Effect of angiotensin receptor blockade on insulin sensitivity and endothelial function in abdominally obese hypertensive patients with impaired fasting glucose.

AngII (angiotensin II) may contribute to cardiovascular risk in obesity via adverse effects on insulin sensitivity and endothelial function. In the present study, we examined the effects of ARB (angiotensin receptor blocker) therapy (losartan, 100 mg/day) on insulin sensitivity and endothelial function in 53 subjects with stage I hypertension, abdominal obesity and impaired fasting glucose. The study design was a randomized double-blinded parallel design placebo-controlled multi-centre trial of 8 weeks duration. We used the hyperinsulinaemic-euglycaemic clamp technique to measure insulin sensitivity (expressed as the 'M/I' value) and RH-PAT (reactive hyperaemia-peripheral arterial tonometry) to measure endothelial function. Additional measures included HOMA (homoeostasis model assessment)-B, an index of pancreatic ß-cell function, and markers of inflammation [e.g. CRP (C-reactive protein)] and oxidative stress (e.g. F2-isoprostanes). ARB therapy did not alter insulin sensitivity [5.2 (2.7) pre-treatment and 4.6 (1.6) post-treatment] compared with placebo therapy [6.1 (2.9) pre-treatment and 5.3 (2.7) post-treatment; P value not significant], but did improve the HOMA-B compared with placebo therapy (P=0.05). ARB therapy also did not change endothelial function [RH-PAT, 2.15 (0.7) pre-treatment and 2.11 (0.7) post-treatment] compared with placebo therapy [RH-PAT, 1.81 (0.5) pre-treatment and 1.76 (0.7) post-treatment; P value not significant]. Markers of inflammation and oxidative stress were not significantly changed by ARB therapy. In conclusion, ARB therapy did not alter peripheral insulin sensitivity or endothelial function in this cohort of patients with essential hypertension, abdominal obesity and impaired fasting glucose, but did improve pancreatic ß-cell function.

Clinical role of direct renin inhibition in hypertension.

Treatment strategies to improve blood pressure control, reduce end-organ damage, and improve cardiovascular outcomes are more important today than ever before. Most patients will require combination therapy to achieve target blood pressure; early initiation of combination therapy may help patients achieve blood pressure control more rapidly. Low-dose combinations may be more effective with fewer adverse effects than higher doses of single agents. Dysregulation of the renin-angiotensin-aldosterone system (RAAS) is an important contributor in the pathogenesis of hypertension and its sequelae. Treatment with a direct renin inhibitor blocks the rate-limiting step in the RAAS, resulting in decreased angiotensin I and II production and decreased urinary aldosterone excretion. Like the angiotensin converting enzyme inhibitors and angiotensin II receptor blockers, treatment with a direct renin inhibitor increases plasma renin concentration, but unlike the other RAAS inhibitors, treatment with a direct renin inhibitor decreases plasma renin activity. This unique combination of effects on the RAAS make a direct renin inhibitor an attractive option to combine with other antihypertensive agents for the management of hypertension and its comorbidities. Clinical studies have shown that combining the direct renin inhibitor, aliskiren, with drugs representing each of the major classes of antihypertensive agents (thiazide diuretics, beta blockers, angiotensin converting enzyme inhibitors, angiotensin II receptor blockers, and calcium-channel blockers) reduces blood pressure, improves markers for cardiovascular outcomes, or does both. Results of several ongoing randomized clinical trials should provide additional insights into the potential of therapeutic combinations that include aliskiren to improve cardiovascular morbidity and mortality in patients with hypertension and related comorbidities.

The role of baseline blood pressure in guiding treatment choice: a secondary analysis of the use of valsartan/hydrochlorothiazide as initial therapy in hypertensive adults in a randomized, double-blind, placebo-controlled trial.

BACKGROUND AND OBJECTIVE: Baseline blood pressure (BP) is a strong predictor of response to antihypertensive therapy and the patient's ability to reach BP goals. The objective of this study was to evaluate the role of baseline BP as a determinant of systolic BP (SBP) and treatment outcome to assist in the choice of initial therapy. METHODS: This was a double-blind, placebo-controlled clinical trial (n = 1329) in patients with essential hypertension (mean sitting diastolic BP [DBP] > or = 95 mmHg and <110 mmHg) who were randomized to placebo, valsartan 160 mg, valsartan 320 mg, hydrochlorothiazide (HCTZ) 12.5 mg, HCTZ 25 mg, valsartan/HCTZ 160 mg/12.5 mg, valsartan/HCTZ 320 mg/12.5 mg or valsartan/HCTZ 320 mg/25 mg. Retrospective analyses were performed to determine mean BP at end of study and BP goal rates and to explore the relationship between baseline BP level and predicted final BP. RESULTS: The final SBP and DBP were lowest in the combination therapy groups across all baseline BPs and in subgroups of patients categorized by age (> or = 65 years, <65 years), race/ethnicity (White, Black, other), and severity of hypertension at baseline. The proportion of patients achieving the SBP goal of <140 mmHg was highest in the valsartan/HCTZ 320 mg/25 mg group; the overall SBP goal achievement rate was 85%, and 78% of participants with stage 2 hypertension achieved goal. By comparison, 59% of patients in the HCTZ 25 mg group and 52% in the valsartan 320 mg group achieved SBP goal. Initial combination therapy was associated with lower predicted final SBP and DBP at all baseline BP levels compared with monotherapy. Analysis of tolerability data revealed that the proportion of patients experiencing dizziness or discontinuing therapy due to adverse events was generally similar across treatment groups, whereas the BP-lowering efficacy was greatest in the groups receiving combination therapy. CONCLUSION: These secondary analyses suggest that characterizing the relationship between baseline SBP and achieved SBP can assist in the choice of initial therapy in a broad hypertensive population. Initial therapy with the combination of valsartan/HCTZ is more effective than monotherapy in lowering BP at all baseline BP levels, is consistent in this respect among all subgroups, and is well tolerated.

