Hemodynamic and neurohormonal effects of the angiotensin II antagonist losartan in patients with congestive heart failure

Addition of an angiotensin receptor blocker to full-dose ACE-inhibition: controversial or common sense?

Both angiotensin-converting enzyme (ACE)-inhibitors and angiotensin receptor blockers (ARBs) interfere with the activity of the renin-angiotensin system (RAS) in a different way. Theoretically, one might expect beneficial effects when they are used in combination, as a more complete suppression of the RAS can be achieved. But can this additional effect still be seen in patients on full-dose ACE-inhibition? Several controlled trials demonstrated that combination therapy can have additional benefits in hypertensive patients, in chronic heart failure patients, and in both diabetic and non-diabetic nephropathy patients. However, the clinical benefit was not always as pronounced as expected and not every patient will benefit from dual blockade of the RAS. There is some evidence of a less pronounced effect of combination therapy when a full dose of the ACE-inhibitor is given. However, it is well known that ACE-inhibitors cannot completely suppress the formation of angiotensin II, in particular, when the RAS is activated. Indeed, clinical trials indicated that add-on therapy with an ARB was especially of use when the RAS remained activated despite full-dose ACE-inhibitor treatment. In summary, combination of a full-dose ACE-inhibitor and an ARB can be a rational choice in selected patients.

[Molecular biology of the heart atrium. New insights into the pathophysiology of atrial fibrillation as well as its clinical implications]

Atrial fibrillation (AF) is the most common clinical arrhythmia and one of the most important factors for embolic stroke. In recent years, a tremendous amount has been learned about the pathophysiology and molecular biology of AF. Thus, pharmacologic interference with specific signal transduction pathways appears promising as a novel antiarrhythmic approach to maintain sinus rhythm and to prevent atrial clot formation. This review highlights the underlying molecular biology of atrial fibrillation, which may also be relevant for AF therapy.

The use of angiotensin receptor blockers in the treatment of chronic heart failure

Angiotensin receptor blockers (ARBs) have a pharmacological role in the treatment of heart failure through their blockade of the effects of angiotensin II. ARBs, however, lack the potential benefits of inhibiting the breakdown of bradykinin that is seen with ACE-Is. Historically, the medical literature assessing ARBs in the treatment of chronic heart failure have been short in duration and primarily focused on surrogate markers of disease severity. Recent, well-designed clinical trials have shed new light on the potential roles of ARBs in the treatment of chronic heart failure and their effects on mortality in this patient population. In comparison to captopril, losartan has been shown to have similar benefits in cardiovascular mortality and morbidity. In patients with systolic dysfunction who are intolerant to ACE-Is, candesartan has been shown to reduce cardiovascular mortality and hospital admissions for heart failure. In combination with ACE-Is, candesartan and valsartan have been shown to improve heart failure morbidity and, with candesartan, reduced cardiovascular mortality in those with systolic dysfunction. These 2 trials show conflicting mortality information regarding the use of triple therapy with ACE-Is, ARBs, and beta-blockers for systolic dysfunction. In patients with heart failure but preserved systolic dysfunction, candesartan showed no effects on mortality and only modest effects on morbidity.

Losartan: a selective angiotensin II type 1 (AT1) receptor antagonist for the treatment of heart failure

Losartan (COZAAR) is the prototype of a new class of potent and selective angiotensin II (AII) type 1 (AT(1)) receptor antagonists with the largest published preclinical and clinical data base. Since all of the AII antagonists are selective for the AT(1) receptor, these drugs should exhibit similar cardiovascular effects. However, since the pharmacokinetic/pharmacodynamic profiles of these agents and their degree of affinity for the AT(1) receptor differ, it is likely that differences in clinical profiles between these drugs exist and will require investigation. Losartan (parent compound), has moderate affinity for the AT(1) receptor (competitive inhibition). Losartan is well-absorbed orally as an active drug and is rapidly converted via oxidation in the human liver to a more potent metabolite (designated E3174) with an affinity 20- to 30-times greater for the AT(1) receptor (non-competitive inhibition). E3174 has a half-life of 6 - 9 h; elimination is via renal and hepatic routes. Antihypertensive and, in heart failure patients, haemodynamic activity is observed over a 24 h period with once daily dosing. Over 6 million patients have been treated for hypertension with continued excellent tolerability. Clinical experience in heart failure is growing, and recent data suggest an improved survival with losartan versus captopril, a drug from the angiotensin-converting-enzyme inhibitor class with proven benefit in this population. The current comprehensive losartan clinical end-point programme (4 large scale morbidity/mortality trials) should provide evidence regarding the efficacy of direct blockade of the AT(1) receptor with losartan compared to standard therapy: 1) The Losartan Heart Failure Survival Study - ELITE II, 2) The Losartan Post-Myocardial Infarction Survival Study - OPTIMAAL, 3) The Losartan Hypertension Survival Study - LIFE and 4) The Losartan Renal Protection Study - RENAAL.

