NCIt definition : A lipophilic, nonselective beta-adrenergic receptor antagonist with anti-anginal and
antihypertensive activities. Penbutolol competitively binds to and blocks beta-1 adrenergic
receptors in the heart, thereby decreasing cardiac contractility and rate. This leads
to a reduction in cardiac output and lowers blood pressure. In addition, penbutolol
prevents the release of renin, a hormone secreted by the kidneys that causes constriction
of blood vessels.;