Effect of Levodopa on Human Multifocal Electroretinogram

Study Overview
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Brief Summary
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It is known that dopamine is a functional neuromodulator at several levels of the visual system. Dopamine seems to be involved in the organization of the ganglion cell and the bipolar cell receptive fields and modulation of physiological activity of photoreceptors. There is evidence for the functional significance of dopaminergic modulation of visual sensitivity in humans which confirms the hypothesis that dopamine plays an important role in retinal light adaptation as well as in motion and contrast sensitivity function. The electrophysiological effects of dopamine, various dopamine antagonist and levodopa in animals and humans have been investigated by means of visual evoked potentials and electroretinograms. The multifocal ERG technique, developed by Sutter et al. allows a rapid, simultaneous recording of focal ERGs from multiple retinal locations. Although this technique is relatively new, it has already provided insights into the mechanisms of retinal diseases (e.g. involvement of visual system in Parkinson disease), but until now there is no data on influence of dopaminergic substances on mERG.

Official Title
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Effect of Levodopa on Human Multifocal Electroretinogram

Conditions
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Retinal Diseases

Intervention / Treatment
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* Drug: levodopa


Participation Criteria
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Eligibility Criteria
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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, 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

Ages Eligible for Study
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Minimum Age: 19 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br> | Drug: levodopa<br>* 1 tablet of 200 mg levodopa plus 50 mg benserazide<br>* Other names: Madopar;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Retinal activity (mERG amplitude) |  | 5 measurements on both study days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Retinal activity (mERG latency) |  | 5 measurements on both study days | 
| Dopamine and levodopa plasma levels |  | on both study days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Electroretinography, levodopa