Effects of Angiotensin II Type 1 Receptor Antagonist, Losartan, on Ventilatory Response to Exercise and Neurohormonal Profiles in Patients with Chronic Heart Failure

Chronic heart failure (CHF) is associated with abnormal neurohormonal profiles and increased ventilatory response to exercise. This study determined if treatment with angiotensin II type 1 receptor antagonist, losartan, improves ventilatory efficiency and neurohormonal factors in patients with CHF. Symptom-limited cardiopulmonary exercise testing was performed after a 2-week placebo period (baseline) and after 16 weeks of treatment with losartan (40 +/- 4 mg/day) in 10 patients with CHF (age 57.7 +/- 3.7 years). Echocardiogram, daily physical activity (by the specific activity scale), and neurohormones were evaluated. Treatment with losartan increased left ventricular ejection fraction (baseline vs. losartan: 31 +/- 3 vs. 39 +/- 3%, p<0.01) and specific activity scale score (5.3 +/- 0.5 vs. 6.4 +/- 0.4 METS, p<0.05). Losartan decreased the ventilatory response to carbon dioxide production during exercise (VE/VCO2 slope: 34.6 +/- 2.4 vs. 32.0 +/- 2.2, p<0.05). Plasma brain natriuretic peptide concentrations were decreased after therapy (301 +/- 79 vs. 176 +/- 53 pg/ml, p<0.05). In summary, the results of this open-label, uncontrolled study suggest that chronic treatment with losartan may improve ventilatory efficiency and decrease plasma brain natriuretic peptide concentrations with the improvement of physical activity and left ventricular systolic function in patients with CHF.

AT1-receptor blockade and sympathetic neurotransmission in cardiovascular disease

1. The present survey is dealing with the interactions between the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system (SNS) in various organs and tissues, with an emphasis on the angiotensin AT-receptors located at the sympathetic nerve endings. 2. Angiotensin II, the main effector of the RAAS is known to stimulate sympathetic nerve traffic and its sequelae in numerous organs and tissues, such as the central nervous system, the adrenal medulla, the sympathetic ganglia and the sympathetic nerve endings. These stimulatory effects are mediated by AT(1)-receptors and counteracted by AT(1)-receptor antagonists. 3. Sympatho-inhibition at the level of the sympathetic nerve ending appears to be a class effect of the AT(1)-receptor blockers, mediated by presynaptic AT(1)-receptors. With respect to the ratio pre-/postsynaptic AT(1)-receptor antagonism important quantitative differences between the various compounds were found. 4. Both the pre- and postjunctional receptors at the sympathetic nerve endings belong to the AT(1)-receptor population. However, the presynaptic receptors belong to the AT(1B)-subtype, whereas the postjunctional receptors probably belong to a different AT(1)-receptor subpopulation. 5. Sympatho-inhibition is a class effect of the AT(1)-receptor antagonists. In conditions in which the SNS plays a pathophysiological role, such as hypertension and congestive heart failure, this property may well be of therapeutic relevance.

Early and chronic captopril or Losartan therapy reduces infarct size and avoids congestive heart failure after myocardial infarction in rats

BACKGROUND

Angiotensin converting enzyme (ACE) inhibitors and angiotensin II AT1-receptor antagonists prolong survival in experimental postischemic heart failure (CHF) in rats. The aim of this study was to investigate whether potential beneficial effects of early and long-term therapy with low doses of captopril or losartan occur in hemodynamics and heart morphometry, as well as in infarct size during establishment of CHF after myocardial infarction.

METHODS

Male Wistar rats were subjected to myocardial infarction by left coronary ligation. Subsequently, 24 h after surgery captopril (2.5 mg/kg/day/28 days) or losartan (3 mg/kg/day/28 days) was administered by mini-osmotic pump release. Hemodynamics, infarct size, and heart morphometry were measured in sham, untreated, and treated operated rats.

RESULTS

Morphometric and hemodynamic parameters were modified after myocardial infarction indicating hypertrophy of the heart and CHF establishment; however, either captopril or losartan partially avoided hypertrophy. Captopril reverted hemodynamics to sham values, while losartan induced further decrease in systolic blood pressure. Both drugs were able to drastically reduce infarct size produced by myocardial infarction.

CONCLUSIONS

Data show that early and chronic therapy with low doses of captopril or losartan prevent CHF establishment, probably by limiting extension of infarcted area after coronary occlusion, and suggest AT1 receptor pathway involvement in this pathology.

