Dopaminergic Modulation of Choroidal Blood Flow Changes During Dark/Light Transitions

Not Applicable

Completed

• Conditions: Regional Blood Flow; Ocular Physiology
• Interventions: Drug: Quetiapine (drug); Drug: Sulpiride (drug); Drug: Placebo

• Registration Number: NCT00280501
• Lead Sponsor: Medical University of Vienna

Brief Summary

There is evidence from a variety of animal studies that choroidal blood flow is under neural control. By contrast, only little information is available from human studies. Recent results indicate that a light/dark transition is associated with a reduction in choroidal blood flow due to an unknown mechanism. We have shown that during unilateral dark/light transitions both eyes react with choroidal vasoconstriction strongly indicating a neural mechanism responsible for the blood flow changes.

Dopamine has been discussed as a chemical messenger for light adaptation. However, dopaminergic effects in the eye are not restricted to synaptic sites of release, but dopamine also diffuses to the outer retinal layers and pigment epithelium. Accordingly, dopaminergic effects also include a modulatory role on retinal vessel diameter and animal studies provide evidence for vasodilatory effects in the choroid. There is evidence that during darkness retinal and choroidal dopamine levels decrease. Accordingly, dopamine could provide a modulatory input to the light/dark transition induced changes of choroidal circulation. The aim of the present study is to test this hypothesis.

Detailed Description

Not available

Study Timeline

• Study Start: 2005-08
• Study First Submitted: 2006-01-19
• Study First Submitted QC: 2006-01-19
• Study First Posted: 2006-01-23
• Primary Completion: 2006-08
• Study Completion: 2006-08
• Status Verified: 2008-07
• Last Update Submitted: 2008-07-08
• Last Update Posted: 2008-07-09

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Male
• Target Recruitment: 21

Inclusion Criteria

• Men aged between 18 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, ametropia < 3 Dpt.

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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

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
3	Quetiapine (drug)	Placebo
2	Sulpiride (drug)	Sulpiride
3	Sulpiride (drug)	Placebo
1	Placebo	Quetiapine
1	Quetiapine (drug)	Quetiapine
1	Sulpiride (drug)	Quetiapine
2	Quetiapine (drug)	Sulpiride
2	Placebo	Sulpiride
3	Placebo	Placebo

Primary Outcome Measures

Name	Time	Method
choroidal blood flow	in total 3x 3 hours
fundus pulsation amplitude	in total 3 x 3 hours

Trial Locations

Locations (1)

Department of Clinical Pharmacology; 🇦🇹 Vienna, Austria