Source:http://linkedlifedata.com/resource/umls/id/C0282292
NCI: The sulfate salt form of penbutolol, 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, bisoprolol prevents the release of renin, a hormone secreted by the kidneys that causes constriction of blood vessels.