Pharmacologic Blockade of the Renin-Angiotensin System: Vascular Benefits Beyond Commonly Understood Pharmacologic Actions

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) are recognized primarily for their use in hypertension, in heart failure, and after myocardial infarction. New evidence, particularly with ACE inhibitors, has shown their ability to reduce acute coronary events associated with atherosclerosis in patients without a history of the aforementioned cardiac conditions. This is likely due to inhibitory effects on the renin-angiotensin system--a system that adversely influences fibrinolytic balance, vascular endothelial function, and vascular inflammation, all key components of atherosclerotic progression and adverse coronary outcomes. Results of various studies suggest favorable effects of ACE inhibitors and ARBs on markers of these components, including effects on plasminogen activator inhibitor-1, endothelin-1, and nitric oxide by ACE inhibitors, and effects on vascular cell adhesion molecule-1 and C-reactive protein by ARBs. Although early evidence suggests that ACE inhibitors may provide a greater beneficial effect on some of these markers compared with ARBs, and that certain ACE inhibitors may provide greater vascular benefits than others, further investigation is required to verify such findings. Overall, understanding the distinct coronary vascular benefits of these agents will emphasize the importance of using them, particularly ACE inhibitors, to improve outcomes in patients with coronary atherosclerotic disease.

Effects of angiotensin II type 1 receptor antagonist on electrical and structural remodeling in atrial fibrillation

The purpose of the present study was to evaluate the effect of angiotensin II type 1 receptor (AT1R) antagonist on chronic structural remodeling in atrial fibrillation (AF).

BACKGROUND

We previously reported that an AT1R antagonist, candesartan, prevents acute electrical remodeling in a rapid pacing model. However, the effect of candesartan on chronic structural remodeling in AF is unclear.

METHODS

Sustained AF was induced in 20 dogs (10 in a control group and 10 in a candesartan group) by rapid pacing of the right atrium (RA) at 400 beats/min for five weeks. Candesartan was administered orally (10 mg/kg/day) for one week before rapid pacing and was continued for five weeks. The AF duration, atrial effective refractory period (AERP) at four sites in the RA, and intra-atrial conduction time (CT) from the RA appendage to the other three sites were measured every week.

RESULTS

The mean AF duration in the control group after five weeks was significantly longer than that with candesartan (1,333 +/- 725 vs. 411 +/- 301 s, p < 0.01). The degree of AERP shortening after five weeks was not significantly different between the two groups. The CT from the RA appendage to the low RA after five weeks with candesartan was significantly shorter than that in the control (43 +/- 14 vs. 68 +/- 10 ms, p < 0.05). The candesartan group had a significantly lower percentage of interstitial fibrosis than the control group (7 +/- 2% vs. 16 +/- 1% at the RA appendage, p < 0.001).

CONCLUSIONS

Candesartan can prevent the promotion of AF by suppressing the development of structural remodeling.

Drugs that interrupt the renin-angiotensin system should be among the preferred initial drugs to treat hypertension

The goal of antihypertensive therapy is to provide effective treatment that can be sustained lifelong, while lowering elevated blood pressure and preventing hypertensive end-organ damage and mortality. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II antagonists (AIIAs) control blood pressure as well as other available classes of antihypertensive drugs. The ACE inhibitors have been demonstrated to reduce the incidence of stroke, reverse left ventricular hypertrophy, and improve congestive heart failure symptomatology and mortality to a similar degree as diuretics and beta-adrenergic blockers. ACE inhibitors reduce postmyocardial infarction recurrence, improve congestive heart failure symptomatology and mortality, and slow the progression of glomerular renal disease. The AIIAs reverse left ventricular hypertrophy. Several of these agents have been shown to improve congestive heart failure symptomology and mortality, to reduce the occurrence of early atherosclerotic vascular disease, and to slow the progression of renal failure in type 2 diabetes mellitus nephropathy. One AIIA has reduced the incidence of end-stage renal disease in non-insulin-dependence diabetes mellitus nephropathy over 3 years. Ideally, antihypertensive therapy should maintain or improve the patients quality of life without creating side effects or adverse laboratory effects. Among the available nine classes of antihypertensive drugs, ACE inhibitors and the AIIAs come close to meeting the description of an ideal drug. AIIAs and ACE inhibitors, two classes of antihypertensive drugs that reduce the activity of the renin-angiotensin II system, should be among the preferred first-step drugs for the treatment of hypertension.

ACE inhibitors and ARBs in chronic heart failure: the established, the expected, and the pragmatic

ACE inhibitors have been shown to reduce mortality, reduce hospitalization, reduce symptoms, and increase exercise capacity in patients with heart failure and a large heart (low ejection fraction). The evidence is overwhelming. There are some subgroups of patients, such as the very elderly and those with a normal ejection fraction, where uncertainty still exists. The combination of a diuretic and an ACE inhibitor is currently the proper treatment of congestive heart failure; a beta-blocker should be added in selected patients. The evidence for the efficacy of ARB is less persuasive and, for the present, this class of drug should be prescribed only when an ACE inhibitor cannot be tolerated. The results of the trials emphasize an emerging problem in medicine, namely how to evaluate a new treatment that may be as efficacious as current therapy but with fewer side-effects. Proving equivalence in efficacy will be difficult, requiring large studies comparing new drugs with the best current treatment. The most common etiology of heart failure is coronary heart disease. If further studies provide more support for the idea that ACE inhibitors prevent ischemic episodes and delay the onset of heart failure, then a new indication for ACE inhibitors will be the prevention of heart failure.

