Treatment with irbesartan or atenolol improves endothelial function in essential hypertension

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

ADMA and oxidative stress may relate to the progression of renal disease: rationale and design of the VIVALDI study

The renin angiotensin system has been shown to be involved in the patho genesis of vascular and renal sequelae of diabetes mellitus. In type 2 diabetes mel litus, angiotensin receptor blockers have been shown to exert clinical benefit by reducing the progression of diabetic nephropathy. They also improve endothelium- mediated vascular function. The latter effect is partly due to the reduction of angiotensin II-associated oxidative stress. Moreover, small clinical studies have shown that treatment with angiotensin receptor blockers also reduces the circulating levels of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthase.

In the VIVALDI trial, the ability of the angiotensin receptor blocker telmisartan to reduce the progression of diabetic nephropathy (associated with proteinuria) in com parison with valsartan in more than 800 patients with type 2 diabetes during 1 year of treatment is being studied. In order to gain more detailed insight into the poten tial pathomechanisms associated with this effect, further end-points have been defined. Among these are the circulating levels of ADMA and the urinary excretion rate of 8-iso-prostaglandin F2α (8-iso-PGF 2α). The former is an endogenous inhibitor of NO-mediated vascular function(s) and a prospectively determined marker of major cardiovascular events and mortality; the latter is a lipid peroxidation product resulting from the nonenzymatic peroxidation of arachidonic acid, which exerts detrimental vascular effects similar to those of thromboxane A2. Urinary 8-iso-PGF 2α has been shown in clinical studies to be an independent marker of cardiovascular disease.

Highlighting the effects of telmisartan on ADMA and 8-iso-PGF levels in such a large cohort of diabetic patients will enhance our understanding of the roles of dys functional NO metabolism and redox mechanisms in the pathogenesis of end-organ damage and its prevention by pharmacotherapy with angiotensin receptor blockers.

AT1receptor antagonism in hypertension: what has been learned with irbesartan?

Irbesartan is a long-acting angiotensin II antagonist acting specifically at the level of the Type 1-receptor subtype (AT1-receptor). This compound lowers blood pressure dose-dependently in hypertensive patients and has a placebo-like tolerability. The antihypertensive efficacy of irbesartan is greatly enhanced by the coadministration of a diuretic, and fixed-dose combinations of irbesartan and hydrochlorothiazide are now available. Irbesartan-based treatment appears especially effective for high-risk patients, such as those with diabetes, renal disease and cardiac hypertrophy. In patients with Type 2 diabetes, irbesartan delays the development of nephropathy as well as the progression of renal failure. Irbesartan may have antiatherosclerotic properties beyond those expected from blood pressure lowering per se: this AT1-blocker decreases the vascular oxidative stress and prevents the procoagulant as well as the pro-inflammatory effects of angiotensin II. Irbesartan given alone or in combination with a diuretic therefore represents a rational approach to treat hypertensive patients.

Optimal therapeutic strategy for treating patients with hypertension and atherosclerosis: focus on olmesartan medoxomil

Cardiovascular (CV) disease is a major factor in mortality rates around the world and contributes to more than one-third of deaths in the US. The underlying cause of CV disease is atherosclerosis, a chronic inflammatory process that is clinically manifested as coronary artery disease, carotid artery disease, or peripheral artery disease. It has been predicted that atherosclerosis will be the primary cause of death in the world by 2020. Consequently, developing a treatment regimen that can slow or even reverse the atherosclerotic process is imperative. Atherogenesis is initiated by endothelial injury due to oxidative stress associated with CV risk factors including diabetes mellitus, hypertension, cigarette smoking, dyslipidemia, obesity, and metabolic syndrome. Since the renin– angiotensin–aldosterone system (RAAS) plays a key role in vascular inflammatory responses, hypertension treatment with RAAS-blocking agents (angiotensin-converting enzyme inhibitors [ACEIs] and angiotensin II receptor blockers [ARBs]) may slow inflammatory processes and disease progression. Reduced nitric oxide (NO) bioavailability has an important role in the process of endothelial dysfunction and hypertension. Therefore, agents that increase NO and decrease oxidative stress, such as ARBs and ACEIs, may interfere with atherosclerosis. Studies show that angiotensin II type 1 receptor antagonism with an ARB improves endothelial function and reduces atherogenesis. In patients with hypertension, the ARB olmesartan medoxomil provides effective blood pressure lowering, with inflammatory marker studies demonstrating significant RAAS suppression. Several prospective, randomized studies show vascular benefits with olmesartan medoxomil: reduced progression of coronary atherosclerosis in patients with stable angina pectoris (OLIVUS); decreased vascular inflammatory markers in patients with hypertension and micro- (pre-clinical) inflammation (EUTOPIA); improved common carotid intima-media thickness and plaque volume in patients with diagnosed atherosclerosis (MORE); and resistance vessel remodeling in patients with stage 1 hypertension (VIOS). Although CV outcomes were not assessed in these studies, the observed benefits in surrogate endpoints of disease suggest that RAAS suppression with olmesartan medoxomil may potentially have beneficial effects on CV outcomes in these patient populations.

Effects of statin treatment on endothelial function, oxidative stress and inflammation in patients with arterial hypertension and normal cholesterol levels

OBJECTIVE

Patients with arterial hypertension are characterized by impaired endothelial function and increased cardiovascular risk. Statins have been proposed as a potential treatment option in hypertension, even in those with normal low-density lipoprotein (LDL)-cholesterol levels. We tested whether fluvastatin reduces oxidative stress and inflammation, and improves endothelial function in patients with arterial hypertension and normal LDL-cholesterol.

METHODS

In a cross-over designed, double-blind randomized trial, 26 patients with arterial hypertension and LDL-cholesterol below 160 mg/dl were treated for 2 weeks with either placebo or fluvastatin 80 mg/day. Endothelium-dependent vasodilation (EDV) was assessed as the forearm blood flow (FBF) response to intra-arterial infusion of acetylcholine (ACH, 12 and 48 μg/min), and endothelium-independent vasodilation (EIV) as the FBF response to nitroprusside (3.2 and 12.8 μg/min). Furthermore, we measured reduced to oxidized glutathione (GSH/GSSG) ratio in red blood cells, total antioxidant capacity in plasma (TAC) and high-sensitivity C-reactive protein (hs-CRP) levels.

