Effects of Vitamin C on Hyperoxia-Induced Reduction of Retinal Blood Flow
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.
Studieöversikt
Status
Betingelser
Studietyp
Inskrivning (Faktisk)
Fas
- Inte tillämpbar
Kontakter och platser
Studieorter
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Vienna, Österrike, 1090
- Department of Clinical Pharmacology
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Deltagandekriterier
Urvalskriterier
Åldrar som är berättigade till studier
Tar emot friska volontärer
Kön som är behöriga för studier
Beskrivning
Inclusion Criteria:
- Men aged between 19 and 35 years, nonsmokers
- Body mass index between 15th and 85th percentile (Must A 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
Studieplan
Hur är studien utformad?
Designdetaljer
- Primärt syfte: Diagnostisk
- Tilldelning: Randomiserad
- Interventionsmodell: Crossover tilldelning
- Maskning: Dubbel
Vapen och interventioner
Deltagargrupp / Arm |
Intervention / Behandling |
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Placebo-jämförare: 2
Placebo
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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
Substance: Physiologic saline solution 0.9% (placebo) Dosage form: i.v.
Dosage: 24ml/min over 64 min
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Aktiv komparator: 1
vitamin C (Mayrhofer)
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Substance: Ascorbic acid (Mayrhofer) Manufacturer: Mayrhofer, Linz, Austria Dosage form: i.v.
Dosage: 24mg/min over 64 min Dosage reference: Ting HH 1996
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 |
Vad mäter studien?
Primära resultatmått
Resultatmått |
Tidsram |
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Retinal arterial and venous diameter (Zeiss retinal vessel analyzer)
Tidsram: in total 6 hours
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in total 6 hours
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Retinal blood flow velocity (laser Doppler velocimetry)
Tidsram: in total 6 hours
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in total 6 hours
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Intraocular pressure (applanation tonometry)
Tidsram: in total 10 minutes
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in total 10 minutes
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Samarbetspartners och utredare
Sponsor
Studieavstämningsdatum
Studera stora datum
Studiestart
Primärt slutförande (Faktisk)
Avslutad studie (Faktisk)
Studieregistreringsdatum
Först inskickad
Först inskickad som uppfyllde QC-kriterierna
Första postat (Uppskatta)
Uppdateringar av studier
Senaste uppdatering publicerad (Uppskatta)
Senaste inskickade uppdateringen som uppfyllde QC-kriterierna
Senast verifierad
Mer information
Termer relaterade till denna studie
Ytterligare relevanta MeSH-villkor
Andra studie-ID-nummer
- OPHT-161202
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