Changes of Nocturnal Blood Pressure Dipping Status in Hypertensives by Nighttime Dosing of α-Adrenergic Blocker, Doxazosin

Abstract

Abstract-Abnormal nocturnal blood pressure (BP) dipping status may be partly determined by nocturnal sympathetic activity. We studied the effect of nighttime dosing of an ␣ 1 -adrenergic blocker, doxazosin, on the BP dipping status of 118 hypertensives, all of whom underwent 24-hour ambulatory BP monitoring before and after treatment. The mean nighttime/daytime ratio of systolic BP was increased (0.91 after therapy versus 0.89 at baseline, PϽ0.05). The patients were initially divided into 4 groups on the basis of their dipping status at the baseline assessment: 18 (15%) were extreme dippers, with a nighttime systolic BP fall of at least 20% of daytime BP; 46 (39%) were dippers (fall between 10% and 20%); 48 (41%) were nondippers (fall between 0% and 10%); and 6 (5%) were risers (nocturnal increase of systolic BP). A shift in dipping status toward less nocturnal BP dipping was observed after doxazosin therapy (PϽ0.05). Dipping status was determined by nighttime more than by daytime BP, and this was not explained by differences in the number of daytime and nighttime readings. The effects of doxazosin on the mean nocturnal systolic BP changes were an increase of 4.3 mm Hg in extreme dippers and decreases of 0.7 mm Hg in dippers, 12 mm Hg in nondippers, and 18 mm Hg in risers; the reduction was only significant in the latter 2 groups (both PϽ0.01). To estimate the effects of regression to the mean on the changes in dipping status, we also defined dipping status with the average of the BPs before and after doxazosin and found no difference in the degree of nighttime BP reduction among each group. The reduction of daytime BP was now significantly greater in the subgroups with less dipping: 6.4 mm Hg for extreme dippers and 16 mm Hg for risers (PϽ0.05). In conclusion, nighttime dosing with doxazosin markedly affects the nocturnal BP dipping status of hypertensives, but the apparently greater reduction in nighttime pressure in nondippers and risers may be, at least partly, due to the effect of regression to the mean. The most important determinants of the effect of doxazosin were the absolute BP levels, both day and night, rather than dipping status per se. (Hypertension. 2000;35:787-794.) Key word: blood pressure monitoring Ⅲ adrenergic receptor blocking Ⅲ circadian rhythm Ⅲ prospective studies

Ambulatory pulse pressure, decreased nocturnal blood pressure reduction and progression of nephropathy in type 2 diabetic patients

“…However, it is as yet unknown whether this narrowing of PP induced by dual blockade of the renin-angiotensin system will translate into a long-term reduction in microvascular complications. Several researchers have demonstrated that it is possible to restore the normal circadian BP pattern in 'non-dipper's with selective antihypertensive therapy directed towards an elevated night BP [37][38][39][40]. Interestingly, this approach has been reported to reduce 24 h albumin excretion rate in microalbuminuric patients with essential hypertension, thus suggesting an increased organoprotective effect of reestablishing the normal diurnal BP rhythm [39].…”

Nocturnal blood pressure and cardiovascular disease: a review of recent advances

“…We previously reported that nighttime dosing with an a-blocker, doxazosin, markedly reduced nocturnal BP in nondippers and reverse dippers in uncomplicated hypertensive patients. 50 Recently, the dramatic usefulness of new strategies to manipulate autonomic function, such as baroreflex activation therapy or renal denervation in resistant hypertension, has been reported. 51,52 New frontiers in the treatment of hypertension are therefore promising in terms of their potential for improving diurnal BP variation.…”

Autonomic nervous system activity is independently associated with the risk of shift in the non-dipper blood pressure pattern

“…6,7 A possible explanation of the nocturnal decrease in BP is that it results from a reduction of sympathetic nervous activity and impaired circadian rhythm in sympatho-vagal balance during sleep. 8,9 We aimed to assess whether ANS activity indices and their changes over 2 years, as evaluated by 24-h HRV, were associated with a shift to non-dipper status among subjects identified as dippers at study entry in a general elderly population not treated for hypertension.…”