Decreased facilitation by angiotensin II of noradrenergic neurotransmission in isolated mesenteric artery of rabbits with chronic heart failure

Both in human and in experimental heart failure (HF), the renin-angiotensin system and the sympathetic nervous system are activated. In a previous study a facilitatory action of angiotensin II (Ang II) was shown in the rabbit mesenteric artery, which was mediated via prejunctionally located Ang II type 1 (AT ) receptors. Very little is known about the effects of Ang II on sympathetic neurotransmission at the peripheral level in congestive heart failure (CFH). Accordingly, in the isolated mesenteric arteries obtained from rabbits with experimentally induced CHF, as well as in age-matched control rabbits, the effect of Ang II on contractions provoked by electrical field stimulation was investigated in the presence and absence of the AT receptor antagonist eprosartan. Additionally, to investigate a possible postjunctional facilitation, the effects of Ang II on alpha-adrenoceptor-mediated responses were studied using noradrenaline (NA). Lastly, the vasoconstrictor effects of Ang II were compared between HF rabbits and controls, by constructing concentration-response curves to Ang II. In control rabbits, Ang II 0.5 n caused an enhancement of stimulation-induced responses by a factor 3.2 +/- 0.5, 2.4 +/- 0.3, and 1.5 +/- 0.08, at 1, 2, and 4 Hz, respectively ( < 0.05 at all frequencies compared with vehicle). In rabbits with HF, the enhancement by Ang II (0.5 n ) amounted to a factor 2.1 +/- 0.2, 1.7 +/- 0.1, and 1.2 +/- 0.04, at 1, 2, and 4 Hz, respectively ( < 0.05 compared with vehicle at all frequencies). Accordingly, the enhancing effect of Ang II was more pronounced in the control group compared with rabbits with HF ( < 0.05 at each frequency). Eprosartan (1 nM -0.1 microM) could inhibit the facilitatory effects of Ang II in arteries from HF as well as from control rabbits. Contractile responses to exogenous NA (3 n -0.1 m ) were the same in HF rabbits and controls, and they were unaltered in the presence of Ang II 0.5 n Ang II (0.1 nM -1 microM) caused a concentration-dependent increase in contractile force, which was the same in HF rabbits and controls. From these findings it can be concluded that in rabbits with CHF as well as in control animals, Ang II facilitates the stimulation-induced vasoconstrictor responses via prejunctionally located AT receptors. The facilitating effect was decreased in vessels obtained from rabbits with CHF, whereas responses to exogenous Ang II were unchanged. These findings may be explained by downregulation or uncoupling of the prejunctional AT receptor.

Possible involvement of the adipose tissue renin-angiotensin system in the pathophysiology of obesity and obesity-related disorders

Angiotensin II (Ang II), acting on the AT1 and AT2 receptors in mammalian cells, is the vasoactive component of the renin-angiotensin system (RAS). Several components of the RAS have been demonstrated in different tissues, including adipose tissue. Although the effects of Ang II on metabolism have not been studied widely, it is intriguing to assume that components of the RAS produced by adipocytes may play an autocrine, a paracrine and/or an endocrine role in the pathophysiology of obesity and provide a potential pathway through which obesity leads to hypertension and type 2 diabetes mellitus. In the first part of this review, we will describe the production of Ang II, the different receptors through which Ang II exerts its effects and summarize the concomitant intracellular signalling cascades. Thereafter, potential Ang II-induced mechanisms, which may be associated with obesity and obesity-related disorders, will be considered. Finally, we will focus on the different pharmaceutical agents that interfere with the RAS and highlight the possible implications of these drugs in the treatment of obesity-related disorders.

Effects of losartan and captopril on mortality and morbidity in high-risk patients after acute myocardial infarction: the OPTIMAAL randomised trial. Optimal Trial in Myocardial Infarction with Angiotensin II Antagonist Losartan

BACKGROUND

ACE inhibitors attenuate the detrimental effects of angiotensin II, and improve survival and reduce morbidity in patients with acute myocardial infarction and evidence of heart failure or left-ventricular dysfunction. Selective antagonism of the angiotensin type 1 receptor represents an alternative approach to inhibition of the renin-angiotensin system. We did a multicentre, randomised trial to test the hypothesis that the angiotensin II antagonist losartan would be superior or non-inferior to the ACE inhibitor captopril in decreasing all-cause mortality in high-risk patients after acute myocardial infarction.

METHODS

5477 patients 50 years of age or older (mean age 67.4 years [SD 9.8]), with confirmed acute myocardial infarction and heart failure during the acute phase or a new Q-wave anterior infarction or reinfarction, were recruited from 329 centres in seven European countries. Patients were randomly assigned and titrated to a target dose of losartan (50 mg once daily) or captopril (50 mg three times daily) as tolerated. The primary endpoint was all-cause mortality. Analysis was by intention to treat.

