Effects of digoxin and digitoxin on circadian blood pressure profile in healthy volunteers

Background The aim of the study was to investigate the potential effects of chronic digoxin or digitoxin treatment on circadian blood pressure profile in normotensive subjects. Methods In two randomized double-blind, placebo-controlled cross-over protocols, 22 healthy normotensive subjects were enrolled, 12 subjects in either study. After adequate loading doses, digoxin 0.25 mg twice daily or digitoxin 0.1 mg daily was given for a total of 10 days. Automatic 24-h ambulatory blood pressure measurements were carried out at days 4 and 10 of either glycoside or placebo. Results Digoxin treatment significantly decreased heart rate (HR) and diastolic blood pressure (DBP) during the overnight sleeping phase of day 10 compared with placebo (HR, 4 beats min(-1); DBP, 8 mmHg; P < 0.05). Digitoxin treatment significantly decreased heart rate and diastolic blood pressure during the overnight sleeping phase of day 4 (HR, 8 beats min(-1); DBP, 7 mmHg) and day 10 (HR, 7 beats min(-1); DBP, 5 mmHg) compared with placebo (P < 0.05). Neither digoxin nor digitoxin significantly affected systolic blood pressure. Conclusions Both digoxin and digitoxin, within therapeutic steady-state plasma concentrations, reduce diastolic blood pressure and heart rate during overnight sleep, presumably because of increased parasympathetic activity or decreased sympathetic activity.