RESULTS

Fluvastatin lowered LDL-cholesterol from 118 ± 16 to 90 ± 25 mg/dl (P < 0.0001), but had no effect on blood pressure, high-density lipoprotein (HDL)-cholesterol or triglycerides. EDV and EIV were unaffected by fluvastatin treatment (e.g. increase of FBF 48 μg/min: 339 ± 285% during placebo versus 268 ± 194% during fluvastatin, n.s.). Finally, GSH/GSSG ratio, TAC and hs-CRP levels were similar between fluvastatin and placebo treatment.

CONCLUSION

Fluvastatin treatment did not improve endothelial function, oxidative stress or inflammation in patients with arterial hypertension and normal LDL-cholesterol levels. These data argue against the usefulness of statins in patients with arterial hypertension in the absence of hypercholesterolemia or other additional risk factors.

Effects of nebivolol or irbesartan in combination with hydrochlorothiazide on vascular functions in newly-diagnosed hypertensive patients: the NINFE (Nebivololo, Irbesartan Nella Funzione Endoteliale) study

BACKGROUND

Arterial hypertension affects endothelial function and arterial stiffness. The angiotensin (AT1) receptor antagonist irbesartan improves endothelial function and arterial stiffness in hypertensive patients. Nebivolol, a beta(1)-selective beta blocker, reduces systemic vascular resistance and stimulates nitric oxide release thus exerting positive effects on vascular function. However, comparative studies on the vascular effects of third generation beta-blockers and AT1 receptor blockers are lacking. Aim of this randomized, double-blind study was to test the hypothesis of non-inferiority of nebivolol to irbesartan, both in association with hydrochlorothiazide, on endothelial function, arterial stiffness and central hemodynamic parameters in patients with arterial hypertension naïve on therapy.

METHODS

Sixty-five patients were randomized to receive irbesartan/hydrochlorothiazide (150 mg/12.5 mg day) or nebivolol/hydrochlorothiazide (5mg/12.5 mg day) for 8-weeks. Endothelial function, pulse wave velocity, augmentation index, central and brachial blood pressures were measured at baseline and at the end of the study.

RESULTS

Systolic and diastolic central blood pressure, as well as brachial arterial pressure, decreased to a similar extent after both treatments. Similar changes in endothelial function between groups were detected at the end of the study. A significant reduction in pulse wave velocity, central blood pressure, and augmentation index adjusted for heart rate, was found in both the treatment groups at the end of the study, without significant differences between groups.

CONCLUSIONS

The results of this study confirm the hypothesis of non-inferiority of short-term treatment with nebivolol compared to irbesartan, both in association with hydrochlorothiazide, on endothelial function, arterial stiffness and central hemodynamic parameters in hypertensive patients naïve on therapy.

Optimal therapeutic strategy for treating patients with hypertension and atherosclerosis: focus on olmesartan medoxomil

Cardiovascular (CV) disease is a major factor in mortality rates around the world and contributes to more than one-third of deaths in the US. The underlying cause of CV disease is atherosclerosis, a chronic inflammatory process that is clinically manifested as coronary artery disease, carotid artery disease, or peripheral artery disease. It has been predicted that atherosclerosis will be the primary cause of death in the world by 2020. Consequently, developing a treatment regimen that can slow or even reverse the atherosclerotic process is imperative. Atherogenesis is initiated by endothelial injury due to oxidative stress associated with CV risk factors including diabetes mellitus, hypertension, cigarette smoking, dyslipidemia, obesity, and metabolic syndrome. Since the renin-angiotensin-aldosterone system (RAAS) plays a key role in vascular inflammatory responses, hypertension treatment with RAAS-blocking agents (angiotensin-converting enzyme inhibitors [ACEIs] and angiotensin II receptor blockers [ARBs]) may slow inflammatory processes and disease progression. Reduced nitric oxide (NO) bioavailability has an important role in the process of endothelial dysfunction and hypertension. Therefore, agents that increase NO and decrease oxidative stress, such as ARBs and ACEIs, may interfere with atherosclerosis. Studies show that angiotensin II type 1 receptor antagonism with an ARB improves endothelial function and reduces atherogenesis. In patients with hypertension, the ARB olmesartan medoxomil provides effective blood pressure lowering, with inflammatory marker studies demonstrating significant RAAS suppression. Several prospective, randomized studies show vascular benefits with olmesartan medoxomil: reduced progression of coronary atherosclerosis in patients with stable angina pectoris (OLIVUS); decreased vascular inflammatory markers in patients with hypertension and micro- (pre-clinical) inflammation (EUTOPIA); improved common carotid intima-media thickness and plaque volume in patients with diagnosed atherosclerosis (MORE); and resistance vessel remodeling in patients with stage 1 hypertension (VIOS). Although CV outcomes were not assessed in these studies, the observed benefits in surrogate endpoints of disease suggest that RAAS suppression with olmesartan medoxomil may potentially have beneficial effects on CV outcomes in these patient populations.

Metoprolol compared to carvedilol deteriorates insulin-stimulated endothelial function in patients with type 2 diabetes - a randomized study

AIM

Studies of beta blockade in patients with type 2 diabetes have shown inferiority of metoprolol treatment compared to carvedilol on indices of insulin resistance. The aim of this study was to examine the effect of metoprolol versus carvedilol on endothelial function and insulin-stimulated endothelial function in patients with type 2 diabetes.

METHOD

24 patients with type 2 diabetes were randomized to receive either 200 mg metoprolol succinate or 50 mg carvedilol daily. Endothelium-dependent vasodilation was assessed by using venous occlusion plethysmography with increasing doses of intra-arterial infusions of the agonist serotonin. Insulin-stimulated endothelial function was assessed after co-infusion of insulin for sixty minutes. Vaso-reactivity studies were done before and after the two-month treatment period.

