Doxazosin withdrawal and ambulatory blood pressure monitoring in normotensive subjects.

The effect of doxazosin withdrawal on normotensive subjects was examined by ambulatory blood pressure monitoring (ABPM) during twenty-four hours. Eight normotensive volunteers were treated with doxazosin for four weeks. ABPM was done the day before withdrawal and on the second and seventh days after withdrawal. The average systolic and diastolic BP were not altered by doxazosin withdrawal either on day 2 or day 7, but pulse rate (PR) decreased on day 2 and day 7. Daytime PR decreased on day 2, but both daytime and nighttime PR decreased on day 7. On withdrawal of doxazosin, the plasma norepinephrine concentration decreased and the plasma renin activity tended to decrease. Neither overshooting hypertension nor cardiovascular event was related to doxazosin withdrawal was observed. It is concluded that, in normotensive subjects, discontinuation of doxazosin may result in bradycardia without hypotension or signs of withdrawal syndrome.