Safety and efficacy of angiotensin II receptor antagonists

Comparison of Monotherapy with Irbesartan 150 mg or Amlodipine 5 mg for Treatment of Mild-to-Moderate Hypertension

Objective. The primary objective of this study was to compare the antihypertensive efficacy of the angiotensin II receptor blocker irbesartan 150 mg and the calcium channel blocker amlodipine 5 mg in the treatment of patients with seated diastolic blood pressure (DBP) 95—110 mmHg.

Design. Multicentre, randomised, double-blind, comparative pilot study.

Methods. Subjects were 18—65 years of age, with DBP 95—110 mmHg, and of non-African American origin. Following a three-week, single-blind, placebo lead-in period, 181 subjects were randomised in a 1:1 ratio to receive once-daily irbesartan 150 mg (n=89) or amlodipine 5 mg (n=92) for four weeks. Trough (24±3 hours post-dosing) BP measurements were obtained at baseline and at Weeks 2 and 4 under standardised, controlled conditions. Response was defined as DBP <90 mmHg or a reductionfrom baseline of ≥10 mmHg.

Results. After four weeks of treatment, the mean (±SE) decrease from baseline in DBP was 9.4±0.6 mmHg in the irbesartan group vs. 9.6±0.6 mmHg in the amlodipine group (p=0.806). The mean decrease from baseline in seated systolic BP was 12.2±1.0 mmHg in the irbesartan group vs. 12.0±1.0 mmHg in the amlodipine group (p=0.885). Overall, 62% of subjects in the irbesartan group and 63% in the amlodipine group had a response (p=0.609), and 54% and 56% of patients (p=0.596), respectively, had their DBP normalised (<90 mmHg). Adverse events were reported by 21.3% of patients receiving irbesartan and 20.7% receiving amlodipine.

Conclusions. Irbesartan 150 mg demonstrated comparable efficacy to amlodipine 5 mg, thereby confirming its value as an antihypertensive treatment option in non-African American patients with DBP 95—110 mmHg.

Antihypertensive activity of angiotensin II AT1 receptor antagonists: a systematic review of studies with 24 h ambulatory blood pressure monitoring

OBJECTIVE

To perform a systematic review of the antihypertensive activity of the angiotensin II AT1 receptor antagonists (ARB).

METHODS

Studies in which blood pressure (BP) was measured using ambulatory BP monitoring for at least 24 h were collected from MEDLINE. Data for each treatment group, ARB, placebo or the drug used for its comparison were obtained from the selected studies. Only studies with a minimum of quality criteria were selected. The final study group contained 36 publications, with a total of 47 patient cohorts receiving ARB in monotherapy, 10 with placebo, 10 with amlodipine, and five with enalapril. The reduction in clinical and ambulatory BP during 24 h, day, night and the last 4-h period for each of the drugs analysed were calculated and adjusted by age, sex, number of participants and by the initial BP level.

RESULTS

The global antihypertensive activity of ARB differs from that observed with amlodipine in the sense that the magnitude of the reduction in the BP values does not essentially depend on the initial BP values nor on the dose used. When only ARB were considered, the drug used was a determinant for systolic BP reduction, whereas for diastolic BP the influence was on the BP reduction and the duration of the antihypertensive activity. The dose used had a particular influence on the duration of the antihypertensive activity for both systolic and diastolic BP.

CONCLUSION

Among the ARB, the influence is on duration more than on the magnitude of BP reduction. Dose, therefore, is an important factor in the duration of antihypertensive activity.

Antihypertensive efficacy and safety of olmesartan medoxomil compared with amlodipine for mild-to-moderate hypertension

The antihypertensive efficacy of the angiotensin II receptor blocker olmesartan medoxomil has been shown to compare favourably with that of other antihypertensive agents. This randomized, double-blind study compared the antihypertensive efficacy of the starting dose of olmesartan medoxomil with that of the calcium channel blocker amlodipine besylate (amlodipine) in subjects with mild-to-moderate hypertension. Following a 4-week, single-blind, placebo run-in period, 440 subjects aged >/=18 years were randomized to the starting dose of olmesartan medoxomil (20 mg/day), amlodipine (5 mg/day), or placebo for 8 weeks. Subjects were evaluated by 24-h ambulatory blood pressure monitoring (ABPM) and by seated cuff blood pressure (BP) measurements at trough. The primary end point was the change from baseline in mean 24-h diastolic blood pressure (DBP) by ABPM at Week 8. Secondary end points included change from baseline in mean 24-h ambulatory systolic blood pressure (SBP) at 8 weeks, change from baseline in mean seated trough cuff DBP and SBP measurements, and response and control rates for DBP <90 and <85 mmHg. Control rates for SBP <140 and <130 mmHg were also calculated. Olmesartan medoxomil and amlodipine produced significantly greater reductions in ambulatory and seated DBP and SBP compared with placebo. Mean reductions in ambulatory and seated BP were similar between the two active agents; however, in the olmesartan medoxomil group, significantly more patients achieved the SBP goal of <130 mmHg and the DBP goal of <85 mmHg. Both drugs were well tolerated at the recommended starting dose. Although amlodipine was associated with a higher incidence of oedema, this did not reach statistical significance. Olmesartan medoxomil is an effective antihypertensive agent, with BP-lowering efficacy at the starting dose similar to that of amlodipine, and is associated with more patients achieving the rigorous BP goals of SBP <130 mmHg and DBP <85 mmHg.

