Racemic (R,S)-propranolol versus half-dosed optically pure (S)-propranolol in humans at steady state: Hemodynamic effects, plasma concentrations, and influence on thyroid hormone levels (original) (raw)

Clinical pharmacology and therapeutics, 1992

Abstract

In a randomized, double-blind, crossover study in 10 healthy volunteers the hemodynamic effects, drug plasma concentrations, and thyroid hormone profiles were compared after oral administration for 1 week of 40 mg t.i.d. racemic (R,S)-propranolol versus 20 mg t.i.d. optically pure (S)-propranolol. During exercise, both substances decreased heart rate (-14%, p less than 0.01), as well as the overall rate pressure product (-19%, p less than 0.01) to the same extent, indicating similar beta-blocking effects. After oral application of (R,S)-propranolol the maximal plasma concentration (Cmax) and the area under the plasma concentration-time curve (AUC) of (S)-propranolol were higher than those of (R)-propranolol (eudismic ratios (S)- over (R)-propranolol Cmax, 1.36 [p less than 0.01] and AUC, 1.42 [p less than 0.01]) despite dose-equivalence of both enantiomers in the administered racemic (R,S)-propranolol preparation indicating different pharmacokinetic properties. Mean values of Cmax a...

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