Sildenafil (Viagra) Treatment of Subacute Ischemic Stroke

Stroke is the third leading cause of death and the leading cause of serious long-term disability in the United States. Approximately 15-30% of stroke survivors are permanently disabled. Twenty eight percent of stroke patients are under age 65 which results in a loss of work income. While many restorative therapies are touted as promising for the treatment of ischemic stroke, to date none are approved for this purpose. Sildenafil (Viagra®), a phosphodiesterase type 5 inhibitor, has been shown to reduce mortality and improve the functional outcomes of young and aged rats when administered 24 hours and 7 days after stroke onset. Such results are encouraging and warrant further investigation in human stroke. The specific aims of this study are to assess the safety of treating ischemic stroke patients with sildenafil (Viagra®) and to evaluate their outcomes at day 90. This will be a phase I dose-escalation study with cohort sizes of 12 patients (depending on the occurrence of serious adverse events). A total enrollment of 120 patients is planned. Patients who are between 4 and 7 days from stroke onset will receive 25, 50, 75, 100, 125, 150, 175, and 200 mg daily of sildenafil for a period of 14 days. Of the 120 patients, 24 will be randomly selected to receive standard treatment but will not receive sildenafil. All patients and physicians will be aware of treatment assignment. Evaluation of potential toxicity will be monitored throughout the course of treatment and during a formal visit at day 16 after initiation of treatment. Plasma monitoring of vascular endothelial growth factor (VEGF) will be made prior to treatment, at days 7, 16, 30, 60, and 90. Measurements of NIHSS scores, Rankin scores, and Barthel indices will be made at days 30, 60, and 90. Patients will also be assessed for color vision changes and sexual function during day 16 and day 90 visits. There will be every other day phone calls to patients while on treatment. The primary outcome measure will be death, recurrent stroke, and myocardial infarction during treatment. Exploratory analysis will include functional outcomes as measured on the neurological scales, and changes in VEGF levels in relation to clinical outcome. The long-term objective is to identify a safe and easily administered treatment that improves functional outcome in patients with ischemic stroke.