The ongoing telmisartan alone and in combination with ramipril global endpoint trial program

Studies in Zebrafish Demonstrate That CNNM2 and NT5C2 Are Most Likely the Causal Genes at the Blood Pressure-Associated Locus on Human Chromosome 10q24.32

Background: Globally, high blood pressure (BP) is the most important risk factor for cardiovascular disease. Several genome-wide association studies (GWAS) have identified variants associated with BP traits at more than 535 chromosomal loci with genome-wide significance. The post-GWAS challenge is to annotate the most likely causal gene(s) at each locus. Chromosome 10q24.32 is a locus associated with BP that encompasses five genes: CYP17A1, BORCS7, AS3MT, CNNM2, and NT5C2 and warrants investigation to determine the specific gene or genes responsible for the phenotype. Aim: To identify the most likely causal gene(s) associated with BP at the 10q24.32 locus using zebrafish as an animal model. Results: We report significantly higher blood flow, increased arterial pulse, and elevated linear velocity in zebrafish larvae with cnnm2 and nt5c2 knocked down using gene-specific splice modification transcriptional morpholinos, compared with controls. No differences in blood-flow parameters were observed after as3mt, borcs7, or cyp17a1 knockdown. There was no effect on vessel diameter in animals with any of the four genes knocked down. At the molecular level, expression of hypertension markers (crp and ace) was significantly increased in cnnm2 and nt5c2 knockdown larvae. Further, the results obtained by morpholino knockdown were validated using zebrafish knockout (KO) lines with cnnm2 and nt5c2 deficiency, again resulting in higher blood flow, increased arterial pulse, and elevated linear velocity. Analysis of nt5c2a KO larvae demonstrated that lack of this gene resulted in reduced expression of cnnm2a, with reciprocal downregulation of nt5c2a in cnnm2a KO larvae. Staining of whole-blood smears from nt5c2 mutants revealed that KO of this gene might be associated with an acute lymphoblastic leukemia phenotype, consistent with literature reports. Additional experiments were designed based on previous literature on cnnm2a mutant zebrafish revealed impaired renal function, high levels of renin, and significantly increased expression of the ren gene, leading us to hypothesize that the observed elevated blood-flow parameters may be attributable to triggering of the renin-angiotensin-aldosterone signaling pathway. Conclusion: Our zebrafish data establish CNNM2 and NT5C2 as the most likely causal genes at the 10q24.32 BP locus and indicate that they trigger separate downstream mechanistic pathways.

Effects of telmisartan and linagliptin when used in combination on blood pressure and oxidative stress in rats with 2-kidney-1-clip hypertension

OBJECTIVE

To investigate the effects of linagliptin alone and in combination with the angiotensin II receptor blocker (ARB), telmisartan on blood pressure (BP), kidney function, heart morphology and oxidative stress in rats with renovascular hypertension.

METHODS

Fifty-seven male Wistar rats underwent unilateral surgical stenosis of the renal artery [2-kidney-1-clip (2k1c) method]. Animals were randomly divided into four treatment groups (n = 14-18 per group) receiving: telmisartan (10 mg/kg per day in drinking water), linagliptin (89 ppm in chow), combination (linagliptin 89 ppm + telmisartan 10 mg/kg per day) or placebo. An additional group of 12 rats underwent sham surgery. BP was measured one week after surgery. Hypertensive animals entered a 16-week dosing period. BP was measured 2, 4, 8, 12 and 16 weeks after the initiation of treatment. Blood and urine were tested for assessment of kidney function and oxidative stress 6, 10, 14 and 18 weeks after surgery. Blood and urine sampling and organ harvesting were finally performed.

RESULTS

Renal stenosis caused an increase in mean ± SD systolic BP as compared with the sham group (157.7 ± 29.3 vs. 106.2 ± 20.5 mmHg, respectively; P < 0.001). Telmisartan alone and in combination with linagliptin, normalized SBP (111.1 ± 24.3 mmHg and 100.4 ± 13.9 mmHg, respectively; P < 0.001 vs. placebo). Telmisartan alone and in combination with linagliptin significantly prevented cardiac hypertrophy, measured by heart weight and myocyte diameter. Renal function measured by cystatin C was not affected by 2k1c surgery. Telmisartan significantly increased plasma concentration of cystatin C. 2k1c surgery initiated fibrosis in both kidneys. Telmisartan promoted further fibrotic changes in the clipped kidney, as measured by protein expression of Col1a1 and histology for interstitial fibrosis and glomerulosclerosis. In non-clipped kidneys, telmisartan demonstrated antifibrotic properties, reducing Col1a1 protein expression. Plasma levels of oxidized low-density lipoprotein were higher in the placebo-treated 2k1c rats as compared to sham-operated animals. The increase was abolished by linagliptin alone (P = 0.03 vs. placebo) and in combination with telmisartan (P = 0.02 vs. placebo). Combination therapy also significantly reduced plasma concentration of carbonyl proteins (P = 0.04 vs. placebo).

