EFFECTS OF DIGOXIN AND DIGITOXIN ON CIRCADIAN BLOOD-PRESSURE PROFILE IN HEALTHY-VOLUNTEERS

Background The aim of the study was to investigate the potential effec ts of chronic digoxin or digitoxin treatment on circadian blood pressu re profile in normotensive subjects. Methods In two randomized double- blind, placebo-controlled cross-over protocols, 22 healthy normotensiv e subjects were enrolled, 12 subjects in either study. After adequate loading doses, digoxin 0.25 mg twice daily or digitoxin 0.1 mg daily w as given for a total of 10 days. Automatic 24-h ambulatory blood press ure measurements were carried out at days 4 and 10 of either glycoside or placebo. Results Digoxin treatment significantly decreased heart r ate (HR) and diastolic blood pressure (DBP) during the overnight sleep ing phase of day 10 compared with placebo (HR, 4 beats min(-1); DBP, 8 mmHg; P < 0.05). Digitoxin treatment significantly decreased heart ra te 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 no r digitoxin significantly affected systolic blood pressure. Conclusion s Both digoxin and digitoxin, within therapeutic steady-state plasma c oncentrations, reduce diastolic blood pressure and heart rate during o vernight sleep, presumably because of increased parasympathetic activi ty or decreased sympathetic activity.