FINDINGS

There were 946 deaths during a mean follow-up of 2.7 (0.9) years: 499 (18%) in the losartan group and 447 (16%) in the captopril group (relative risk 1.13 [95% CI 0.99-1.28], p=0.07). The results for the secondary and tertiary endpoints were as follows: sudden cardiac death or resuscitated cardiac arrest 239 (9%) versus 203 (7%), 1.19 (0.98-1.43), p=0.07, and fatal or non-fatal reinfarction 384 (14%) versus 379 (14%), 1.03 (0.89-1.18), p=0.72. The all-cause hospital admission rates were 1806 (66%) versus 1774 (65%), 1.03 (0.97-1.10), p=0.37. Losartan was significantly better tolerated than captopril, with fewer patients discontinuing study medication (458 [17%] vs 624 [23%], 0.70 [0.62-0.79], p<0.0001).

INTERPRETATION

Since we saw a non-significant difference in total mortality in favour of captopril, ACE inhibitors should remain first-choice treatment in patients after complicated acute myocardial infarction. Losartan cannot be generally recommended in this population. However, it was better tolerated than captopril, and was associated with significantly fewer discontinuations. Although the role of losartan in patients intolerant of ACE inhibition is not clearly defined, it can be considered in such patients.

Angiotensin II receptor antagonists in chronic heart failure: where do they fit?

Heart failure is a common and disabling condition with a dismal prognosis. Inhibition of the renin-angiotensin-aldosterone system (RAAS) with angiotensin converting enzyme (ACE) inhibitors has proven to be a valuable therapeutic strategy in this condition, with well-proven morbidity and mortality benefits. Nonetheless, ACE inhibitors provide incomplete blockade of the RAAS and also inhibit the degradation of bradykinin. Although increased levels of bradykinin may have haemodynamic advantages by contributing to vasodilatation, they may also be largely responsible for some of the adverse effects of ACE inhibitors. Angiotensin II (Ang II) receptor antagonists offer more complete blockade of the RAAS without the potentiation of bradykinin, and it was therefore hoped that they would provide even greater benefits for patients with heart failure. So far, much of the initial promise of the Ang II receptor antagonists in heart failure has not been realised. There has been no conclusive demonstration of their superiority to ACE inhibitors in their effects on morbidity and mortality, and their equivalence to ACE inhibitors has not been proven. The Ang II receptor antagonists have, however, proven to be better tolerated than ACE inhibitors and they are therefore likely to be a reasonable alternative for those patients with heart failure who cannot tolerate ACE inhibition. Recent evidence has indicated that the Ang II type 1 receptor antagonist valsartan is of value when used in patients already receiving either an ACE inhibitor or a beta-blocker, but has also suggested that giving all three drugs together is deleterious. Further evidence about the value of Ang II receptor antagonists in heart failure may be provided by further studies, of which several are currently ongoing.

Sodium tanshinone IIA sulfonate derived from Danshen (Salvia miltiorrhiza) attenuates hypertrophy induced by angiotensin II in cultured neonatal rat cardiac cells

Sodium tanshinone IIA sulfonate (STS), a derivative of tanshinone IIA, is isolated from the root of Salvia miltiorrhiza known as "Danshen." Although injection of S. miltiorrhiza extract and STS is used widely and successfully in clinics in China for treating cardiovascular diseases, the exact mechanism for its therapeutic basis is poorly understood. The present study was undertaken to characterize the effect of STS on angiotensin II-induced hypertrophy on cultured myocytes and cardiac fibroblasts (nonmyocytes) prepared from neonatal rat hearts. Angiotensin II (1nM) increased protein synthesis and surface area in myocytes, and DNA synthesis and cell number in nonmyocytes, respectively. Exposure of the myocytes to STS (5-80 microM) for 24hr produced no cytotoxicity as evaluated by the 3-[4,5-dimethylthiazol-2-yl]-3,5-diphenylformazan (MTT) assay. Although STS (10 microM) alone showed no effect on the growth of cultured cardiac cells, it markedly suppressed angiotensin II-induced enlargement of cells and [3H]phenylalanine incorporation, proceeding from the induction of immediate early gene (c-jun) expression in myocytes. Furthermore, STS prevented the rise in [Ca(2+)](i) mediated by angiotensin II in myocytes. In contrast, STS (10 microM) was without effect on hyperplasia and c-jun expression induced by angiotensin II in nonmyocytes. The present in vitro findings support the interpretation that STS is a substance that may be beneficial in protecting the myocardium against hypertrophy.