RESULTS

Insulin-stimulated endothelial function was deteriorated after treatment with metoprolol, the percentage change in forearm blood-flow was 60.19% +/- 17.89 (at the highest serotonin dosages) before treatment and -33.80% +/- 23.38 after treatment (p = 0.007). Treatment with carvedilol did not change insulin-stimulated endothelial function. Endothelium-dependent vasodilation without insulin was not changed in either of the two treatment groups.

CONCLUSION

This study shows that vascular insulin sensitivity was preserved during treatment with carvedilol while blunted during treatment with metoprolol in patients with type 2 diabetes.

TRIAL REGISTRATION

Current Controlled Trials NCT00497003.

Endothelial function, blood pressure control, and risk modification: impact of irbesartan alone or in combination

Irbesartan, an angiotensin II type 1 receptor antagonist, is approved as monotherapy, or in combination with other drugs, for the treatment of hypertension in many countries worldwide. Data in the literature suggest that irbesartan is effective for reducing blood pressure over a 24-hour period with once-daily administration, and slows the progression of renal disease in patients with hypertension and type 2 diabetes. Furthermore, irbesartan shows a good safety and tolerability profile, compared with angiotensin II inhibitors and other angiotensin II type 1 receptor antagonists. Thus, irbesartan appears to be a useful treatment option for patients with hypertension, including those with type 2 diabetes and nephropathy. Irbesartan has an inhibitory effect on the pressor response to angiotensin II and improves arterial stiffness, vascular endothelial dysfunction, and inflammation in hypertensive patients. There has been considerable interest recently in the renoprotective effect of irbesartan, which appears to be independent of reductions in blood pressure. In particular, mounting data suggests that irbesartan improves endothelial function, oxidative stress, and inflammation in the kidneys. Recent studies have highlighted a possible role for irbesartan in improving coronary artery inflammation and vascular dysfunction. In this review we summarize and comment on the most important data available with regard to antihypertensive effect, endothelial function improvement, and cardiovascular risk reduction with irbesartan.

Drugs with blocking effects on the renin-angiotensin-aldosterone system do not improve endothelial dysfunction long-term in hypertensive patients

In essential hypertension, endothelial dysfunction has been documented many times and correlates with prognosis. The influence of the renin-angiotensin-aldosterone system (RAAS) on endothelial dysfunction has also been studied. The present study investigated the duration of the effects of RAAS-blocking drugs on endothelial function in 44 consecutive, never-treated, outpatients with mild to moderate hypertension. Patients (11 per group) received an angiotensin receptor blocker (ARB; irbesartan 300 mg/day or valsartan 160 mg/day) or an angiotensin-converting enzyme inhibitor (ACEi; fosinopril 10 mg/day or quinapril 20 mg/day). If target blood pressure (< 140/90 mmHg) was not achieved, 12.5 mg/day hydrochlorothiazide was added. Endothelial function, assessed by measuring brachial artery diameter, did not change significantly after 6 weeks, 1 year or 3 years of treatment in any group. Across all groups, endothelium-dependent and -independent vasodilation increased significantly after 6 weeks but, after 1 year, decreased below baseline and was at a similar level after 3 years; groups did not differ significantly. Both ACEi and ARB had similar effects on endothelial function; improvement occurred at the start of treatment but was not maintained. Endothelial dysfunction may be a resistant or irreversible feature of hypertension, requiring high doses of antihypertensive drugs and above-average patient compliance.

Pressure-induced vascular oxidative stress is mediated through activation of integrin-linked kinase 1/betaPIX/Rac-1 pathway

High blood pressure induces a mechanical stress on vascular walls and evokes oxidative stress and vascular dysfunction. The aim of this study was to characterize the intracellular signaling causing vascular oxidative stress in response to pressure. In carotid arteries subjected to high pressure levels, we observed not only an impaired vasorelaxation, increased superoxide production, and NADPH oxidase activity, but also a concomitant activation of Rac-1, a small G protein. Selective inhibition of Rac-1, with an adenovirus carrying a dominant-negative Rac-1 mutant, significantly reduced NADPH oxidase activity and oxidative stress and, more importantly, rescued vascular function in carotid arteries at high pressure. The analysis of molecular events associated with mechanotransduction demonstrated at high pressure levels an overexpression of integrin-linked kinase 1 and its recruitment to plasma membrane interacting with paxillin. The inhibition of integrin-linked kinase 1 by small interfering RNA impaired Rac-1 activation and rescued oxidative stress-induced vascular dysfunction in response to high pressure. Finally, we showed that betaPIX, a guanine-nucleotide exchange factor, is the intermediate molecule recruited by integrin-linked kinase 1, converging the intracellular signaling toward Rac-1-mediated oxidative vascular dysfunction during pressure overload. Our data demonstrate that biomechanical stress evoked by high blood pressure triggers an integrin-linked kinase 1/betaPIX/Rac-1 signaling, thus generating oxidative vascular dysfunction.

Irbesartan improves arterial compliance more than lisinopril

BACKGROUND

Antihypertensive agents can reduce arterial stiffness. We hypothesized that an angiotensin receptor blocker (ARB) irbesartan and an angiotensin converting enzyme inhibitor (ACEI) lisinopril improved arterial compliance.

METHODS

A randomized, double-blind, double-dummy, controlled crossover trial. Fifteen hypertensive patients, mean age 65.5 +/- 8.9 years (mean +/- SD) were given irbesartan (150 to 300 mg/day) or lisinopril (10 to 20 mg/day) for 12 weeks and then crossed over for 12 weeks. Pulse wave velocity (PWV) in the carotid-femoral (CF), carotid-radial (CR), and femoral dorsalis-pedis (FD) were measured using a Complior((R)) PWV system.

RESULTS

After 12 weeks, systolic blood pressure (SBP) decreased from 162.4 +/- 12.9 to 134.5 +/- 14.8 with irbesartan and to 145.2 +/- 25 mmHg with lisinopril. Irbesartan and lisinopril reduced PWV (CF) in the elastic arterial system from 15.1 +/- 5 to 13.3 +/- 2.6 (p < 0.005) and to 14 +/- 4.7 (p < 0.05) m/s respectively (p = 0.345). Irbesartan reduced PWV (CR) and PWV (FD), whereas lisinopril did not. The difference between treatments was significant after SBP adjustment (p = 0.037 for PWV (CR) and p < 0.001 for PWV (FD)).