CONCLUSION

Inhibition of type 4 dipeptidyl peptidase with linagliptin did not counter BP-lowering effects of ARB in 2k1c rats. Linagliptin reduced lipid and protein oxidation in 2k1c rats, and this effect was BP-independent.

Impact of telmisartan on cardiovascular outcome in hypertensive patients at high risk: a Telmisartan Randomised AssessmeNt Study in ACE iNtolerant subjects with cardiovascular Disease subanalysis

BACKGROUND

In the Telmisartan Randomised AssessmeNt Study in ACE iNtolerant subjects with cardiovascular Disease, all patients were at high cardiovascular risk, and a substantial proportion were hypertensive. We performed a post-hoc analysis to explore the hypothesis that telmisartan has a differential action in hypertensive vs. nonhypertensive patients.

METHODS

The primary four-fold endpoint (composite of cardiovascular death, myocardial infarction (MI), stroke, or hospitalization for heart failure), the secondary three-fold endpoint (cardiovascular death, MI, and stroke), the individual components, new onset of left ventricular hypertrophy (LVH), and new onset of albuminuria were analyzed.

RESULTS

There was no evidence for a significantly differential treatment effect of telmisartan in hypertensive and nonhypertensive patients for any endpoints, although the occurrence of the secondary three-fold endpoint was significantly lower in the telmisartan group (13.0%) compared with placebo (15.0%, P < 0.05) only in hypertensive patients. Moreover, data from this post-hoc analysis suggest that MI may be less frequent in hypertensive patients treated with telmisartan (3.8 vs. 5.1%; P < 0.05). Telmisartan may also reduce new onset of LVH (nonhypertensive patients P < 0.05; hypertensive patients P < 0.001) in both subgroups, and new onset of microalbuminuria and macroalbuminuria in hypertensive patients (P < 0.001 and P < 0.01, respectively).The effect of telmisartan in hypertensive and nonhypertensive patients at high cardiovascular risk was not different. This post-hoc analysis suggests that MI may be further reduced by telmisartan in hypertensive patients. Further investigations are needed to study the hypotheses raised by this explanatory analysis.

Angiotensin-converting enzyme inhibitors versus angiotensin receptor blockers for end-stage renal disease/mortality in type 2 diabetes

AIMS

To compare angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) for end-stage renal disease (ESRD) development and all-cause mortality in veterans with macroalbuminuria and with newly documented type 2 diabetes.

METHODS

A retrospective cohort study utilizing data from the national Department of Veterans Affairs (VA) databases. The study followed 5166 subjects without a history of use of ACEIs or ARBs. To control for differences in baseline characteristics between groups, comparisons of subjects ACEIs and ARBs were made by incorporating propensity scores analysis into multivariate logistic regression. This resulted in adjusted odds ratios and 95% confidence intervals for ESRD development and all-cause mortality.

RESULTS

The sample was followed up to five years with a mean follow-up of three years. Subjects taking ACEIs has lower odds of ESRD development (OR, 0.33 [95% CI, 0.13-0.82]) and all-cause mortality (OR, 0.10 [95% CI, 0.04-0.21]) than ARBs.

CONCLUSIONS

This study shows that ACEIs are associated with lower ESRD development and all-cause mortality than ARBs. This may have implications for guidelines which currently suggest that these two therapeutic classes provide similar benefits in people with newly diagnosed type 2 diabetes and macroalbuminuria.

Hypertension management in the high cardiovascular risk population

The incidence of hypertension is increasing every year. Blood pressure (BP) control is an important therapeutic goal for the slowing of progression as well as for the prevention of Cardiovascular disease. The management of hypertension in the high cardiovascular risk population remains a real challenge as the population continues to age, the incidence of diabetes increases, and more and more people survive acute myocardial infarction. We will review hypertension management in the high cardiovascular risk population: patients with coronary heart disease (CHD) and heart failure (HF) as well as in diabetic patients.

