Effect of oral papaverine on cerebral blood flow in normals: evaluation by the xenon-133 inhalation method.

Several issues related to the use of vasoactive drugs in the treatment of neuropsychiatric disorders secondary to cerebrovascular insufficiency remain unresolved due to lack of a practical method for the quantitative measurement of cerebral blood flow (CBF). The present report concerns the use of a noninvasive CBF method in the evaluation of a commonly used vasoactive drug (oral papaverine). Series CBF measurements were made by the Xe133 inhalation method in 21 healthy young adults, using a double-blind crossover experimental design. The findings show that oral papaverine (300 mg b.i.d.) significantly increases blood flow under conditions of both normal breathing and hyperventilation, the latter being used to induce cerebral vasoconstriction. There were large variations in individual response to the drug, and the average increase in CBF (6 to 9%) was smaller than that observed by other investigators using intravenous papaverine. No adverse reactions or alterations in blood pressure were encountered.