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Sponsored by: |
Medical University of Vienna |
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Information provided by: | Medical University of Vienna |
ClinicalTrials.gov Identifier: | NCT00712907 |
High arterial blood oxygen tension leads to vasoconstriction of retinal vessels, possibly related to an interaction between reactive oxygen species and endothelium-derived vasoactive factors. Vitamin C is a potent antioxidant capable of reversing endothelial dysfunction due to increased oxidant stress.
Vitamin C appears to have vasodilatory properties, but the underlying mechanisms are not well understood.
In the present study we hypothesized that hyperoxic vasoconstriction of retinal vessels could be diminished by vitamin C.
Ocular blood flow will be determined by non-invasive methods, including laser Doppler velocimetry and the Zeiss retinal vessel analyser.
Condition | Intervention |
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Ocular Physiology Regional Blood Flow |
Dietary Supplement: vitamin C (Mayrhofer) 24mg/min i.v. for 64 min Dietary Supplement: Placebo Other: 100% O2 (AGA) two times for 12 min |
Study Type: | Interventional |
Study Design: | Diagnostic, Randomized, Double Blind (Subject, Investigator), Crossover Assignment, Safety/Efficacy Study |
Official Title: | Effects of Vitamin C on Hyperoxia-Induced Reduction of Retinal Blood Flow |
Enrollment: | 12 |
Study Start Date: | February 2003 |
Study Completion Date: | May 2003 |
Primary Completion Date: | May 2003 (Final data collection date for primary outcome measure) |
Arms | Assigned Interventions |
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1: Active Comparator
vitamin C (Mayrhofer)
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Dietary Supplement: vitamin C (Mayrhofer) 24mg/min i.v. for 64 min
Substance: Ascorbic acid (Mayrhofer) Manufacturer: Mayrhofer, Linz, Austria Dosage form: i.v. Dosage: 24mg/min over 64 min Dosage reference: Ting HH 1996
Other: 100% O2 (AGA) two times for 12 min
Substance: 100% oxygen (AGA, Vienna, Austria, gases for human use) Manufacturer: AGA, Vienna, Austria, gases for human use Dosage form: Inhalation through an oxygenmask over a period of 12 minutes two times per study day. Dosage reference: Strenn K 1997 |
2: Placebo Comparator
Placebo
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Dietary Supplement: Placebo
Substance: Physiologic saline solution 0.9% (placebo) Dosage form: i.v. Dosage: 24ml/min over 64 min
Other: 100% O2 (AGA) two times for 12 min
Substance: 100% oxygen (AGA, Vienna, Austria, gases for human use) Manufacturer: AGA, Vienna, Austria, gases for human use Dosage form: Inhalation through an oxygenmask over a period of 12 minutes two times per study day. Dosage reference: Strenn K 1997 |
Ages Eligible for Study: | 19 Years to 35 Years |
Genders Eligible for Study: | Male |
Accepts Healthy Volunteers: | Yes |
Inclusion Criteria:
Exclusion Criteria:
Responsible Party: | Department of Clinical Pharmacology ( Gabriele Fuchsjäger-Mayrl, MD ) |
Study ID Numbers: | OPHT-161202 |
Study First Received: | July 8, 2008 |
Last Updated: | July 9, 2008 |
ClinicalTrials.gov Identifier: | NCT00712907 History of Changes |
Health Authority: | Austria: Agency for Health and Food Safety |
vitamin C retinal blood flow intraocular pressure retinal vessel diameter |
Hyperoxia Antioxidants Vitamins |
Trace Elements Micronutrients Ascorbic Acid |
Antioxidants Molecular Mechanisms of Pharmacological Action Growth Substances Vitamins Physiological Effects of Drugs |
Micronutrients Protective Agents Pharmacologic Actions Ascorbic Acid |