Effects of suboptimal doses of the AT1 receptor blocker, telmisartan, with the angiotensin-converting enzyme inhibitor, ramipril, on cerebral arterioles in spontaneously hypertensive rat

OBJECTIVE

Antihypertensive treatment with standard clinical doses of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) reverses cerebral arteriolar remodeling, thus restoring dilatation and the lower limit of cerebral blood flow (CBF) autoregulation (LL CBF AR). In humans, a combination of standard clinical doses of the two drugs does not produce greater protection against stroke than that obtained with single-drug treatments and increases the risk of side-effects. We hypothesized that a combination of suboptimal doses of the ARB, telmisartan (TEL) and of the ACEI, ramipril (RAM), could be a well tolerated and effective treatment of hypertension-induced remodeling of cerebral arterioles.

DESIGN

We studied the impact of 3-month oral treatment with TEL (0.5 or 0.8 mg/kg per day) or RAM (0.1 or 0.25mg/ kg per day) alone or in combination (TEL0.8 + RAM0.1 or TEL0.5 + RAM0.25) on the cerebral circulation of the spontaneously hypertensive rats (SHRs). Normotensive Wistar-Kyoto rats (WKYs) were taken as controls.

METHODS

Cerebral arteriolar pressure, CBF and internal diameter were measured via an open-skull preparation at baseline and during hypotension before and after deactivation (EDTA).

RESULTS

Combinations normalized cerebral arteriolar pressure, whereas drugs alone had no significant impact. TEL0.8 + RAM0.1 showed the greatest effect on arteriolar internal diameter (SHRs 42+/-16, WKYs 59+/-16microm, TEL0.5 + RAM0.25 50+/-6, TEL0.8 + RAM0.1 62+/-18, P<0.05) and normalized LL CBF AR (SHRs 77+/-28, WKYs 53+/-17 mmHg, TEL0.8 + RAM0.1 50+/-10, P<0.05).

CONCLUSION

The combination of suboptimal doses of TEL and RAM with an 8 : 1 ratio has the greatest effect on cerebral circulation and could represent well tolerated and efficient treatment of cerebral ischemia and stroke.

Telmisartan in high-risk cardiovascular patients

Increasing attention is being devoted to the use of combination therapy with angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) in order to achieve maximal blockade of the renin-angiotensin system (RAS) in patients at high risk of cardiovascular events. This approach has been adopted in the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET), which compared the effects of the ARB telmisartan and the ACE inhibitor ramipril, alone and in combination, on cardiovascular mortality and morbidity in high-risk patients with vascular disease or diabetes mellitus and end-organ damage. The results showed that telmisartan was as effective as ramipril for the primary cardiovascular outcome during a 56-month follow-up but was better tolerated. However, dual RAS blockade was not associated with any additional benefits, and the incidence of adverse events was greater with the combination. Based on these findings, optimal cardioprotective strategies in high-risk patients are likely to involve the addition of either telmisartan or ramipril on top of the patient's usual care, but not both. The choice of agent to be used in the long term could be based on other considerations, such as compliance and safety. Both cough and angioedema were higher with ramipril than telmisartan during the 56-month follow-up period in ONTARGET.

Use of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker therapy to reduce cardiovascular events in high-risk patients: part 2

As presented previously in Part 1 of this 2-part article, many long-term clinical trials provide overwhelming evidence of the benefits of angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) across the cardiovascular continuum. Trials also indicate additive or synergistic effects of combination therapy in renal disease and heart failure. Part 2, which is presented here, discusses the extensive interaction of the renin-angiotensin system (RAS) with the cellular and molecular pathophysiology of cardiovascular disease and the cross-continuum effects of ARBs and ACE inhibitors, which raises the possibility that RAS inhibition can offer protection in high-risk patients who do not have symptoms. Although trial evidence supports the effectiveness of monotherapy, the benefits of combined ACE inhibitor/ARB therapy in high-risk patients await confirmation. Ongoing clinical research will provide new and important information regarding the efficacy of specific combination (ACE inhibitor/ARB) therapies.

