Ocular Hemodynamic Effects of Nitrovasodilators in Healthy Subjects

Condition(s) targeted: Glaucoma

Intervention: Nitroglycerin (Drug); Isosorbide-Dinitrate (Drug); Sodium-nitroprusside (Drug); Physiologic saline solution (control substance) (Drug)

Phase: N/A

Status: Completed

Sponsored by: Medical University of Vienna

Official(s) and/or principal investigator(s):
Hans-Georg Eichler, MD, Principal Investigator, Affiliation: Department of Clinical Pharmacology, Medical University of Vienna

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.

Official title: Ocular Hemodynamic Effects of Nitrovasodilators in Healthy Subjects

Study design: Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Investigator, Outcomes Assessor), Primary Purpose: Basic Science

Primary outcome: Optic disc blood flow (laser Doppler flowmetry)

Secondary outcome:

Intraocular pressure

Choroidal blood flow (laser Doppler flowmetry)

Fundus pulsation amplitude in the macula (laser interferometry)

Fundus pulsation amplitude in the optic disc (laser interferometry)

Blood pressure, pulse rate

Minimum age: 19 Years. Maximum age: 35 Years. Gender(s): Male.

Criteria:

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

Department of Clinical Pharmacology, Medical University of Vienna, Vienna 1090, Austria

Starting date: January 1999
Last updated: December 17, 2008