Abstract
Objective: We recently reported a highly stereoselective increase in plasma concentrations of (S)-atenolol during exercise which is most likely due to a release of the drug from adrenergic cells. The objective of the present study was to investigate the influence of physical exercise on plasma concentrations of the (R)- and (S)-enantiomers of propranolol.
Methods:
Blood samples were taken immediately before and at the end of exercise in 12 patients receiving chronic treatment with racemic (R, S)-propranolol. Plasma concentrations of (R)- and (S)-propranolol were determined by HPLC.
Results:
In contrast to atenolol, mean plasma concentrations of (S)-propranolol were significantly higher (+20%) than those of (R)-propranolol at rest. During exercise there was an increase in plasma concentrations of both (R)-propranolol (+129%) and (S)-propranolol (+109%).
Conclusion:
Based on information from in vitro studies we conclude that the increase in plasma concentrations of (S)-propranolol during exercise is caused by a release of the drug from adrenergic nerves, whereas the reason for the increase in (R)-propranolol remains to be determined. This release of the β-adrenoceptor blocking (S)-enantiomer directly at the synaptic gaps might be one reason for the poor correlation between plasma concentration and effect of β-adrenoceptor antagonists repeatedly described in the literature.
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Received: 28 February 1995/Accepted in revised form: 20 November 1995
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Stoschitzky, K., Schumacher, M., Stark, G. et al. Exercise increases plasma concentrations of (R)- and (S)-propranolol. E J Clin Pharmacol 50, 339–342 (1996). https://doi.org/10.1007/s002280050119
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DOI: https://doi.org/10.1007/s002280050119