CONCLUSIONS

Irbesartan improved arterial compliance in elastic and muscular arteries, whereas lisinopril improved it only in elastic arteries.

Position of fixed‐dose combinations containing an AT1‐receptor blocker and a thiazide diuretic

Treatment of hypertension remains a difficult task despite the availability of different types of medications lowering blood pressure by different mechanisms. In order to reach the target blood pressures recommended today combination therapy is required in most patients. The co-administration of two drugs with different impacts on the cardiovascular system markedly increases the antihypertensive effectiveness without altering adversely tolerability. Fixed low-dose combinations are becoming a valuable option not only as second-line, but also as first-line therapy. In this respect the co-administration of thiazide diuretic with an AT(1)-receptor blocker is particularly appealing. The diuretic-induced decrease in total body sodium activates the renin-angiotensin system, thus rendering blood pressure maintenance angiotensin II-dependent. During blockade of the renin-angiotensin system low doses of thiazides generally suffice, allowing the prevention of undesirable metabolic effects. Also, blockade of the AT(1)-receptor, particularly when angiotensin II production is enhanced in response to diuretic therapy, is expected to be beneficial, since angiotensin II seems to contribute importantly to the pathogenesis of cardiovascular and renal complications of hypertension.

Vascular and metabolic effects of angiotensin II receptor blockers

Angiotensin II receptor blockers (ARBs) are widely used in patients with hypertension, heart failure and type 2 diabetes mellitus (T2DM). Several large clinical trials have demonstrated that these agents are effective in reducing cardiovascular mortality and morbidity. These benefits are partly independent of the degree of blood pressure reduction and most likely related to ARBs' anti-inflammatory, metabolic and vascular effects. Clinical studies showed that the anti-inflammatory effect of ARBs could be related to the dosage and/or the length of the treatment. In large clinical trials, ARBs have inconsistently reduced the risk of new-onset T2DM. Among ARBs, only losartan significantly reduced serum uric acid levels. Moreover, it has been demonstrated that ARBs improve endothelial dysfunction in patients with hypertension and/or coronary artery disease (CAD), while all but one of the studies proved that these agents could usually, after 6-12 months of therapy, induce regression of vascular hypertrophy in hypertensive patients. These positive effects could be relevant to vascular protection and, together with the blood pressure reduction, constitute the background of the improved outcome observed in clinical studies on mortality and/or morbidity in hypertensive, high-risk and CAD patients. The clinical significance of the different potency of ARBs needs to be investigated further in specific and adequately powered trials.

Is the brain the essential in hypertension?

The brain is typically considered a target for late stage hypertensive disease due to the high prevalence of stroke among hypertensive patients. Research is reviewed, however, that suggests that the brain is implicated in the initiation of high blood pressure and is itself altered by early disease processes. A substantial literature establishes neural control of the vasculature and kidney as candidate etiological factors in essential hypertension. This research, largely done in animals, is now supplemented by behavioral and brain imaging studies in humans. This review suggests that the brain and vasculature may be independently and concurrently targeted by the factors inducing essential hypertension. Early stage hypertension is associated with cognitive deficits, altered cerebral blood flow support for cognitive processing, and decreased grey matter in specific cortical regions. Pharmacological reversal of hypertension is less successful in patients with premature brain aging and fails to reverse either the progression of functional or structural changes within the cerebral cortex. Furthermore, magnetic resonance imaging Blood Oxygen Level-Dependent (BOLD) responses during psychological challenge differ between normotensive individuals at risk and those not at risk for hypertension because of their exaggerated blood pressure responses to psychological challenge. Further examination of mechanisms of action and early influences of the disease on the brain are required to understand the pathophysiological mechanisms having concurrent influences on the brain and the peripheral vasculature.

Cerebrovascular support for cognitive processing in hypertensive patients is altered by blood pressure treatment

Hypertension is associated with mild decrements in cognition. In addition, regional cerebral blood flow responses during memory processing are blunted in parietal and thalamic areas among untreated hypertensive adults, who, compared with normotensive subjects, manifest greater correlation in blood flow response across task-related brain regions. Here, we test whether pharmacological treatment of hypertension normalizes regional cerebral blood flow responses and whether it does so differentially according to drug class. Treatment with lisinopril, an angiotensin-converting enzyme blocker, known to enhance vasodilative responsivity, was compared with treatment with atenolol, a beta-blocker. Untreated hypertensive volunteers (n=28) were randomly assigned and treated for 1 year. Whole brain and regional cerebral flow responses to memory processing and acutely administered acetazolamide, a vasodilator, were assessed pretreatment and posttreatment. Peripheral brachial artery dilation during reactive hyperemia was also measured. Quantitative blood flow measures showed no difference in the magnitude of regional cerebral blood flow responses pretreatment and posttreatment to either memory tasks or acetazolamide injection. Brachial artery flow-mediated dilation increased with treatment. No differences between medications were observed. In brain regions active in memory processing, however, regional cerebral blood flow responses were more highly correlated after treatment. Specificity of cerebral blood flow to different regions appears to decline with treatment of hypertension. This greater correlation among active brain regions, which is present as well in untreated hypertensive relative to normotensive volunteers, may represent compensation in the face of less region-specific responsivity in individuals with hypertension.

Effects of estradiol and the angiotensin II receptor blocker irbesartan on vascular function in postmenopausal women

OBJECTIVE

Estradiol and angiotensin receptor blockers have prominent effects on the renin-angiotensin-aldosterone system. The purpose of this study was to determine whether irbesartan, an angiotensin receptor blocker, has a greater effect on vascular function when combined with estradiol, compared with irbesartan alone, in hypertensive postmenopausal women.

DESIGN

Fifty-one women were studied while off any antihypertensive medications or hormone therapy at baseline and after randomization to one of four treatment arms for 12 weeks: (1) irbesartan and estradiol, (2) irbesartan and placebo, (3) estradiol and placebo, and (4) placebo/placebo. Estradiol and placebo arms served as control groups. Blood pressure, brachial reactivity, aldosterone, insulin, glucose, 24-hour urinary catecholamines, urinary sodium, and creatinine were measured. Fisher's exact test was used for comparison of differences in blood pressure in the treatment arms. Paired t test and analysis of variance were also performed for within- and between-group analysis.