Rationale for double renin-angiotensin-aldosterone system blockade

The clinical benefits of both angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) extend beyond blood pressure reduction to encompass tissue-protective effects in target organs, such as the heart, vasculature, and kidneys, that underlie the reductions in cardiovascular mortality and morbidity seen in large outcome trials. However, these effects are achieved by different mechanisms. ACE inhibitors reduce circulating and tissue angiotensin II levels and potentiate the beneficial effects of bradykinin, including generation of nitric oxide (NO). By contrast, the protective effects of ARBs are owing to the blockade of the angiotensin II type 1 (AT(1)) receptors and possibly also to the stimulation of angiotensin II type 2 (AT(2)) receptors, again resulting in NO release. In addition, some ARBs, such as telmisartan, are selective activators of peroxisome proliferator-activated receptor-gamma (PPAR-gamma), thereby increasing insulin sensitivity. In contrast to other PPAR-gamma ligands, such as the thiazolidinediones, activation of this receptor by telmisartan does not result in weight gain. The complementary mechanisms of action of ACE inhibitors and ARBs create a rationale for combination therapy in high-risk patients. The benefits of this approach with telmisartan are being investigated in clinical trials, such as the Ongoing Telmisartan Alone in Combination with Ramipril Global Endpoint Trial (ONTARGET).

Reducing diabetes incidence through the inhibition of the renin–angiotensin system: a strategy for reducing cardiovascular mortality and morbidity?

The prevalence of type 2 diabetes is increasing worldwide, and prevention of the disease is a key objective. Several clinical trials reported a consistent reduction in the incidence of newly diagnosed diabetes in high-risk patients treated with renin-angiotensin system-inhibiting drugs. In all those trials, however, diabetes reduction was either a post-hoc analysis result or a secondary endpoint. Therefore, we need the results of ongoing specific prospectively designed trials, with new-onset diabetes as the principal endpoint.

Angiotensin II Receptor Blockers: The Importance of Dose in Cardiovascular and Renal Risk Reduction

Numerous clinical studies have established that angiotensin II receptor blockers are effective as antihypertensive therapy and are well tolerated. Studies demonstrate that adding an angiotensin II receptor blocker to existing antihypertensive regimens reduces cardiovascular and renal risk, which may, in part, be a result of blocking the effects of angiotensin II. Though the antihypertensive dose response of these agents is well documented, the dose response for optimal target organ protection has not yet been clarified. A review of recent studies of angiotensin II receptor blockers in hypertension, acute myocardial infarction, heart failure, and nephropathy provide some data on specific drugs, doses, and risk reduction. Taken as a whole, these studies suggest the highest doses tested, which are at the upper limit of the antihypertensive range, provide greater risk reduction than lower doses. What is unknown is whether even higher doses or full-dose angiotensin II receptor blockers plus full-dose angiotensin-converting enzyme inhibitors might provide even greater risk reduction. Data from ongoing trials will provide additional insight.

Combination ACE Inhibitor and Angiotensin Receptor Blocker Therapy-Future Considerations

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are regularly prescribed for the management of hypertension. Each of these drug classes has also been shown to provide survival benefits for patients with heart failure, proteinuric chronic kidney disease, and/or a high cardiac risk profile. The individual gains seen with each of these drug classes have led to speculation that their combination might offer additive if not synergistic outcome benefits. The foundation of this hypothesis, although biologically possible, has thus far not been sufficiently well proven to support the everyday use of these 2 drug classes in combination. Additional outcomes trials, which are currently proceeding to their conclusion, may provide the necessary proof to support an expanded use of these 2 drug classes in combination.

Effective treatment of hypertension by AT(1) receptor antagonism: the past and future of telmisartan

Lowering blood pressure is the most effective treatment method to ensure a reduction in the total risk for cardiovascular morbidity and mortality. The renin-angiotensin system plays an important role in volume homeostasis and blood pressure regulation and is a target for several groups of pharmaceutical agents. Angiotensin II receptor blockers represent the newest class of antihypertensive compounds. They prevent the binding of angiotensin II to the subtype 1 receptor (AT(1)), which is believed to mediate most of the physiological actions relevant to the regulation of blood pressure. Telmisartan, a widely used AT(1) receptor antagonist, is a highly selective compound with high potency, a long duration of action and a tolerability profile similar to placebo. Numerous randomized clinical trials and community-based studies have demonstrated that oral telmisartan and combinations of telmisartan with hydrochlorothiazide are at least as effective in lowering blood pressure as all other hypertensive medications. This has been demonstrated in different populations of adult patients with mild-to-moderate essential hypertension, including patients with coexisting Type 2 diabetes, metabolic syndrome or renal impairment. Several large-scale, long-term, clinical endpoint studies are in progress to assess the beneficial effects of telmisartan on hypertension-related end-organ damage in patients at high risk of renal, cardiac and vascular damage whose blood pressure is well controlled. The most recent data from clinical trials and latest research regarding telmisartan will be reviewed in this article.

