Ocular Hemodynamic Effects of Nitrovasodilators in Healthy Subjects

Sponsor

Medical University of Vienna (Other)

Overall Status

Completed

CT.gov ID

NCT00810381

Collaborator

(none)

Enrollment

Location

Arms

Duration (Months)

2.8

Patients Per Site Per Month

Study Details

Study Description

Brief Summary

Glaucoma, one of the most common causes of blindness, is associated with increased intraocular pressure (IOP) and optic nerve head ischemia. Nitrovasodilators are discussed in the treatment of glaucoma. Nitrates relax smooth muscle cells in the vasculature by liberating the vasodilator nitric oxide.

The IOP lowering potential and the vasodilator action in retinal and choroidal vessels of nitrates is still a matter of controversy. Previous studies on the ocular hemodynamic effects of nitrates showed partially contradicting results. In addition the IOP lowering effect of nitrates is still unclear. However, recent studies show that long acting nitrates may preserve optic nerve deterioration and visual field loss.

Therefore, the role of nitrovasodilators in control of ocular blood flow and intraocular pressure has to be elucidated. For this purpose the investigators plan to test the hypothesis that nitrovasodilators improve ocular blood supply to the optic nerve head at doses which do not affect systemic hemodynamics.

Condition or Disease	Intervention/Treatment	Phase
Glaucoma	Drug: Nitroglycerin Drug: Isosorbide-Dinitrate Drug: Sodium-nitroprusside Drug: Physiologic saline solution (control substance)	N/A

Study Design

Study Type:

Interventional

Actual Enrollment :

14 participants

Allocation:

Randomized

Intervention Model:

Crossover Assignment

Masking:

Triple (Participant, Investigator, Outcomes Assessor)

Primary Purpose:

Basic Science

Official Title:

Ocular Hemodynamic Effects of Nitrovasodilators in Healthy Subjects

Study Start Date :

Jan 1, 1999

Actual Primary Completion Date :

Jun 1, 1999

Actual Study Completion Date :

Jun 1, 1999

Arms and Interventions

Arm	Intervention/Treatment
Active Comparator: 1 Nitroglycerin: (Perlinganit, Nycomet Heilmittelwerke, Vienna, Austria): 0, 0.25, 0.5, 1, 1.5 and 2 µg/kg/min, each infusion step for 20 minutes	Drug: Nitroglycerin intravenous infusion; 0, 0.125, 0.25, 0.5, 1 and 2 µg/kg/min; 20 minutes per infusion step
Active Comparator: 2 Isosorbide-Dinitrate: (Isoket 0,1 %, Gebro Broschek, Fieberbrunn, Austria): 0, 0.5, 1, 2, 4 and 6 µg/kg/min , each infusion step for 20 minutes	Drug: Isosorbide-Dinitrate intravenous infusion; 0, 0.5, 1, 2, 4, and 6 µg/kg/min; 20 minutes per infusion step
Active Comparator: 3 Sodium-Nitroprusside: (Nipruss, Sanol-Schwarz, Monheim, Germany): 0, 0.25, 0.5, 1, 2 and 4 µg/kg/min, each infusion step for 20 minutes	Drug: Sodium-nitroprusside intravenous infusion; 0, 0.25, 0.5, 1, 2, and 4 µg/kg/min; 20 minutes per infusion step
Placebo Comparator: 4 Physiologic saline solution	Drug: Physiologic saline solution (control substance) intravenous infusion, infusion period 120 minutes

Outcome Measures

Primary Outcome Measures

Optic disc blood flow (laser Doppler flowmetry) [in total 24x on 4 study days]

Secondary Outcome Measures

Intraocular pressure [in total 8x in 4 study days]
Choroidal blood flow (laser Doppler flowmetry) [in total 24x on 4 study days]
Fundus pulsation amplitude in the macula (laser interferometry) [in total 24x on 4 study days]
Fundus pulsation amplitude in the optic disc (laser interferometry) [in total 24x on 4 study days]
Blood pressure, pulse rate [on 4 study days]

Eligibility Criteria

Criteria

Ages Eligible for Study:

19 Years to 35 Years

Sexes Eligible for Study:

Male

Accepts Healthy Volunteers:

Yes

Inclusion Criteria:

Men aged between 19 and 35 years, nonsmokers
Body mass index between 15th and 85th percentile (Must et al. 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
History of migraine
Blood donation during the previous 3 weeks