RESULTS

A significantly larger number of women in the irbesartan and estradiol group had a decrease of 5 mm Hg or more in both systolic and diastolic blood pressures (P < 0.05) compared with irbesartan alone group. Forearm vascular reactivity was increased significantly compared with baseline (P < 0.05), and there was a significant decrease in the serum aldosterone level after treatment compared with baseline (P < 0.05) in the irbesartan and estradiol combination group. Fasting glucose and insulin, urinary sodium/creatinine ratio, and catecholamines were similar at each time point.

CONCLUSIONS

The results suggest that irbesartan and estradiol, when used in combination, may cause a greater lowering of blood pressure in postmenopausal hypertensive women. This effect may be mediated via increased vasodilation and lower aldosterone levels. These results warrant further testing in larger clinical trials.

Updated meta-analytical approach to the efficacy of antihypertensive drugs in reducing blood pressure

BACKGROUND AND OBJECTIVE

Despite advances in the treatment of hypertension, control rates continue to be suboptimal in both Europe and the US. Strategies that improve hypertension control are therefore urgently needed. This study aimed to assess the relative efficacies of various antihypertensive drugs commonly used in France in reducing systolic and diastolic blood pressure (SBP and DBP) by using a meta-analytical approach. This update of a previously published meta-analytical approach extends the number of drugs evaluated from 13 to 19.

METHODS

A total of 80 randomised, controlled trials published between 1973 and 2007 involving 10 818 patients were selected for inclusion in the meta-analytical approach. Data were examined for 19 drugs, and 16 drugs were included in the analysis: hydrochlorothiazide, indapamide sustained-release (SR), atenolol, amlodipine, lercanidipine, manidipine, enalapril, ramipril, trandolapril, candesartan cilexetil, irbesartan, losartan, olmesartan medoxomil, telmisartan, valsartan and aliskiren. Weighted average reductions in SBP and DBP over a period of 8-12 weeks were calculated for each drug from information on both the mean and the variability in BP reduction. No trials evaluating furosemide, spironolactone or cicletanine satisfied the inclusion criteria for this analysis.

RESULTS

The average weighted reductions in SBP over 8-12 weeks were most marked with diuretics, and in particular indapamide SR 1.5 mg/day (mean change from baseline -22.2mm Hg), which reduced SBP to a greater extent than any of the other drugs evaluated (at any dosage considered). Average weighted reductions in DBP were generally similar with all classes of antihypertensives and ranged from -11.4mm Hg with the beta-adrenoceptor blocker atenolol and calcium channel antagonists to -10.3mm Hg with the angiotensin II type 1 receptor antagonists.

CONCLUSION

This new analysis supports the results of the earlier investigation, in that indapamide SR 1.5 mg/day appeared to be the most effective drug for producing significant reductions in SBP within 8-12 weeks, which is an essential element in optimising cardiovascular prevention among hypertensive patients. The clinical application of these results should take into consideration all the limitations discussed in this analysis.

Endothelial effects of antihypertensive treatment: focus on irbesartan

The endothelium is characterized by a wide range of important homeostatic functions. It participates in the control of hemostasis, blood coagulation and fibrinolysis, platelet and leukocyte interactions with the vessel wall, regulation of vascular tone, and of blood pressure. Many crucial vasoactive endogenous compounds are produced by the endothelial cells to control the functions of vascular smooth muscle cells and of circulating blood cells. These complex systems determine a fine equilibrium which regulates the vascular tone. Impairments in endothelium-dependent vasodilation lead to the so called endothelial dysfunction. Endothelial dysfunction is then characterized by unbalanced concentrations of vasodilating and vasoconstricting factors, the most important being represented by nitric oxide (NO) and angiotensin II (AT II). High angiotensin-converting enzyme (ACE) activity leads to increased AT II generation, reduced NO levels with subsequent vasoconstriction. The net acute effect results in contraction of vascular smooth muscle cells and reduced lumen diameter. Furthermore, when increased ACE activity is chronically sustained, increase in growth, proliferation and differentiation of the vascular smooth muscle cells takes place; at the same time, a decrease in the anti-proliferative action by NO, a decrease in fibinolysis and an increase in platelets aggregation may be observed. AT II is then involved not only in the regulation of blood pressure, but also in vascular inflammation, permeability, smooth muscle cells remodelling, and oxidative stress which in turn lead to atherosclerosis and increased cardiovascular risk. Given the pivotal role exerted by AT II in contributing to alteration of endothelial function, treatment with ACE inhibitors or angiotensin receptor blockers (ARBs) may be of particular interest to restore a physiological activity of endothelial cells. In this view, the blockade of the renin-angiotensin system (RAS), has been shown to positively affect the endothelial function, beyond the antihypertensive action displayed by these compounds. In this review, attention has been specifically focused on an ARB, irbesartan, to examine its effects on endothelial function.

Endothelial function, arterial stiffness and lipid lowering drugs

The endothelium is a dynamic organ that plays a pivotal role in cardiovascular homeostasis. Alteration in endothelial function precedes the development of atherosclerosis and contributes to its initiation, perpetuation and clinical manifestations. It has been suggested that the assessment of endothelial function could represent a barometer of vascular health that could be used to gauge cardiovascular risk. This review summarises the various methods used to assess endothelium-dependent vasodilatation and their potential prognostic implications. In addition, the techniques used to evaluate arterial stiffness are discussed. The latter is to some extent controlled by the endothelium and has been the subject of considerable research in recent years. This paper also discusses the effects of lipid lowering treatment on both endothelial function and arterial stiffness.