Optimizing hypertension management in clinical practice

A clear relationship exists between elevated blood pressure (BP) and various manifestations of cardiovascular disease. Despite the availability of numerous treatment guidelines, hypertension remains inadequately controlled, with only a small proportion of patients achieving target BP levels. Many factors, both patient and physician related, contribute to this poor level of hypertension control. Major determinants include the implementation of inappropriate treatment regimens that do not enable patients to achieve goal and poor patient compliance. For example, it is widely acknowledged that most patients require two or more antihypertensive drugs to achieve BP goal; however, physicians may be reluctant to employ such treatment strategies. The aim of this review is to explore factors that contribute to poor hypertension control rates and how to overcome these, including the rationale for selecting combination therapy, with particular reference to angiotensin II receptor blocker combinations.

Meta-analysis: inhibition of renin-angiotensin system prevents new-onset atrial fibrillation

BACKGROUND

Epidemiologic studies suggest that inhibition of renin-angiotensin system with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may prevent development of atrial fibrillation (AF).

OBJECTIVE

The objective of the study was to assess if there is significant indication for using angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in the prevention of new-onset AF and to identify the target patient population.

METHODS

PubMed and Cochrane clinical trials database were searched from 1980 through March 2005 together with the review of citations. Nine randomized controlled human trials reporting the prevention of new-onset AF by inhibition of renin-angiotensin system were identified. Information about study design, follow-up, intervention, population, outcomes, and methodology quality was extracted.

RESULTS

The mean follow-up of the studies ranged from 6 months to 6.1 year. The pooled estimate using random effects model was 0.82 (95% CI 0.70-0.97) for prevention of new-onset AF and 0.61 (95% CI 0.46-0.83) for primary prevention of AF. The angiotensin-converting enzyme inhibitors (0.75, 95% CI 0.57-0.99) had greater protective effect than angiotensin receptor blockers (0.81, 95% CI 0.62-1.06). Patients with heart failure benefited the most (0.57, 95% CI 0.37-0.89). The test for heterogeneity between studies was significant. There was no consistent visual or statistical evidence of publication bias.

CONCLUSION

The use of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers had an overall effect of 18% risk reduction in new-onset AF across the trials and 43% risk reduction in patients with heart failure.

Diabetes mellitus-associated atherosclerosis: mechanisms involved and potential for pharmacological invention

While diabetes mellitus is most often associated with hypertension, dyslipidemia, and obesity, these factors do not fully account for the increased burden of cardiovascular disease in patients with the disease. This strengthens the need for comprehensive studies investigating the underlying mechanisms mediating diabetic cardiovascular disease and, more specifically, diabetes-associated atherosclerosis. In addition to the recognized metabolic abnormalities associated with diabetes mellitus, upregulation of putative pathological pathways such as advanced glycation end products, the renin-angiotensin system, oxidative stress, and increased expression of growth factors and cytokines have been shown to play a causal role in atherosclerotic plaque formation and may explain the increased risk of macrovascular complications. This review discusses the methods used to assess the development of atherosclerosis in the clinic as well as addressing novel biomarkers of atherosclerosis, such as low-density lipoprotein receptor-1. Experimental models of diabetes-associated atherosclerosis are discussed, such as the streptozocin-induced diabetic apolipoprotein E knockout mouse. Results of major clinical trials with inhibitors of putative atherosclerotic pathways are presented. Other topics covered include the role of HMG-CoA reductase inhibitors and fibric acid derivatives with respect to their lipid-altering ability, as well as their emerging pleiotropic anti-atherogenic actions; the effect of inhibiting the renin-angiotensin system by either ACE inhibition or angiotensin II receptor antagonism; the effect of glycemic control and, in particular, the promising role of thiazolidinediones with respect to their direct anti-atherogenic actions; and newly emerging mediators of diabetes-associated atherosclerosis, such as advanced glycation end products, vascular endothelial growth factor and platelet-derived growth factor. Overall, this review aims to highlight the observation that various pathways, both independently and in concert, appear to contribute toward the pathology of diabetes-associated atherosclerosis. Furthermore, it reflects the need for combination therapy to combat this disease.

Blood Pressure as a Risk Factor for Stroke and the Impact of Antihypertensive Treatment

We review hypertension and blood pressure levels as risk factors for stroke and the impact of antihypertensive treatment on the prevention of first stroke event and of recurrent stroke, not only with respect to the prevention of vascular events but also the prevention of cognitive deterioration, dementia, and physical disability. We review whether pharmacological blockage of the renin-angiotensin system has additional long-term effects over that of control of blood pressure levels alone, and the benefit of treatment with antihypertensive drugs in normotensive patients. Therapeutic objectives for blood pressure levels after stroke are defined together with recommendations of drugs and doses which have been demonstrated to have the greatest benefit in the prevention of stroke.

