PMID: 7398183Aug 1, 1980

Plasma timolol levels and systolic time intervals

Clinical Pharmacology and Therapeutics
B N SinghC Y Chew

Abstract

The beta-blocking potency of timolol was compared with that of propranolol under steady-state conditions in eight healthy subjects. The effects on systolic time intervals in healthy subjects and patients (n = 6) with coronary artery disease were evaluated in relation to varying timolol dose schedules and plasma concentrations. The beta-blocking potency was assessed by the inhibition of exercise-induced tachycardia. Timolol was eight times as potent as propranolol. There was wide between-patient variation (2.6 to 13.8) in timolol plasma concentration, and correlation between dose and peak (r = 0.61, p < 0.01) or nadir (r = 0.5 p < 0.01). There was a relatively weak correlation between timolol plasma concentration and degree of beta-blockade (r = 0.45, p < 0.05) and a linear correlation with dose (r = 0.98, p < 0.001). In healthy subjects timolol and propranolol had variable effects on systolic time intervals but in patients with coronary artery disease equipotent doses prolonged the preejection period, isovolumetric contraction time, and the ratio of the preejection period over the left ventricular ejection time. In patients as well as in normal subjects, the data indicated considerable beta-blocking effects for both drugs at th...Continue Reading

References

Feb 1, 1989·Journal of Pharmacokinetics and Biopharmaceutics·S J VetticadenT B Allison
Apr 5, 2012·Pediatric Dermatology·Matthias MoehrleRangmar Goelz

Related Concepts

Myocardial Contraction
Coronary Artery Disease
Systole
Propanolamines
Individuality
Rexigen
Dose-Response Relationship, Drug
Tachycardia
Coronary Heart Disease
Pulse Rate

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