Aliskiren, an orally effective renin inhibitor, provides antihypertensive efficacy alone and in combination with valsartan.

BACKGROUND: By blocking the renin-angiotensin-aldosterone system (RAAS) at its rate-limiting step, renin inhibition may provide improved RAAS suppression. We investigated the blood pressure (BP)-lowering effects of the oral direct renin inhibitor aliskiren, alone or in combination with the angiotensin receptor blocker valsartan. METHODS: In this multicenter, randomized, placebo-controlled, 8-week trial, 1123 patients with mild-to-moderate hypertension underwent a 3 to 4 week single-blind placebo run-in and were then randomized in a modified factorial study design to receive once-daily, double-blind oral treatment with placebo, aliskiren monotherapy (75, 150, or 300 mg), valsartan monotherapy (80, 160, or 320 mg), aliskiren and valsartan in combination, or valsartan/hydrochlorothiazide (160/12.5 mg). The primary efficacy variable was the change from baseline in mean sitting diastolic BP (DBP) at endpoint. RESULTS: Once-daily oral treatment with aliskiren 300 mg significantly (P < .0001) lowered mean sitting DBP and systolic BP (SBP) compared with placebo; aliskiren monotherapy demonstrated a safety and tolerability profile comparable to placebo. Changes in DBP and SBP were fitted to a first-order dose-response surface (lack-of-fit test, P = .65), which showed that aliskiren and valsartan alone and in combination produced dose-related reductions in DBP and SBP. Coadministration of aliskiren and valsartan produced a greater antihypertensive effect than either drug alone, comparable in magnitude to the effect of valsartan/hydrochlorothiazide, with similar tolerability to the component monotherapies and to placebo. CONCLUSIONS: Aliskiren monotherapy provides antihypertensive efficacy and placebo-like tolerability in patients with hypertension. Aliskiren and valsartan in combination may provide additive BP-lowering effects with maintained tolerability.

Comparison of valsartan/hydrochlorothiazide combination therapy at doses up to 320/25 mg versus monotherapy: a double-blind, placebo-controlled study followed by long-term combination therapy in hypertensive adults.

BACKGROUND: One third of patients treated for hypertension attain adequate blood pressure (BP) control, and multidrug regimens are often required. Given the lifelong nature of hypertension, there is a need to evaluate the long-term efficacy and tolerability of higher doses of combination anti-hypertensive therapies. OBJECTIVE: This study investigated the efficacy and tolerability of valsartan (VAL) or hydrochlorothiazide (HCTZ)-monotherapy and higher-dose combinations in patients with essential hypertension. METHODS: The first part of this study was an 8-week, multicenter, randomized, double-blind, placebo controlled, parallel-group trial. Patients with essential hypertension (mean sitting diastolic BP [MSDBP], > or =95 mm Hg and <110 mm Hg) were randomized to 1 of 8 treatment groups: VAL 160 or 320 mg; HCTZ 12.5 or 25 mg; VAL/HCTZ 160/12.5, 320/12.5, or 320/25 mg; or placebo. Mean changes in MSDBP and mean sitting systolic BP (MSSBP) were analyzed at the 8-week core study end point. VAL/HCTZ 320/12.5 and 320/25 mg were further investigated in a 54-week, open-label extension. Response was defined as MSDBP <90 mm Hg or a > or =10 mm Hg decrease compared to baseline. Control was defined as MSDBP <90 mm Hg compared with baseline. Tolerability was assessed by monitoring adverse events at randomization and all subsequent study visits and regular evaluation of hematology and blood chemistry. RESULTS: A total of 1346 patients were randomized into the 8-week core study (734 men, 612 women; 924 white, 291 black, 23 Asian, 108 other; mean age, 52.7 years; mean weight, 92.6 kg). All active treatments were associated with significantly reduced MSSBP and MSDBP during the core 8-week study, with each monotherapy significantly contributing to the overall effect of combination therapy (VAL and HCTZ, P < 0.001). Each combination was associated with significantly greater reductions in MSSBP and MSDBP compared with the monotherapies and placebo (all, P < 0.001). The mean reduction in MSSBP/MSDBP with VAL/HCTZ 320/25 mg was 24.7/16.6 mm Hg, compared with 5.9/7.0 mm Hg with placebo. The reduction in MSSBP was significantly greater with VAL/HCTZ 320/25 mg compared with VAL/HCTZ 160/12.5 mg (P < 0.002). Rates of response and BP control were significantly higher in the groups that received combination treatment compared with those that received monotherapy. The incidence of hypokalemia was lower with VAL/HCTZ combinations (1.8%-6.1%) than with HCTZ monotherapies (7.1%-13.3%). The majority of adverse events in the core study were of mild to moderate severity. The efficacy and tolerability of VAL/HCTZ combinations were maintained during the extension (797 patients). CONCLUSIONS: In this study population, combination therapies with VAL/HCTZ were associated with significantly greater BP reductions compared with either monotherapy, were well tolerated, and were associated with less hypokalemia than HCTZ alone.

