Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Summary Thirteen men with previously untreated essential hypertension (WHO Stage I) were studied as out-patients. Oxygen consumption, heart rate, cardiac index and brachial arterial pressure were recorded at rest supine and whilst sitting position, and during steady state exercise at 50, 100 and 150 W. The subjects were then treated with penbutolol 20–80 mg/day. In 12 responding patients hemodynamic study after 1 year demonstrated that systolic, diastolic and mean arterial pressure were reduced by approximately 20% at rest and 18% during exercise. Heart rate was reduced about 24% at rest and 26% during exercise. The stroke index did not show any significant change during rest, but during exercise the post-treatment values were 8%, 13% and 18% higher than the pre-treatment values at the 50, 100 and 150 W exercise levels, the last two changes being significant. Thus, the reduction in cardiac index during exercise was less than the reduction in heart rate — about 15%, but 24% when sitting at rest. The total peripheral resistance index did not show any significant change at rest or during exercise. Dizziness or muscular fatigue occurred in 6 patients during the first two weeks of treatment. From then on no side-effects were noted. It is concluded that the hemodynamic effects of longterm treatment with penbutolol in mild to moderate hypertension largely resemble those after the majority of other beta-blockers.
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