ADMA and oxidative stress may relate to the progression of renal disease: rationale and design of the VIVALDI study

The renin angiotensin system has been shown to be involved in the pathogenesis of vascular and renal sequelae of diabetes mellitus. In type 2 diabetes mellitus, angiotensin receptor blockers have been shown to exert clinical benefit by reducing the progression of diabetic nephropathy. They also improve endothelium-mediated vascular function. The latter effect is partly due to the reduction of angiotensin II-associated oxidative stress. Moreover, small clinical studies have shown that treatment with angiotensin receptor blockers also reduces the circulating levels of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthase. In the VIVALDI trial, the ability of the angiotensin receptor blocker telmisartan to reduce the progression of diabetic nephropathy (associated with proteinuria) in comparison with valsartan in more than 800 patients with type 2 diabetes during 1 year of treatment is being studied. In order to gain more detailed insight into the potential pathomechanisms associated with this effect, further end-points have been defined. Among these are the circulating levels of ADMA and the urinary excretion rate of 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha). The former is an endogenous inhibitor of NO-mediated vascular function(s) and a prospectively determined marker of major cardiovascular events and mortality; the latter is a lipid peroxidation product resulting from the nonenzymatic peroxidation of arachidonic acid, which exerts detrimental vascular effects similar to those of thromboxane A2. Urinary 8-iso-PGF2alpha has been shown in clinical studies to be an independent marker of cardiovascular disease. Highlighting the effects of telmisartan on ADMA and 8-iso-PGF levels in such a large cohort of diabetic patients will enhance our understanding of the roles of dysfunctional NO metabolism and redox mechanisms in the pathogenesis of end-organ damage and its prevention by pharmacotherapy with angiotensin receptor blockers.

Systolic and diastolic hypertension impair endothelial vasodilatory function in different types of vessels in the elderly: the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study

BACKGROUND

Endothelium-dependent vasodilation (EDV) is known to be impaired in middle-aged hypertensive individuals, but less is known regarding hypertension in the elderly.

OBJECTIVE

In the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study, different techniques to evaluate EDV in resistance and conduit arteries were applied in elderly subjects and were related to the type of hypertension.

DESIGN AND METHODS

In this population-based study, 1016 subjects aged 70 years were evaluated by the invasive forearm technique with acetylcholine (EDV), brachial artery ultrasound to assess flow-mediated dilatation (FMD) and pulse wave analysis with a beta-2 receptor agonist challenge, terbutaline. Those without antihypertensive treatment were divided into three groups: normotensive individuals (n = 256), and those with isolated systolic hypertension (n = 309) or combined systolic/diastolic hypertension (n = 79).

RESULTS

Compared with normotensive individuals, EDV was reduced in those with combined systolic/diastolic hypertension only (P = 0.0019), whereas FMD was mainly reduced in those with isolated systolic hypertension (P = 0.013). Furthermore, in regression analysis, EDV was related to diastolic blood pressure only (r = -0.10, P = 0.017), whereas FMD was mainly related to systolic blood pressure (r = -0.13, P = 0.0023). The pulse wave-based method to analyse vasoreactivity was not consistently affected by hypertension.

CONCLUSIONS

In elderly subjects, systolic hypertension mainly impairs conduit artery endothelial vasodilatory function, whereas diastolic hypertension mainly induces dysfunction in resistance arteries.

Endothelial dysfunction: a multifaceted disorder (The Wiggers Award Lecture)

Endothelial cells synthesize and release various factors that regulate angiogenesis, inflammatory responses, hemostasis, as well as vascular tone and permeability. Endothelial dysfunction has been associated with a number of pathophysiological processes. Oxidative stress appears to be a common denominator underlying endothelial dysfunction in cardiovascular diseases. However, depending on the pathology, the vascular bed studied, the stimulant, and additional factors such as age, sex, salt intake, cholesterolemia, glycemia, and hyperhomocysteinemia, the mechanisms underlying the endothelial dysfunction can be markedly different. A reduced bioavailability of nitric oxide (NO), an alteration in the production of prostanoids, including prostacyclin, thromboxane A2, and/or isoprostanes, an impairment of endothelium-dependent hyperpolarization, as well as an increased release of endothelin-1, can individually or in association contribute to endothelial dysfunction. Therapeutic interventions do not necessarily restore a proper endothelial function and, when they do, may improve only part of these variables.

A meta-analytical approach to the efficacy of antihypertensive drugs in reducing blood pressure

INTRODUCTION

Hypertension constitutes a veritable public health issue. Several classes of drugs are available for the treatment of hypertension. The objective of this meta-analytical approach was to assess the efficacy of antihypertensive drugs most commonly used in France in reducing clinical SBP and DBP.

METHODS

The antihypertensive drugs selected were hydrochlorothiazide, indapamide sustained release (SR), furosemide and spironolactone for diuretics; amlodipine and lercanidipine for calcium channel antagonists; atenolol for beta-adrenoceptor antagonists (beta-blockers); enalapril and ramipril for ACE inhibitors; and candesartan cilexetil, irbesartan, losartan, and valsartan for angiotensin II receptor antagonists. The trials selected were published between 1973 and 2004, evaluated monotherapy with trial drugs as fixed-dosage or with dosage increase, and assessed blood pressure reduction between 2 and 3 months. The analysis method used was based on the calculation of the sum weighted for the trial size.

RESULTS

A total of 72 trials (comprising 9094 patients) were selected and analyzed. No trial evaluating furosemide or spironolactone satisfied the inclusion criteria for this analysis. For SBP, the reduction was more marked with diuretics, calcium channel antagonists, and ACE inhibitors. Of all the drugs studied, indapamide SR gave the greatest SBP reduction (-22.2 mm Hg). Evaluated therapeutic classes had a similar magnitude of effect on DBP, i.e. reduction between -11.4 mm Hg with beta-adrenoceptor antagonists and -10.3 mm Hg with angiotensin II type 1 receptor antagonists.

CONCLUSION

Indapamide SR 1.5 mg appeared to be the most effective drug for a significant reduction in SBP within 2-3 months, which is an essential element in optimizing cardiovascular prevention among hypertensive patients. The clinical application of these results should take into consideration all the limitations discussed in this analysis.