Antidiabetic mechanisms of angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists: beyond the renin-angiotensin system

Several lines of evidence suggest that angiotensin-converting enzyme (ACE) inhibitors and some angiotensin II receptor blockers (ARBs) may improve insulin sensitivity and decrease the risk for type 2 diabetes. It is widely assumed that the potential antidiabetic properties of these agents are largely mediated by their ability to interfere with the adverse metabolic effects of angiotensin II. However, recent studies suggest that ACE inhibitors might improve glucose metabolism primarily through effects on kinin-nitric oxide pathways. In addition, one ARB in particular, telmisartan, has been found to effectively activate the peroxisome proliferator activated receptor gamma (PPARgamma), a well-known target for insulin-sensitizing, antidiabetic drugs. Thus, the beneficial metabolic effects of some ACE inhibitors and ARBs may go well beyond their effects on the renin-angiotensin system. Moreover, the identification of telmisartan as a unique angiotensin II receptor antagonist with selective PPARgamma modulating ability suggests new opportunities for developing third-generation ARBs and PPARgamma activators, with enhanced potential for treating hypertension, diabetes and the metabolic syndrome.

Why blockade of the renin–angiotensin system reduces the incidence of new-onset diabetes

Recent trials have suggested that inhibitors of the renin-angiotensin system (RAS), such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs), may reduce the incidence of new-onset diabetes in patients with or without hypertension and at high risk of developing diabetes. In this review, we critically evaluate the evidence from recent clinical trials for such a potential preventive effect of ACE inhibitors and ARBs, including a meta-analysis of these recent trials. The reduced incidence of diabetes in patients at high risk of developing diabetes by ACE inhibitors or ARBs has been explained by haemodynamic effects, such as improved delivery of insulin and glucose to the peripheral skeletal muscle, and non-haemodynamic effects, including direct effects on glucose transport and insulin signalling pathways, all of which decrease insulin resistance. There is now evidence that the pancreas may contain an in situ active RAS, which appears to be upregulated in an animal model of type 2 diabetes. Thus, ACE inhibitors and ARBs may act by attenuating the deleterious effect of angiotensin II on vasoconstriction, fibrosis, inflammation, apoptosis and beta-cell death in the pancreas, thereby protecting a critical beta-cell mass essential for insulin production. New evidence is presented that ACE inhibitors and ARBs may delay or prevent the development of insulin resistance and diabetes, for which novel mechanisms are suggested. The actions of agents that interrupt the RAS on insulin resistance, obesity and diabetes warrant further investigation in other animal models. Prospective clinical studies with the primary endpoint of the prevention of diabetes are now indicated to (i) further explore whether the inhibitors of the RAS are superior compared to other antihypertensive agents such as calcium channel blockers (CCBs) and (ii) to evaluate the potential beneficial effects of combination antihypertensive regimens on the development of diabetes.

Sexual Dysfunction in Male Patients with Hypertension

Evidence suggests that arterial hypertension, in addition to being a cardiovascular and renal risk factor, may also be associated with an impairment of male sexual function. Since other cardiovascular risk factors, especially diabetes mellitus, have also been shown to correlate with impaired sexual function it has been proposed that sexual and especially erectile dysfunction may, at least in part, represent just another manifestation of atherosclerotic vascular disease. In addition to hypertension itself, sexual function in male hypertensive patients may also be affected by antihypertensive drug treatment. Available evidence suggests that centrally acting sympatholytic agents, beta-adrenoceptor antagonists (beta-blockers) and diuretics may have the potential to further impair sexual function. Calcium channel antagonists and ACE inhibitors may be neutral with respect to this endpoint. Preliminary data from several randomised and open studies have suggested that angiotensin II (AT)(1)-receptor antagonists may even be associated with an improvement of sexual function. However, many aspects of the interaction between hypertension, antihypertensive drug treatment and male sexual function remain unclear. Among other factors, the relative contribution of disease labelling both to the higher incidence of sexual dysfunction in hypertensive versus normotensive males and to the negative impact of treatment remains an open question. Furthermore, dose dependence of the observed effects of antihypertensive agents on sexual function, the role of combination therapy and the anticipation of proposed adverse effects of treatment are unresolved issues. Thus, more data from studies of high quality using standardised definitions and procedures are urgently needed to at least partially resolve some of the many open questions.