Pharmacokinetics of irbesartan are not altered in special populations

Studies were conducted to determine whether pharmacokinetics of irbesartan (IRBE), a potent, long-acting angiotensin (AT)-II receptor antagonist selective for AT-II type 1 receptor subtype, are altered in patients with renal impairment (RI), hepatic impairment (HI), or heart failure (HF) or by patient gender, age, or race. IRBE pharmacokinetics and blood pressure (BP) response in hypertensive (HT) children and adolescents were also studied. HI or RI (including end-stage renal disease requiring hemodialysis) had no effect on IRBE pharmacokinetics after single or repeated dosing. IRBE was not removed by hemodialysis. In patients with New York Heart Association class II or III HF, IRBE single-dose pharmacokinetics were not altered following either oral or IV administration. There were no clinically significant differences in IRBE pharmacokinetics between men and women, elderly and young, or black and white patients. No accumulation of IRBE occurred with repeated dosing in RI or HI patients or in HT men or women. In a pediatric study, IRBE pharmacokinetics were comparable between 6- to 12-year and 13- to 16-year age groups and to that previously determined for adult subjects receiving the same dose; accumulation of IRBE was minimal during multiple dosing. IRBE lowered BP in the pediatric population. Adverse event profile with IRBE was similar in all patient groups. Based on these pharmacokinetic and safety data, no dosage adjustments of IRBE are necessary for patients with RI, HI, or HF, or based on patient age, gender, or race. IRBE may be a treatment option for pediatric HT patients. The pharmacokinetic profile of IRBE and lack of necessary dosage adjustments in special populations suggest that IRBE is an excellent choice for management of hypertension across all patient groups.

Effects of enalapril and eprosartan on the renal vascular nitric oxide system in human essential hypertension

BACKGROUND

Experimental data in humans on the contribution of angiotensin-converting enzyme inhibitors and angiotensin II type 1 receptor blockers to the nitric oxide system of the renal vasculature are inconsistent. Enalapril and eprosartan, alone and in combination, were used to determine their short-term effects on the renal nitric oxide system and renal hemodynamics of human subjects with essential hypertension.

METHODS

Twenty male, white patients (27 +/- 1 years) with mild essential hypertension (143 +/- 11/95 +/- 6 mm Hg) were included in a double-blind, randomized, placebo-controlled, fourfold cross-over study with placebo, enalapril (20 mg/day), eprosartan (600 mg/day), or combination of both drugs (10 and 300 mg/day, respectively) each over a one week period followed by a two-week washout phase. After each study phase the glomerular filtration rate (GFR) and renal plasma flow (RPF) were determined. Basal nitric oxide synthesis of the renal vasculature was assessed by the decrease in RPF after inhibition of nitric oxide synthase with NG-monomethyl-L-arginine (L-NMMA; 4.25 mg/kg).

RESULTS

After one week of therapy, the combination therapy decreased casual blood pressure by 5 +/- 2/3 +/- 1 mm Hg versus placebo (P < 0.01). Neither enalapril alone (-2 +/- 2/1 +/- 2 mm Hg, NS vs. placebo) nor eprosartan alone (-1 +/- 1/0 +/- 2 mm Hg, NS vs. placebo) had a clear-cut significant effect on casual blood pressure. In the combination phase, RPF increased by 123 +/- 36 mL/min (P < 0.01). Neither enalapril alone (+59 +/- 46 mL/min, P = 0.21) nor eprosartan alone (+113 +/- 51 mL/min, P = 0.06) had a clear-cut significant effect on RPF. Changes of RPF induced by treatment correlated with the L-NMMA induced decrease in RPF in the combination (r = 0.70, P < 0.01) and eprosartan phase (r = 0.86, P < 0.001), but not in the enalapril phase (r = -0.44, P = 0.10). Renal vascular resistance was reduced by each active treatment with the most prominent reduction in the combination phase. GFR was unaffected by any treatment.

CONCLUSIONS

In contrast to the effects of either substance alone, a combination of half the dose of eprosartan with half the dose of enalapril had a prominent effect on renal perfusion. The effects of eprosartan on RPF are mediated, at least in part, by an increased bioavailability of nitric oxide in the renal vasculature.

Losartan treatment and left ventricular filling during volume loading in patients with dilated cardiomyopathy

BACKGROUND

Patients with mild heart failure show a reduction in preload reserve mechanism during volume expansion. At this time, the effects of volume expansion on left ventricular (LV) diastolic filling in this subset of patients have not been well characterized.

METHODS

We evaluated the effects of acute volume loading on Doppler parameters of LV filling in 10 healthy control subjects and in 12 patients with idiopathic dilated cardiomyopathy (DCM). In patients with DCM, the effects of losartan on diastolic adaptation to volume load were also investigated.

RESULTS

During volume loading, the healthy control subjects showed a decrease in isovolumic relaxation time (F = 5.3, P <.05) but an increase in the LV peak filling rate (F = 52.9, P <.001) and velocity time integral of both systolic (F = 72.8, P <.001) and diastolic (F = 4.6, P <.05) pulmonary venous flow. In patients with DCM, isovolumic relaxation time decreased more than in control subjects (F = 8.1, P <.01), and the deceleration time of the early mitral wave was reduced (F = 26.3, P <.001). Furthermore, the duration of pulmonary venous flow reversal exceeded that of mitral flow at atrial contraction (F = 28.5, P <.001). After treatment with losartan, the deceleration time of early mitral wave remained unchanged, and the duration of pulmonary venous flow reversal at atrial contraction did not exceed that of mitral flow; thus, a significant treatment effect was detectable (F = 5.6, P <.05; and F = 6.6, P <.05, respectively).

