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

Sponsor

Medical University of Vienna (Other)

Overall Status

Completed

CT.gov ID

NCT00280501

Collaborator

(none)

Enrollment

Location

Arms

Duration (Months)

1.8

Patients Per Site Per Month

Study Details

Study Description

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.

Condition or Disease	Intervention/Treatment	Phase
Regional Blood Flow Ocular Physiology	Drug: Quetiapine (drug) Drug: Sulpiride (drug) Drug: Placebo	N/A

Study Design

Study Type:

Interventional

Actual Enrollment :

21 participants

Allocation:

Randomized

Intervention Model:

Crossover Assignment

Masking:

Double (Participant, Investigator)

Primary Purpose:

Treatment

Official Title:

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

Study Start Date :

Aug 1, 2005

Actual Primary Completion Date :

Aug 1, 2006

Actual Study Completion Date :

Aug 1, 2006

Arms and Interventions

Arm	Intervention/Treatment
Active Comparator: 1 Quetiapine	Drug: Quetiapine (drug) Quetiapine (Seroquel 100mg-film-coated tablet, AstraZeneca Vienna, Austria) Dose: 100 mg tablet oral single dose Drug: Sulpiride (drug) Sulpiride (Dogmatil 200mg-tablet, Synthélabo Groupe, Le Plessis Robinson, France) Dose: one half of 200 mg tablet oral single dose Drug: Placebo Placebo
Active Comparator: 2 Sulpiride	Drug: Quetiapine (drug) Quetiapine (Seroquel 100mg-film-coated tablet, AstraZeneca Vienna, Austria) Dose: 100 mg tablet oral single dose Drug: Sulpiride (drug) Sulpiride (Dogmatil 200mg-tablet, Synthélabo Groupe, Le Plessis Robinson, France) Dose: one half of 200 mg tablet oral single dose Drug: Placebo Placebo
Placebo Comparator: 3 Placebo	Drug: Quetiapine (drug) Quetiapine (Seroquel 100mg-film-coated tablet, AstraZeneca Vienna, Austria) Dose: 100 mg tablet oral single dose Drug: Sulpiride (drug) Sulpiride (Dogmatil 200mg-tablet, Synthélabo Groupe, Le Plessis Robinson, France) Dose: one half of 200 mg tablet oral single dose Drug: Placebo Placebo

Arm

Intervention/Treatment

Active Comparator: 1

Quetiapine

Drug: Quetiapine (drug)

Quetiapine (Seroquel 100mg-film-coated tablet, AstraZeneca Vienna, Austria) Dose: 100 mg tablet oral single dose

Drug: Sulpiride (drug)

Sulpiride (Dogmatil 200mg-tablet, Synthélabo Groupe, Le Plessis Robinson, France) Dose: one half of 200 mg tablet oral single dose

Drug: Placebo

Placebo

Active Comparator: 2

Sulpiride

Drug: Quetiapine (drug)

Quetiapine (Seroquel 100mg-film-coated tablet, AstraZeneca Vienna, Austria) Dose: 100 mg tablet oral single dose

Drug: Sulpiride (drug)

Sulpiride (Dogmatil 200mg-tablet, Synthélabo Groupe, Le Plessis Robinson, France) Dose: one half of 200 mg tablet oral single dose

Drug: Placebo

Placebo

Placebo Comparator: 3

Placebo

Drug: Quetiapine (drug)

Quetiapine (Seroquel 100mg-film-coated tablet, AstraZeneca Vienna, Austria) Dose: 100 mg tablet oral single dose

Drug: Sulpiride (drug)

Sulpiride (Dogmatil 200mg-tablet, Synthélabo Groupe, Le Plessis Robinson, France) Dose: one half of 200 mg tablet oral single dose

Drug: Placebo

Placebo

Outcome Measures

Primary Outcome Measures

choroidal blood flow [in total 3x 3 hours]
fundus pulsation amplitude [in total 3 x 3 hours]

Eligibility Criteria

Criteria

Ages Eligible for Study:

18 Years to 35 Years

Sexes Eligible for Study:

Male

Accepts Healthy Volunteers:

Yes

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.

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