Role of Nitrogen Oxide (NO) in the Control of Choroidal Blood Flow During a Decrease in Ocular Perfusion Pressure

NCT ID: NCT00810927

Last Updated: 2008-12-18

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

Get a concise snapshot of the trial, including recruitment status, study phase, enrollment targets, and key timeline milestones.

Recruitment Status

COMPLETED

Clinical Phase

PHASE2

Total Enrollment

22 participants

Study Classification

INTERVENTIONAL

Study Start Date

2003-09-30

Study Completion Date

2005-08-31

Brief Summary

Review the sponsor-provided synopsis that highlights what the study is about and why it is being conducted.

Autoregulation is the ability of a vascular bed to maintain blood flow despite changes in perfusion pressure. For a long time it had been assumed that the choroid is a strictly passive vascular bed, which shows no autoregulation. However, recently several groups have identified some autoregulatory capacity of the human choroid. In the brain and the retina the mechanism behind autoregulation is most likely linked to changes in transmural pressure. In this model arterioles change their vascular tone depending on the pressure inside the vessel and outside the vessel. In the choroid, several observations argue against a direct involvement of arterioles. However, the mechanism behind choroidal autoregulation remains unclear.

In the present study autoregulation of the choroid will be investigated during a decrease in ocular perfusion pressure, which will be achieved by an increase in intraocular pressure. Pressure/flow relationships will be investigated in the absence or presence of a NO synthase inhibitor. As a control substance the alpha-receptor agonist phenylephrine will be used.

Detailed Description

Dive into the extended narrative that explains the scientific background, objectives, and procedures in greater depth.

Conditions

See the medical conditions and disease areas that this research is targeting or investigating.

Physiology, Ocular Microcirculation Regional Blood Flow Autoregulation

Study Design

Understand how the trial is structured, including allocation methods, masking strategies, primary purpose, and other design elements.

Allocation Method

RANDOMIZED

Intervention Model

CROSSOVER

Primary Study Purpose

TREATMENT

Blinding Strategy

TRIPLE

Participants Investigators Outcome Assessors

Study Groups

Review each arm or cohort in the study, along with the interventions and objectives associated with them.

1

Phenylephrine (Neosynephrine®, Abbott Laboratories, North Chicago, IL, USA) dose: 1µg/(kg.min), infusion period 20 minutes

Group Type ACTIVE_COMPARATOR

Suction cup application

Intervention Type PROCEDURE

he IOP will be raised by a 11 mm diameter, standardized suction cup placed on the temporal sclera with the anterior edge at least 1 mm from the limbus.

Laser Doppler flowmetry

Intervention Type PROCEDURE

Measurement of choroidal blood flow

Measurement of intraocular pressure

Intervention Type PROCEDURE

2

NG-monomethyl-L-arginine (L-NMMA, Clinalfa, Läufelfingen, Switzerland) dose: bolus 6mg/kg over 5 minutes followed by a continuous infusion of 60µg/(kg.min) over 15 minutes

Group Type ACTIVE_COMPARATOR

Suction cup application

Intervention Type PROCEDURE

he IOP will be raised by a 11 mm diameter, standardized suction cup placed on the temporal sclera with the anterior edge at least 1 mm from the limbus.

Laser Doppler flowmetry

Intervention Type PROCEDURE

Measurement of choroidal blood flow

Measurement of intraocular pressure

Intervention Type PROCEDURE

3

Physiologic saline solution

Group Type PLACEBO_COMPARATOR

Suction cup application

Intervention Type PROCEDURE

he IOP will be raised by a 11 mm diameter, standardized suction cup placed on the temporal sclera with the anterior edge at least 1 mm from the limbus.

Laser Doppler flowmetry

Intervention Type PROCEDURE

Measurement of choroidal blood flow

Measurement of intraocular pressure

Intervention Type PROCEDURE

Interventions

Learn about the drugs, procedures, or behavioral strategies being tested and how they are applied within this trial.

Suction cup application

he IOP will be raised by a 11 mm diameter, standardized suction cup placed on the temporal sclera with the anterior edge at least 1 mm from the limbus.

Intervention Type PROCEDURE

Laser Doppler flowmetry

Measurement of choroidal blood flow

Intervention Type PROCEDURE

Measurement of intraocular pressure

Intervention Type PROCEDURE

Eligibility Criteria

Check the participation requirements, including inclusion and exclusion rules, age limits, and whether healthy volunteers are accepted.

Inclusion Criteria

* Men aged between 19 and 35 years, nonsmokers
* Body mass index between 15th and 85th percentile (Must et al. 1991)
* 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, ametropia \< 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
Minimum Eligible Age

19 Years

Maximum Eligible Age

35 Years

Eligible Sex

MALE

Accepts Healthy Volunteers

Yes

Sponsors

Meet the organizations funding or collaborating on the study and learn about their roles.

Medical University of Vienna

OTHER

Sponsor Role lead

Responsible Party

Identify the individual or organization who holds primary responsibility for the study information submitted to regulators.

Department of Clinical Pharmacology, Medical University of Vienna

Principal Investigators

Learn about the lead researchers overseeing the trial and their institutional affiliations.

Gabriele Fuchsjäger-Mayrl, MD

Role: PRINCIPAL_INVESTIGATOR

Department of Clinical Pharmacology, Medical University of Vienna

Locations

Explore where the study is taking place and check the recruitment status at each participating site.

Department of Clinical Pharmacology, Medical University of Vienna

Vienna, , Austria

Site Status

Countries

Review the countries where the study has at least one active or historical site.

Austria

Other Identifiers

Review additional registry numbers or institutional identifiers associated with this trial.

OPHT-270602

Identifier Type: -

Identifier Source: org_study_id