Unpredicted Lack of Effect of Exercise on Plasma Concentrations of Carvedilol

In vitro studies have shown that β-blockers are taken up into and released from adrenergic cells together with epinephrine and norepinephrine. Consequently, studies in humans revealed an increase in plasma concentrations of propranolol and atenolol during physical exercise. However, carvedilol has not been investigated in a similar fashion. Eleven hypertensive patients on long-term treatment (4 months) with carvedilol followed an exercise regimen. Plasma concentrations of carvedilol were determined at rest (9.7 ± 3.4 ng/ml), during exercise (9.0 ± 3.2 ng/ml), and after 15 min of recovery (9.1 ± 2.7 ng/ml). Contrary to predictions, exercise had no effect on plasma concentrations of carvedilol, a finding that is in contrast to other β-blockers. We conclude that carvedilol is not taken up into and released from adrenergic nerves during exercise, a feature that clearly distinguishes carvedilol from all other β-adrenergic antagonists so far investigated.