Antihypertensive efficacy of olmesartan compared with other antihypertensive drugs

The therapeutic profile of olmesartan medoxomil, which is a recently developed angiotensin II (A II) receptor blocker, has been compared with four commonly used antihypertensive therapeutic drugs (atenolol, captopril, felodipine and losartan) in five separate multicentre, randomised, double-blind, parallel-group, phase III trials. The trials were designed to compare the efficacy of individually optimised dosages of olmesartan medoxomil and the comparator agent. The primary efficacy variable in all trials was the mean change from baseline to week 12 in trough mean sitting diastolic blood pressure (DBP). Olmesartan medoxomil (10-20 mg once daily (o.d.)) showed similar efficacy to atenolol (50-100 mg o.d.), both in patients with mild-to-moderate hypertension and, when given together with hydrochlorothiazide (HCTZ) 25 mg o.d., in patients with moderate-to-severe hypertension. Olmesartan medoxomil (20-40 mg o.d.) was also similar in efficacy to felodipine (5-10 mg o.d.) in reducing BP in patients with mild-to-moderate hypertension. Compared with captopril (12.5-50 mg twice daily (b.i.d.)) and losartan (50-100 mg o.d.), in patients with mild-to-moderate hypertension, olmesartan medoxomil (5-20 mg o.d. and 10-20 mg o.d., respectively) was significantly superior in terms of lowering DBP from baseline to week 12. In terms of the secondary efficacy variable, which was mean change from baseline to week 12 in trough mean sitting systolic BP, olmesartan showed significant superiority to atenolol, captopril and losartan in patients with mild-to-moderate hypertension. In the longer term, compared with losartan, a lower percentage of olmesartan-treated patients required concomitant HCTZ after 12 weeks of therapy. Olmesartan was well tolerated in all studies.

Discordant responses to two classes of drugs acting on the renin-angiotensin system

INTRODUCTION

Marked heterogeneity characterises blood pressure (BP)responses to antihypertensive drugs. The efficacy of drugs acting on the renin-angiotensin-aldosterone system(RAAS) is predicted (albeit weakly) by plasma renin activity (PRA) and it has been assumed that, within individuals, there would be concordance in efficacy between drugs acting at different sites to block the RAAS.

DESIGN

The present study was a randomised, double-blind,two-way, crossover study designed to evaluate intra-individual BP responses to an angiotensin II AT -receptor blocker (ARB), candesartan cilexetil, and anangiotensin-converting enzyme inhibitor (ACE-I), lisinopril, and to identify potential phenotypic characteristics of patients' responses to the drugs.

METHODS

92 patients with essential hypertension, (mean systolic/diastolic BP 160/101 mmHg) entered the trial,of whom 76 patients completed both treatments.

RESULTS

There was marked heterogeneity in response to the two drugs. 50% of patients responded (fall in diastolic BP of>10 mmHg or achieved diastolic pressure <90 mmHg)to both drugs; 16% were non-responders to both drugs; 20% responded to the ACE-I but not the ARB and 15% responded to the ARB but not to the ACE-I. Individual responses to the two drugs were poorly correlated (for diastolic pressure: r=0.19, p=0.11; for systolic pressure: r=-0.01, p=0.92). For the ACE-I, the fall in both systolic and diastolic BP was related to pre-treatment PRA (for diastolic pressure: r=0.31, p=0.008; for systolic pressure: r=0.24, p=0.04). In the case of the ARB, no relationship between the fall in BP and PRA was observed. These observations suggest that more complex mechanisms may be involved in BP reduction with ARBs than with ACE-I.

Endothelial dysfunctions: common denominators in vascular disease

The past 20 years have witnessed enormous progress in our understanding of the biology of vascular endothelium and its role in cardiovascular disease. Stemming from the seminal observations of Furchgott, the concept of a continuous regulation of vascular tone by normal endothelium and alterations of such control in disease states has become one of the most enlightening concepts of cardiovascular research. This review covers a few updates on the topic, illustrating selective areas of recent progress in our understanding of endothelial function in the control of leucocyte adhesion, atherogenesis and vascular tone, as well as the alterations that cause and accompany vascular disease.

Endothelial dysfunctions: common denominators in vascular disease

The past 20 years have witnessed enormous progress in our understanding of the biology of vascular endothelium and its role in cardiovascular disease. Stemming from the seminal observations of Furchgott, the concept of a continuous regulation of vascular tone by normal endothelium and alterations of such control in disease states has become one of the most enlightening concepts of cardiovascular research. This review covers a few updates on the topic, illustrating selective areas of recent progress in our understanding of endothelial function in the control of leucocyte adhesion, atherogenesis and vascular tone, as well as the alterations that cause and accompany vascular disease.