Direct renin inhibition: focus on aliskiren.

BACKGROUND: Despite the availability of many effective, well-tolerated drugs, a significant proportion of treated hypertensive patients still have uncontrolled high blood pressure (BP) and thus face serious morbidity and mortality. The renin-angiotensin aldosterone system (RAAS) is a key target for BP control and for cardiovascular and renal protection. Renin controls the rate-limiting step in the RAAS cascade and hence is the optimal target for RAAS suppression. Aliskiren is the first direct renin inhibitor (DRI) to be approved by the U.S. Food and Drug Administration and the European Medicines Agency for treating hypertension. OBJECTIVE: To provide an overview of the pharmacology, pharmacokinetics, preclinical, and clinical efficacy and safety data on the DRI aliskiren. RESULTS: Approximately 70% of essential hypertension is associated with elevated renin levels. Aliskiren is a potent and highly specific inhibitor of renin, with oral bioavailability of 2.6% and an elimination half-life of 40 hours, making it suitable for once-daily oral administration. Aliskiren dose-dependently reduced BP, inhibited plasma renin activity (PRA), attenuated renal damage in animal models, and showed efficient and longer- lasting blockade of the RAAS in normotensive human subjects compared with other RAAS inhibitors. The clinical efficacy and safety of aliskiren have been evaluated both as monotherapy and in combination with other antihypertensive agents in phase II and phase III trials of patients with mild to severe hypertension. When used as monotherapy, aliskiren led to significant dose-dependent reductions in BP from baseline that were greater than those obtained with placebo and comparable with those achieved with an angiotensin II receptor blocker (ARB). The combination of aliskiren with a diuretic, a calcium channel blocker (CCB), an angiotensin-converting enzyme inhibitor (ACEI), or an ARB generally had greater and longer-lasting BP-lowering efficacy than did single agents alone. Aliskiren also countered the reactive increase in PRA caused by diuretic, CC B, ACEI, and ARB therapy. Once-daily treatment with aliskiren was well tolerated. CONCLUSIONS: As a DRI, aliskiren blocks the RAAS more completely than do other current downstream RAAS inhibitors. When used once daily, aliskiren is a safe and effective antihypertensive agent that can be used as monotherapy or in combination with other agents to provide additional options to improve BP control.

Clinical pharmacology of antihypertensive therapy.

Adequate control of blood pressure poses challenges for hypertensive patients and their physicians. Success rates of greater than 80% in reducing blood pressure to target values among high-risk hypertensive patients reported by several recent clinical trials argue that effective medications currently are available. Yet, only 34% of hypertensive patients in the United States are at their goal blood pressure according to the most recent national survey. Rational selection of antihypertensive drugs that target both the patient's blood pressure and comorbid conditions coupled with more frequent use of low-dose drug combinations that have additive efficacy and low adverse-effect profiles could improve significantly US blood pressure control rates and have a positive impact on hypertension-related cardiovascular and renal mortality and morbidity. This article reviews the pharmacokinetic and pharmacodynamic principles that underlie the actions of drugs in each of the classes of antihypertensive agents when used alone and in combination, provides practical pharmacologic information about the drugs most frequently prescribed for treatment of hypertension in the outpatient setting, and summarizes the current data influencing the selection of drugs that might be used most effectively in combination for the majority of hypertensive patients whose blood pressures are not controlled adequately by single-drug therapy.

Is it time to move to multidrug combinations?

The clinical benefit of aggressive blood pressure (BP) control in reducing adverse cardiovascular and renal outcomes is well documented. However, a majority of patients with hypertension remain poorly controlled with monotherapy and require two or more agents to achieve their target BP levels. Patients with hypertension who also have diabetes or renal disease benefit from even lower BP targets, but may be more difficult to treat and require three or more drugs to achieve control. Using two or more drugs, each at lower doses, is usually more effective and less commonly associated with adverse effects than higher doses of a single drug. With the increasing prevalence of diabetes and renal disease, the treatment of hypertensive patients with multidrug combinations will become even more common. Knowing how specific combinations can be used effectively will be an important component of the treatment strategy for hypertension.