Early and late effects of levodopa on the cardiovascular system in Parkinson's disease: A paired study

Abstract

In a group of 23 patients with idiopathic Parkinsonism under the age of 64, intra-arterial blood pressure recording was undertaken before levodopa therapy and at 4 weeks of treatment. In 7 of these patients a further series of observations was made at 6 months of treatment. The response to infused noradrenaline was examined in 11 patients. A significant reduction in resting supine mean blood pressure and in pulse rate was found at 4 weeks, but at 6 months of treatment the supine mean blood pressure had regained its original level while a reduction in pulse rate persisted. No increase in the incidence of postural hypotension occurred at 4 weeks or 6 months, nor was there any increase in the fall in mean blood pressure to tilt at these times. The index of reflex tachycardia was unimpaired but the efficiency of reflex vasoconstriction was significantly reduced at 4 weeks of treatment and persisted at 6 months. There was no change in the sensitivity to infused noradrenaline as a result of levodopa therapy. The findings are interpreted as being due to the central action of levodopa.