Comparison of valsartan 160 mg with lisinopril 20 mg, given as monotherapy or in combination with a diuretic, for the treatment of hypertension: the Blood Pressure Reduction and Tolerability of Valsartan in Comparison with Lisinopril (PREVAIL) study

BACKGROUND

The goal of antihypertensive therapy is to provide good blood pressure (BP) control without eliciting adverse effects.

OBJECTIVE

This study compared the risk-benefit profile of the angiotensin II receptor blocker valsartan with that of the angiotensin-converting enzyme inhibitor lisinopril in patients with mild to severe hypertension. The primary objective was to show that the equipotent BP-lowering effect of the valsartan-based treatment is accompanied by a better tolerability profile.

METHODS

This 16-week, randomized, double-blind, parallel-group study was conducted at 88 outpatient centers across Italy. After a 2-week placebo run-in period, patients aged > or = 18 years with mild to severe hypertension (systolic BP [SBP], 160-220 mm Hg; diastolic BP [DBP], 95-110 mm Hg) were eligible. Patients were randomized to receive once-daily, oral, self-administered treatment with valsartan 160-mg capsules or lisinopril 20-mg capsules under double-blind conditions for 4 weeks. Responders continued monotherapy, whereas nonresponders had hydrochlorothiazide 12.5 mg added for the final 12 weeks of the study. The 2 primary variables used to assess the equivalence of therapeutic efficacy of the 2 regimens were sitting SBP and sitting DBP, which were measured at weeks 0 (baseline), 4, 8, and 16. The rate of drug-related adverse events (AEs) was used to assess whether 1 treatment had a better tolerability profile than the other. Tolerability was assessed by collecting information about AEs by means of questioning the patient or physical examination at each visit.

RESULTS

A total of 1213 patients were enrolled (635 men, 578 women; mean [SD] age, 54.5 [10.1] years [range, 28-78 years]). The study was completed by 1100 patients (553 receiving valsartan and 547 receiving lisinopril). Fifty-one patients (8.4%) treated with valsartan and 62 (10.2%) [corrected] treated with lisinopril withdrew, mainly because of AEs (9 [1.5%] and 23 patients [3.8%], respectively). The valsartan- and lisinopril-based treatments were similarly effective in reducing sitting BP, with mean SBP/DBP reductions of 31.2/15.9 mm Hg and 31.4/15.9 mm Hg, respectively. At the end of the study, BP was controlled in 82.6% [corrected] of the patients receiving valsartan and 81.6% of those receiving lisinopril. AEs were experienced by 5.1% of the patients treated with valsartan and 10.7% of those treated with lisinopril (P=.0001), with dry cough observed in 1.0% and 7.2% of patients, respectively (P<0.001).

CONCLUSIONS

Valsartan and lisinopril were both highly effective in controlling BP in these patients with mild to severe hypertension, but valsartan was associated with a significantly reduced risk for AEs, especially cough.

[Pharmacological and clinical profile of telmisartan, a selective angiotensin II type-1 receptor blocker]

Telmisartan (Micardis) is a potent, long-lasting, nonpeptide angiotensin II type-1 (AT(1)) receptor blocker (ARB) that is indicated for the treatment of essential hypertension. In receptor binding studies, telmisartan showed a high affinity and selectivity for the human AT(1) receptors compared with AT(2) receptors and a slower dissociation rate from the human AT(1) receptor than those of ARBs. In isolated aorta rings, telmisartan was shown to be an insurmountable antagonist of AII-induced contractions. The inhibitory effects of telmisartan on AII-induced contraction persisted even after wash-out procedures. In animal models such as spontaneous hypertension rats and renovascular hypertensive rats, telmisartan produced the consistent reduction of blood pressure. Furthermore, there were no rebound phenomenon and no tolerance to the drug developed in the repeated oral administration. Telmisartan has a longer terminal elimination half-life (about 24 h) than the other ARBs. In patients with mild-moderate hypertension, trough/peak ratios for telmisartan were above 80%. In Japanese patients with mild-moderate hypertension, telmisartan produced a significant reduction in blood pressure (effective rate: 76.0%) with a good safety profile. Therefore, telmisartan is expected to be effective in the treatment of hypertension, producing sustained 24-h blood pressure control.

