Imidazol, is an antihypertensive drug. It acts by stimulating adrenergic receptors on nerves in the brain and Imidazol-receptors. As a result, clonidine slows the heart rate and reduces blood pressure. Clonidine was approved by the FDA in 1974 and is registered in Austria with the brand name “Catapresan”.

Alpha2 adrenergic agonists are nowadays used topically as eye drops in glaucoma treatment. In addition to their known effect of lowering intraocular pressure, alpha2 adrenoceptor agonists are neuroprotective. Brimonidine, which is the most commonly used topical alpha-2 agonist, is currently on the market for treatment of glaucoma and is effective in reducing intraocular pressure. 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. Direct investigation of the ocular hemodynamic effects of brimonidine is, however, difficult, because lowering intraocular pressure with brimonidine may confound the results due to the concomitant change in ocular perfusion pressure.

The aim of the present study is to assess the effect of intravenous clonidine as model drug of alpha agonists on ocular blood flow and IOP in healthy humans.

Study objectives:

To investigate effects of clonidine on ocular blood flow and intraocular pressure.

Condition or disease Intervention/treatment Phase
Physiology Drug: clonidine (drug) intravenously Phase 4

Study Type : Interventional  (Clinical Trial)
Enrollment : 12 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double
Primary Purpose: Treatment
Study Start Date : March 2004
Study Completion Date : January 2005

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Primary Outcome Measures :
  1. ocular blood flow

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

Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant

Normal laboratory values unless the investigator considers an abnormality to be clinically irrelevant

Normal ophthalmic findings, ametropy < 3 Dpt.

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): NCT00279253

Sponsors and Collaborators
Medical University of Vienna
Principal Investigator: Gabriele Fuchsjaeger-Mayrl, MD Department of Clinical Pharmacology Identifier: NCT00279253     History of Changes
Other Study ID Numbers: OPHT-141003
First Posted: January 19, 2006    Key Record Dates
Last Update Posted: January 19, 2006
Last Verified: January 2006

Keywords provided by Medical University of Vienna:

Additional relevant MeSH terms:
Sensory System Agents
Peripheral Nervous System Agents
Physiological Effects of Drugs
Antihypertensive Agents
Autonomic Agents
Adrenergic alpha-2 Receptor Agonists
Adrenergic alpha-Agonists
Adrenergic Agonists
Adrenergic Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action