Impaired Capacity for Stimulated Fibrinolysis in Primary Hypertension Is Restored by Antihypertensive Therapy

The increased risk for myocardial infarction and ischemic stroke in primary hypertension suggests that the condition is associated with prothrombotic mechanisms. We have shown that patients with hypertension have an impaired capacity for acute endothelial tissue-type plasminogen activator (t-PA) release, an important local protective response to prevent formation of intravascular thrombi. The aim of the present study was to investigate whether this impairment could be restored by the lowering of blood pressure. The capacity for acute t-PA release in response to intraarterial infusion of substance P at 8 pmol/min was investigated in a perfused-forearm study in 20 hypertensive patients (12 men and 8 women). Studies were performed when patients were untreated and after 8 weeks of randomized treatment with lisinopril or felodipine that lowered blood pressure by 26/10 and 24/12 mm Hg, respectively. The t-PA release response increased significantly with treatment (ANOVA, P =0.0001), with a similar effect in the 2 treatment groups. The peak release of t-PA increased from 257 (58) to 445 (77) ng/min×L/tissue −1 ( t test, P =0.02). Also, treatment shortened the average time to peak secretion from 6.7 (1.4) to 2.7 (0.3) min ( t test, P =0.01). In 6 patients with a delayed secretory peak (9 minutes or later), treatment normalized the response (χ 2 test, P =0.008). Antihypertensive therapy restores the capacity for acute t-PA release and improves the rapidity of the response in patients with primary hypertension. Similar responses with the 2 regimens suggest that the improvement is related to the blood pressure reduction as such. This effect may contribute to the thromboprotective effect of antihypertensive treatment.

Mean arterial pressure and systolic blood pressure for detection of hypotension during hemapheresis: implications for patients with baseline hypertension

Mean arterial pressure (MAP) has been characterized as a more sensitive and physiologically appropriate hemodynamic parameter in the detection of hemapheresis-related hypotension, resulting in a much closer correlation with the presence of symptomatic hypotension. Patients were enrolled over a 12-month period and data collected on any previous diagnosis of hypertension, antihypertensive therapy used, indication for apheresis, age decile, and gender. Baseline vital signs, any hypotensive signs or symptoms observed, and the patient's vital signs at the time of any hypotensive episode were recorded. Patients were assigned to a subgroup, sensitivity and specificity analysis performed, positive likelihood ratios calculated, receiver operating characteristic curves constructed, and ideal cutoff values identified. The incidence of hypotension among our study population was found to be 6.8%. Over all procedures, systolic blood pressure (SBP) was determined to be a "poor" test for detecting hypotension, while MAP demonstrated a "fair" capacity. A downward normalization was evident in the ideal cutoff value based upon a patient's hypertensive history. The currently accepted SBP less than 80 mmHg cutoff failed to detect hypotensive episodes among baseline hypertensive patients, raising questions about its sensitivity. Based upon physiologic principles and study findings, a MAP-based criterion is preferable in the diagnosis of hypotension during hemapheresis.

Effects of Angiotensin II Receptor Blockade with Valsartan on Pro-Inflammatory Cytokines in Patients with Essential Hypertension

Chronic inflammation is common in hypertension and acts as an independent determinant of arterial blood pressure. Hypertensive patients are reported to have high circulating levels of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and C-reactive protein (CRP). Recently, angiotensin II receptor blockers (ARBs) have been shown to possess benefits in addition to their ability to lower blood pressure, including anti-inflammatory and antioxidative properties within the vasculature. We evaluated the effects of the angiotensin II receptor blocker, valsartan, on these inflammatory cytokines. Thirty-nine patients with essential hypertension participated. These subjects received valsartan, 40 to 80 mg/day. Serum TNF-alpha, IL-6, CRP, and serum amyloid A (SAA) were measured before and after 3 months of treatment with valsartan. Valsartan significantly decreased systolic and diastolic blood pressure (160 +/- 16/92 +/- 11 mm Hg to 147 +/- 21/84 +/- 11 mm Hg, P = 0.001/P = 0.001, respectively). Serum TNF-alpha (9.1 +/- 8.6 pg/mL to 6.1 +/- 1.0 pg/mL, P = 0.006) and IL-6 (9.3 +/- 1.7 pg/mL to 8.9 +/- 1.4 pg/mL, P = 0.005) were significantly reduced after treatment with valsartan. However, C-reactive protein and serum amyloid A did not change. The angiotensin II receptor blocker, valsartan, may inhibit the development of atherosclerosis by lowering serum pro-inflammatory cytokines.

Endothelial function and its assessment

Endothelial dysfunction is a characteristic aspect of most of the conditions associated with atherosclerosis and is commonly found as an early feature in atherothrombotic vascular disease. An appreciation of the underlying mechanisms of endothelial function, as well as dysfunction, is essential as this has critical influence on the different methods in the assessment of endothelial function and effects of various treatments on its quantification. Furthermore, endothelial dysfunction is recognised as a type of 'target organ damage' in common cardiovascular conditions (e.g., hypertension) and the area is of increasing interest for new drug development, as therapies that modulate the endothelium will have added advantages; thus, for the development of new/experimental drugs, an awareness of ways to assess the endothelium is necessary. In this review, an overview of different methods including biochemical markers, and invasive and non-invasive tools, to determine endothelial function is presented as well as their clinical relevance. Furthermore, the effects of various treatments on endothelial dysfunction and their underlying mechanisms are elucidated.

Single nucleotide polymorphisms in the apolipoprotein B and low density lipoprotein receptor genes affect response to antihypertensive treatment

BACKGROUND

Dyslipidemia has been associated with hypertension. The present study explored if polymorphisms in genes encoding proteins in lipid metabolism could be used as predictors for the individual response to antihypertensive treatment.

METHODS

Ten single nucleotide polymorphisms (SNP) in genes related to lipid metabolism were analysed by a microarray based minisequencing system in DNA samples from ninety-seven hypertensive subjects randomised to treatment with either 150 mg of the angiotensin II type 1 receptor blocker irbesartan or 50 mg of the beta1-adrenergic receptor blocker atenolol for twelve weeks.

RESULTS

The reduction in blood pressure was similar in both treatment groups. The SNP C711T in the apolipoprotein B gene was associated with the blood pressure response to irbesartan with an average reduction of 19 mmHg in the individuals carrying the C-allele, but not to atenolol. The C16730T polymorphism in the low density lipoprotein receptor gene predicted the change in systolic blood pressure in the atenolol group with an average reduction of 14 mmHg in the individuals carrying the C-allele.