CONCLUSIONS

Control subjects respond to volume load with enhancement in early LV filling, whereas patients with DCM show an increase of LV filling pressure. Diastolic adaptation to volume load improves in patients with DCM after treatment with losartan.

Angiotensin type-1 receptor blockers in heart failure

Chronic heart failure is a common condition with a poor prognosis, usually associated with poor exercise tolerance and debilitating symptoms despite optimal modern therapy. Standard therapy includes diuretics, digoxin, angiotensin-converting enzyme inhibitors (ACEIs) and beta-blockers. Despite this, many patients remain symptomatic, and interest is high as to whether the angiotensin receptor blockers (ARBs) would offer further advantage to a patient already receiving quadruple therapy. In addition, some patients are intolerant of ACEIs, and for this group the ARBs seem a logical choice. This article reviews the evidence for the use of ARBs as a class in heart failure concentrating on clinical recommendations and clinical needs and evidence rather than purely on statistical issues of significance in trials. The trials to date have demonstrated clearly similar hemodynamic effects to those seen with ACEIs and variety of ancillary benefits such as improvements in endothelial function, anti-thrombotic effects, and effects on neurohormonal inhibition. There is consistent evidence of a preservation of exercise tolerance when patients with heart failure are crossed over from stable ACEI therapy, and when added to ACEIs exercise tolerance appears to increase with ARBs. In terms of major outcomes, the two largest trials, Elite-II and Val-Heft, demonstrate that angiotensin receptor blockers probably have a clinical role in improving mortality and morbidity as an alternative to ACEIs in those patients unable to tolerate these agents, which remain, however, the first choice in unselected patients with heart failure. There is a worrying suggestion of a negative interaction when ARBs are added to beta-blockers, which is a reason for caution in using the ARBs, not a reason not to use beta-blockers.

Therapeutic potential of angiotensin II receptor antagonists

The circulating renin-angiotensin system plays an important role in cardiovascular homeostasis. More importantly, the local tissue renin angiotensin plays a pivotal role in cell growth and remodelling of cardiomyocytes and on the peripheral arterial vasculature. In addition, the renin angiotensin system is related to apoptosis, control of baroreflex and autonomic responses, vascular remodelling and regulation of coagulation, inflammation and oxidation. The cardioprotective and vascular protective effects of the angiotensin receptive blockade appears to be related to selective blockade of the angiotensin II (A-II) Type I (AT(1)) receptors. However, there is now growing evidence showing that some of the effects of AT-II receptor blockers (ARBs) are related to the activation of the kinin pathways. This paper will review some of the recent mechanisms related to the cardiovascular effects of angiotensin and more specifically of ARBs. This paper will present the novel data on the role of ARB in the development of atherosclerosis, vascular remodelling, coagulation balance and autonomic regulation. Finally, the role of ARBs, used alone or in combination with ACE inhibitor in patients with heart failure, will be discussed.

Dose-dependent blockade of the angiotensin II type 1 receptor with losartan in normal volunteers

Losartan, an angiotensin II type 1 receptor (AT1) antagonist, was developed as a more specific alternative to angiotensin-converting enzyme (ACE) inhibitors. At a daily dose of 50 mg, losartan is currently evaluated in large outcome trials involving patients with hypertension and postmyocardial infarction. The current study evaluated the level and duration of blockade of a pressor response to angiotensin II by 50 and 150 mg of losartan, compared with 32 mg of candesartan. Eight normotensive volunteers were randomly assigned to a single dose of losartan 50 or 150 mg, candesartan 32 mg, or placebo. Subjects were re-randomized after a 2-week washout period to complete all four study arms. Radial artery systolic pressure response to exogenous angiotensin II was measured at 2, 6, 12, and 24 h after administration of drug. Losartan 50 mg reduced the pressure response to exogenous angiotensin II significantly only at 6 h. In contrast, candesartan and losartan 150 mg produced a greater reduction in the pressure response to angiotensin II throughout the 24-h period. This suppression was not paralleled by a reduction in resting systemic arterial pressure. Higher doses than 50 mg of losartan might be evaluated to elicit optimal clinical effects.

