Intravenous injection of papaverine hydrochloride in doses of 64 mg was found to increase the oxygen available to the brain in subjects suffering from acute stroke (cerebral thromboembolism) proven by arteriography. This was established by continuous measurement of cerebral arteriovenous differences for oxygen pressure and saturation. Both the latter showed significant increases. Cerebral venous carbon dioxide pressure (Pco2) decreased and cerebral venous pH increased significantly. Analysis of cerebral arteriovenous differences indicated that the increase in oxygen available to the brain was due to increased cerebral blood flow despite some decrease in arterial Pco2 due to hyperventilation. The increase in cerebral blood flow occurred even in the presence of high Pco2 values and was greater in older subjects than in younger subjects. Clinical evaluation of two groups of subjects with acute stroke (proven by arteriography) who were selected for treatment in a random manner indicated that the group of subjects who underwent treatment with papaverine improved more than those that did not receive this drug (0.01 <P<0.05).
Meyer JS, Gotoh F, Gilroy J, Nara N. Improvement in Brain Oxygenation and Clinical Improvement in Patients With Strokes Treated With Papaverine Hydrochloride. JAMA. 1965;194(9):957-961. doi:10.1001/jama.1965.03090220013003