Dual Blockade of the Renin—Angiotensin System in Diabetic Nephropathy

OBJECTIVE:

To review the literature concerning dual blockade of the renin—angiotensin system (RAS) with an angiotensin-converting enzyme (ACE) inhibitor and an angiotensin II receptor blocker (ARB) in diabetic nephrophathy.

DATA SOURCES:

MEDLINE (1998—September 2003), EMBASE (1998–September 2003), and International Pharmaceutical Abstracts (1998–September 2003) were used to access the literature. Search terms included angiotensin-converting enzyme inhibitor, angiotensin II receptor blocker, diabetic nephropathy, dual blockade, renin—angiotensin system, and combination therapy.

DATA SYNTHESIS:

Monotherapy with an ACE inhibitor provides incomplete blockade of the RAS. Dual blockade of the RAS has been studied in approximately 300 patients with diabetic nephropathy. Recent randomized controlled studies suggest that dual blockade using an ACE inhibitor and an ARB in diabetic nephropathy is well tolerated and will provide an additional 11–43% reduction in albuminuria versus monotherapy.

CONCLUSIONS:

Dual blockade of the RAS using an ACE inhibitor and an ARB provide statistically significant reductions in albuminuria and blood pressure. Use of dual blockade is safe, but requires additional monitoring for hyperkalemia. Long-term studies are needed to determine whether the decrease in albuminuria will correlate with an actual improvement from overt proteinuria to microalbuminuria or a decreased incidence of end-stage renal disease in the overall diabetic population.

The tissue renin-angiotensin-aldosterone system in diabetes mellitus

Diabetes is associated with an inordinate burden of cardiovascular and renal disease, which is expected to accelerate during the next few decades. The relationship between the renin-angiotensin system (RAS) and diabetic macrovascular and microvascular disease is well established. The contribution of the tissue RAS in disease pathogenesis has recently been the focus of much interest, and has prompted investigators to explore the use of high-dose RAS inhibition with monotherapy or combination therapy to provide a more complete blockade of the actions of angiotensin II, beyond lowering blood pressure. There is now evidence to support this approach to maximize cardiovascular and renal protection. Optimal dosing strategies remain uncertain, but tissue specificity does not appear to be important if the doses of angiotensin-converting enzyme-I and angiotensin-receptor binders are high enough. The purpose of this review is to highlight our current understanding of the role of the tissue RAS in the pathogenesis of diabetic end-organ damage and ongoing strategies to interfere pharmacologically.

How cost-effective are new preventive strategies for cardiovascular disease?

Costs of providing a particular medical service can be measured, but it is more difficult to assess whether the service provides good value for the money spent. Rigorous trials have demonstrated the health benefits connected with interventions for treatment and prevention of cardiovascular disease (CVD), and in-depth analyses of the costs associated with many of those interventions have been performed. Careful use of terminology clearly differentiating among cost-minimization (relative costs of proved equivalent therapeutics), cost-effectiveness (lives saved or years of life added), and cost-benefit (total net effect in monetary terms) analyses is warranted. Although trials commonly assess clinical effectiveness as reductions in mortality or CVD-specific outcomes, improvement in quality of life may be equally important and is expressed in quality-adjusted life-years. Comparisons between therapies can be assessed as a cost-effectiveness ratio. Extensive cost-effectiveness studies have been conducted on many important cardiovascular therapies: (1) beta-blockers and diuretics for multiple CVD outcomes, mortality, and prevention of recurrent myocardial infarction (MI); (2) statins for both primary and secondary prevention of CVD; (3) enalapril for prevention and treatment of congestive heart failure; (4) tissue plasminogen activator treatment of acute MI; (5) coronary artery bypass graft for left main, single-, and 2-vessel coronary artery disease, or severe angina; (6) physician counseling for smoking; and (7) radiofrequency ablation therapy for Wolff-Parkinson-White syndrome. Therapies considered economically attractive include (1) secondary prevention with statins in hyperlipidemia, (2) smoking cessation programs, (3) primary prevention in treatment of high blood pressure with diuretics and beta-blockers, (4) primary prevention with regular exercise programs, (5) secondary prevention with cardiac rehabilitation, and (6) postinfarction treatment with beta-blockers and angiotensin-converting enzyme (ACE) inhibitors. A recent cost-minimization analysis has been performed showing aspirin to be a "best buy" therapy for secondary prevention of CVD. The Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET) and Telmisartan Randomized Assessment Study in ACE-I Intolerant Patients with Cardiovascular Disease (TRANSCEND) program provide potential opportunities for both cost-minimization and cost-effectiveness analyses.