Amlodipine and physiological responses to brisk exercise in healthy subjects

Recent studies have questioned the safety of calcium antagonists in general, and short-acting dihydropyridine derivatives in particular. Reasons include excessive catecholamine stimulation after stress. We therefore wanted to assess whether amlodipine, a second generation dihydropyridine with a prolonged plasma half-life, would show a more favourable haemodynamic and biochemical profile after strenuous exercise. For this purpose, we studied 9 healthy volunteers in a double-blind, randomized, placebo-controlled trial. After 10 days of amlodipine, 5 mg orally daily or placebo therapy, volunteers performed a treadmill effort test; the sequence was repeated after a 2-week washout period. Amlodipine caused a significant increase in mean resting heart rate (HR) (from 65 +/- 3 to 70 +/- 3 beats/min, p < 0.05), without changing systolic or diastolic blood pressure (SBP, DBP). Post-exercise haemodynamic responses were similar while on amlodipine or placebo therapy. Amlodipine did not alter the normal profile of resting or exercise-induced metabolic [plasma glucose, serum K+, serum free fatty acid (FFA)] and hormonal [plasma cortisol, growth hormone, prolactin, insulin, epinephrine (EPI) and norepinephrine (NE)] responses--although plasma EPI concentrations dropped significantly lower (p < 0.05) at 5 min and 15 min post-exercise while on the calcium antagonist. We conclude that amlodipine has a largely neutral effect on the physiological profile after brisk exercise in healthy young subjects and that this may prove to be a useful property for a vasodilator drug.