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Exercise increases plasma concentrations of (R)- and (S)-propranolol
K Stoschitzky1, M Schumacher, G Stark
1Institute of Pharmaceutical Chemistry, Karl Franzens University, Graz, Austria.
European Journal of Clinical Pharmacology
|January 1, 1996
Summary
Physical exercise increases plasma concentrations of both (R)- and (S)-propranolol enantiomers. The (S)-propranolol increase is linked to release from adrenergic nerves, potentially explaining variable drug efficacy.
Area of Science:
- Pharmacology
- Exercise Physiology
- Clinical Chemistry
Background:
- Previous studies showed exercise-induced increases in (S)-atenolol plasma concentrations.
- Adrenergic cells are implicated in the release of (S)-atenolol during exercise.
Purpose of the Study:
- To investigate the impact of physical exercise on plasma concentrations of (R)- and (S)-propranolol enantiomers.
- To compare exercise effects on propranolol enantiomers with previous atenolol findings.
Main Methods:
- 12 patients on chronic racemic (R, S)-propranolol treatment were studied.
- Blood samples collected pre- and post-exercise.
- Plasma concentrations of (R)- and (S)-propranolol determined using High-Performance Liquid Chromatography (HPLC).
Main Results:
- At rest, (S)-propranolol plasma concentrations were 20% higher than (R)-propranolol.
- During exercise, plasma concentrations of both (R)-propranolol (+129%) and (S)-propranolol (+109%) significantly increased.
Conclusions:
- Exercise-induced increase in (S)-propranolol plasma levels is attributed to release from adrenergic nerves.
- The mechanism for the (R)-propranolol increase during exercise requires further investigation.
- Synaptic release of (S)-propranolol may contribute to the variable correlation between plasma concentration and effect observed for beta-adrenoceptor antagonists.