PMID: 1100298Sep 1, 1975

Comparison of cardiac effects of timolol and propranolol

Clinical Pharmacology and Therapeutics
M R AchongR I Ogilvie

Abstract

The cardiac effects of the beta-adrenergic blocking agent, timolol, were compared to those of propranolol after intravenous administration in 6 healthy male subjects. The effects of timolol and propranolol on maximal exercise-induced tachycardia were measured. Timolol was about ten times as potent as propranolol in antagonizing exercise-induced tachycardia. Dose-response curves to intravenous infusions of isoproterenol were obtained after three doses of each beta-antagonist. Changes in myocardial contractility were assessed by cardiac systolic time intervals and were compared to the simultaneous changes in heart rate elicited by isoproterenol. For the 6 subjects, the mean potency ratios of timolol to propranolol as an antagonist of the chronotropic and inotropic effects of isoproterenol were 13.8 (+/-0.8) and 12.7 (+/-1.0), respectively. Neither timolol nor propranolol acted more selectively on beta-receptors affecting heart rate than on those influencing contractility.

References

Nov 9, 1978·European Journal of Clinical Pharmacology·T Ishizaki, K Tawara
Apr 24, 2014·Drug Development and Industrial Pharmacy·Kalle SigfridssonYudong Wang

Related Concepts

Myocardial Contraction
Antagonist Muscle Action
Myocardium
Cardiopulmonary Exercise Test
Cardiomyopathies
Propanolamines
Novodrin
Propranolol
Isoproterenol
Timolol

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