CONCLUSIONS

Polymorphisms in genes encoding proteins in the lipid metabolism are associated with the response to antihypertensive treatment in a drug specific pattern. These results highlight the potential use of pharmacogenetics as a guide for individualised antihypertensive treatment, and also the role of lipids in blood pressure control.

Potential mechanisms of impaired endothelial function in arterial hypertension and hypercholesterolemia

This review focuses on the role of impaired endothelial function for the development of atherosclerosis in human arterial hypertension and hypercholesterolemia in vivo. Potential mechanisms underlying impaired endothelial function and decreased bioavailability of nitric oxide under these clinical conditions are discussed. It further addresses therapeutic strategies aimed at improving the bioavailability of nitric oxide in these patients. The overall conclusion is that the bioavailability of nitric oxide is probably impaired, not by a single defect, but by various mechanisms affecting nitric oxide synthesis as well as nitric oxide breakdown. In both diseases increased superoxide anion production and oxidative stress represent a major mechanism. Decreased bioavailability of nitric oxide not only impairs endothelium-dependent vasodilation, but also activates other mechanisms that play an important role in the pathogenesis of atherosclerosis. Thus, therapeutic strategies should aim to restore bioavailability of nitric oxide, which has been demonstrated for lipid-lowering therapy in hypercholesterolemia and blood pressure control in hypertension. In addition, antioxidative strategies will represent a major therapeutic tool against atherosclerotic diseases in the future. Statins and blockers of the renin-angiotensin system seem to have such antioxidative effects independent from their effects on lipid profiles or blood pressure control.

Angiotensin AT-1 receptor antagonism: complementary or alternative to ACE inhibition in cardiovascular and renal disease?

Both angiotensin-converting enzyme (ACE) inhibitors and AT-1 receptor antagonists reduce the effects of angiotensin II, however they may have different clinical effects. This is because the ACE inhibitors, but not the AT-1 receptor antagonists, increase the levels of substance P, bradykinin and tissue plasminogen activator. The AT-1 receptor antagonists, but not the ACE inhibitors, are capable of inhibiting the effects of angiotensin II produced by enzymes other than ACE. On the basis of the present clinical trial evidence, AT-1 receptor antagonists, rather than the ACE inhibitors, should be used to treat hypertension associated with left ventricular (LV) hypertrophy. Both groups of drugs are useful when hypertension is not complicated by LV hypertrophy, and in diabetes. In the treatment of diabetes with or without hypertension, there is good clinical support for the use of either an ACE inhibitor or an AT-1 receptor antagonist. ACE inhibitors are recommended in the treatment of renal disease that is not associated with diabetes, after myocardial infarction when left ventricular dysfunction is present, and in heart failure. As the incidence of cough is much lower with the AT-1 receptor antagonists, these can be substituted for ACE inhibitors in patients with hypertension or heart failure who have persistent cough. Preliminary studies suggest that combining an AT-1 receptor antagonist with an ACE inhibitor may be more effective than an ACE inhibitor alone in the treatment of hypertension, diabetes with hypertension, renal disease without diabetes and heart failure. However, further trials are required before combination therapy can be recommended in these conditions.

Vascular and cardiac benefits of angiotensin receptor blockers

Angiotensin II not only is a vasoconstrictor, but it also affects cell growth and apoptosis, inflammation, fibrosis, and coagulation. Blockade of the renin-angiotensin system, either with inhibitors of the generation of angiotensin (angiotensin-converting enzyme [ACE] inhibitors) or with blockers of angiotensin receptors, reduces blood pressure and inhibits other pathophysiological actions. These other effects provide benefits in coronary heart disease, heart failure, diabetic nephropathy, and stroke beyond blood pressure reduction. These benefits were first demonstrated with ACE inhibitors. However, the mechanism of action of angiotensin receptor blockers, which block angiotensin II stimulation at the angiotensin type 1 receptor but not at the type 2 receptor, may have advantages, particularly for endothelial dysfunction and vascular remodeling, as well as cardiac and renal protection. Recent multicenter trials suggest that ACE inhibitors and angiotensin receptor blockers may reduce morbidity and mortality associated with cardiovascular and renal disease beyond blood pressure reduction. Several studies with different angiotensin receptor blockers, including comparisons with ACE inhibitors, are under way, and should provide further guidance for their clinical use.

Angiotensin II type 1 receptor antagonism improves hypercholesterolemia-associated endothelial dysfunction

OBJECTIVE

Hypercholesterolemia-induced angiotensin II type 1 (AT1) receptor overexpression is thought to be a key event in the development of endothelial dysfunction.

METHODS AND RESULTS

The effect of a 6-week treatment with the AT1 receptor antagonist candesartan (16 mg/d) on endothelial function and serum inflammation markers was compared with the effect of treatment with placebo or the calcium channel antagonist felodipine (5 mg/d) in 47 hypercholesterolemic patients (low density lipoprotein cholesterol >160 mg/dL). Endothelial function was assessed by measurement of forearm blood flow (FBF) by venous occlusion plethysmography. FBF during reactive hyperemia was significantly improved by candesartan, whereas felodipine and placebo exerted no effect. Nitroglycerin-induced vasorelaxation and basal FBF were not altered significantly. Blood pressure and cholesterol levels were not affected significantly by any drug. Serum concentrations of 8-isoprostane, monocyte chemoattractant protein-1, and soluble intercellular adhesion molecule-1 were significantly reduced by candesartan treatment but not by placebo or felodipine (ELISA assays). Levels of high-sensitivity C-reactive protein and tumor necrosis factor-alpha were not altered significantly by any treatment.

CONCLUSIONS

These data suggest that AT1 receptor antagonism improves endothelial function during hypercholesterolemia and that this applies not only to endothelium-dependent vasodilatation but also to oxidative stress and events involved in monocyte attraction and adhesion. AT1 receptor blockade may potentially represent a novel approach for the prevention of vascular dysfunction associated with hypercholesterolemia that is independent of lipid-lowering and blood pressure-lowering interventions.