Effect of Chlorpromazine on Cerebral Hemodynamics and Cerebral Oxygen Metabolism in Man

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Abstract
Nine of 13 normal control subjects received the chlorpro- mazine intravenously and 4 received it intramuscularly. Subjects were studied in the fasting state in the supine position. Measurements of pulse rate, respiratory rate and blood pressure were taken during a control period and repeatedly during the course of each of the experiments. Arterial blood pressure was measured by direct intra-arterial manometry. Cerebral blood flow was determined by the nitrous oxide method. Following the control observations, 50 mg of chlorpromazine were given. Observations on cerebral hemodynamics and cerebral O2 metabolism were again made 1 hour later. Cerebral blood flow was frequently reduced following the intravenous administration of chlorpromazine but apparently this change was a result of the associated reduction in mean arterial blood pressure, rather than a direct effect of the drug on the cerebral circulation. When the blood pressure was then elevated to normotensive levels with nor-epinephrine, the cerebral blood flow returned toward normal. Chlorpromazine did not exert a direct depressant effect on cerebral O2 consumption. When chlorpromazine was given by the intramuscular route, blood pressure was not reduced significantly and cerebral blood flow and cerebral O2 consumption were not altered. The metabolic effect of chlorpromazine is quite different irom that of morphine and barbiturates, since the latter agents depress cerebral O2 uptake without affecting cerebral blood flow.