Comparative and Combined Efficacy of Doxazosin and Enalapril in Hypertensive Patients

Abstract

Twenty patients with essential hypertension were randomised to a 7-week period of dose titration with doxazosin, 1-8mg/day or enalapril, 5-20mg/day. In a further 7-week period the dosage level reached with the initial drug was halved, and titration with the second agent was carried out. Blood pressure responses at the end of each treatment period were assessed by clinic measurements made 24 hours post-dose. In the first treatment period, enalapril (mean dose 19mg/day) reduced serum free ACE activity by 40% and had a greater effect than doxazosin (mean dose 5.2mg/day) on clinic supine blood pressure (systolic and diastolic). In the second period, the addition of enalapril to doxazosin was associated with a significant fall in clinic standing blood pressure (systolic and diastolic), despite the doxazosin dose reduction and consequent decrease in median plasma doxazosin concentration (from 10.6 to 5.2ng/ml). Alternatively, when doxazosin was added to enalapril, free ACE activity remained 40% decreased despite enalapril dose reduction, and blood pressure was not further affected. Plasma renin activity was increased by enalapril. No changes were observed in plasma aldosterone or lipid concentrations with either drug. The combination of doxazosin and enalapril was well tolerated and lowered blood pressure overall. Judged by clinic measurements 24 hours post-dose, most of the antihypertensive effect was attributable to the enalapril component. However, ambulatory blood pressure monitoring 0-12 hours post-dose in a subset of patients suggested a contribution of doxazosin earlier in the dose interval.

Videoimaging of prostatic stromal-cell contraction: An in vitro model for studying drug effects

“…Its effectiveness has been demonstrated in large clinical trials [19]. We used concentrations of 10 nM-1 M, which were found to be clinically relevant plasma levels in doxazosin-treated patients [20]. The same concentrations were used in isometric tension studies and were shown to be effective in suppressing prostatic strip contractility [21].…”

Renal Hemodynamic Effects of Captopril and Doxazosin during Slight Physical Activity in Hypertensive Patients with Type-1 Diabetes mellitus

“…This is a situation where the sympathetic nervous system is activated and is also closer to daily life activities compared to examinations done in the recumbent position. Evidence for the importance of body posture in the evaluation of antihypertensive efficacy is also delivered by Stokes et al [16] who found enalapril and doxazosin equally effective in the standing position, while enalapril was more effective than doxazosin in the supine position in a group of essential hypertensive patients.…”

The Effects of Verapamil, Hydralazine, and Doxazosin on Renin, Aldosterone, and the Ratio Thereof

“…However, doxazosin's apparent aldosteronesuppressing effects would be presumably dampened by the autonomous excessive production of aldosterone that typifies PA. Thus, the study by Mulatero et al and our own could dovetail nicely in demonstrating the spectrum of the effects that doxazosin has on the two primary patient types who typically undergo PA screening, that being essential hypertensives and patients with as-yet undiagnosed PA. Of the few other studies performed regarding doxazosin, they typically focused on the effect it had on renin levels, without a thorough investigation of aldosterone or ARR changes [18][19][20]. There is some evidence that doxazosin may marginally increase renin release [21][22][23], but no notable investigations have been performed regarding the effect of doxazosin on aldosterone levels nor the ARR beyond our own and that of Mulatero and colleagues.…”