Effects of Intravenous Clonidine on Ocular Blood Flow and Intraocular Pressure
Information source: Medical University of Vienna
Information obtained from ClinicalTrials.gov on June 20, 2008
Link to the current ClinicalTrials.gov record.
Condition(s) targeted: Physiology
Intervention: clonidine (drug) intravenously (Drug)
Phase: Phase 4
Status: Completed
Sponsored by: Medical University of Vienna Official(s) and/or principal investigator(s):
Gabriele Fuchsjaeger-Mayrl, MD, Principal Investigator, Affiliation: Department of Clinical Pharmacology
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.
Clinical Details
Study design: Treatment, Randomized, Double-Blind, Placebo Control, Crossover Assignment, Efficacy Study
Primary outcome: ocular blood flow
Eligibility
Minimum age: 19 Years.
Maximum age: 35 Years.
Gender(s): Male.
Criteria:
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
Locations and Contacts
Additional Information
Starting date: March 2004
Ending date: January 2005
Last updated: January 18, 2006
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