Medical management of mild-to-moderate heart failure before the advent of beta blockers

Clinical trials of beta blockers in heart failure have generally required that patients be receiving optimal drug therapy before randomization to the study medication. Therefore, because beta blockers are used in addition to conventional drug therapy, review of the standard drug therapy of mild-to-moderate heart failure before the advent of beta blockade is essential to understanding the role of beta blockers in the treatment of heart failure. The conventional medical management of systolic heart failure includes angiotensin-converting enzyme (ACE) inhibitors, which should be used as first-line therapy; diuretics, for the management of body fluid-volume excess; digoxin; and some other vasodilators. These therapies have been evaluated in large-scale, randomized, controlled trials. ACE inhibitors have been shown to significantly attenuate disease progression and improve outcome (ie, morbidity and mortality) in patients with mild-to-moderate systolic heart failure. Controversial or unproven therapies include nonglycoside inotropic agents, angiotensin II receptor antagonists, antiarrhythmic agents, anticoagulants, and calcium channel blockers. The pharmacologic management of diastolic heart failure is largely empirical and is directed at reducing symptoms. Symptoms caused by increased ventricular filling pressures may be treated with diuretics and long-acting nitrates. Some calcium channel blockers and most beta blockers prolong diastolic filling time by slowing heart rate, thereby potentially improving the symptoms of diastolic heart failure. Calcium antagonists, beta blockers, diuretics, and ACE inhibitors may also promote regression of left ventricular hypertrophy and thus improve ventricular compliance, possibly preventing the development of diastolic dysfunction. Because randomized controlled trials of diastolic heart failure are lacking, this review focuses on the conventional management of mild-to-moderate systolic heart failure before the advent of beta blockade.

Pharmacotherapy in congestive heart failure: Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in congestive heart failure: do they differ in their renal effects in man?

Angiotensin-converting enzyme (ACE) inhibitors are used in the management of a wide range of cardiovascular conditions, including congestive heart failure (CHF). Although the experimental evidence in support of their use in CHF is incontrovertible, their pattern of usage has failed to keep pace with the research findings. One factor that has fueled the hesitancy to use ACE inhibitors in CHF has been the concern that renal function might worsen upon their receipt. Although the glomerular filtration rate may decline when ACE inhibitor or angiotension receptor blocker therapy is started in CHF, in most cases it is not a reason to discontinue therapy other than temporarily. Although ACE inhibitors and angiotensin receptor blockers may differ theoretically in their renal effects, published information to date has not shown such a difference. (c)2001 by CHF, Inc.

ADEPT: Addition of the AT1 receptor antagonist eprosartan to ACE inhibitor therapy in chronic heart failure trial: hemodynamic and neurohormonal effects

BACKGROUND

Persistent activation of the renin-angiotensin-aldosterone-system (RAAS) is known to occur in patients with chronic heart failure (CHF) despite treatment with angiotensin-converting enzyme inhibitor (ACE) therapy. When added to ACE inhibitors, angiotensin II type 1 (AT1) antagonists may allow more complete blockade of the RAAS and preserve the beneficial effects of bradykinin accumulation not seen with AT1 receptor blockade alone.

METHODS

Thirty-six patients with stable New York Heart Association class II-IV CHF receiving ACE inhibitor therapy were randomly assigned in a double-blind manner to receive either eprosartan, a specific competitive AT1 receptor antagonist (400 to 800 mg daily, n = 18) or placebo (n = 18) for 8 weeks. The primary outcome measure was left ventricular ejection fraction (LVEF) as measured by radionuclide ventriculography, and secondary measures were central hemodynamics assessed by Swan-Ganz catheterization and neurohormonal effects.

RESULTS

There was no change in LVEF with eprosartan therapy (mean relative LVEF percentage change [SEM] +10.5% [9.3] vs +10.1% [5.0], respectively; difference, 0.4; 95% confidence interval [CI], -20.8 to 21.7; P =.97). Eprosartan was associated with a significant reduction in diastolic blood pressure and a trend toward a reduction in systolic blood pressure compared with placebo (-7.3 mm Hg [95% CI, -14.2 to -0.4] diastolic; -8.9 mm Hg [95% CI, -18.6 to 0.8] systolic). No significant change in heart rate or central hemodynamics occurred during treatment with eprosartan compared with placebo. A trend toward an increase in plasma renin activity was noted with eprosartan therapy. Eprosartan was well tolerated, with an adverse event profile similar to placebo, whereas kidney function remained unchanged.

CONCLUSIONS

When added to an ACE inhibitor, eprosartan reduced arterial pressure without increasing heart rate. There was no change in LVEF after 2 months of therapy with eprosartan.

Angiotensin receptor blockers and aldosterone antagonists in chronic heart failure

Prognosis in congestive heart failure is directly linked to neurohormonal activation. Angiotensin II through the activation of the renin angiotensin aldosterone system has been the principal focus therapy over the last 2 decades. New agents that target selective blockade of the angiotensin II receptor have been introduced in clinical trials for the treatment of heart failure. Aldosterone has been identified as a critically important neurohormone with direct detrimental effects on the myocardium. Aldosterone antagonists have been used in clinical trials to improve mortality in patients with chronic heart failure.

Formulating clinical strategies for angiotensin antagonism: a review of preclinical and clinical studies

Extensive animal studies and a growing number of human clinical trials have now definitively demonstrated the central role of the renin-angiotensin-aldosterone system in the expression and modulation of cardiovascular disease. In contrast to the original hypothesis, the benefits of angiotensin antagonism do not emanate from the antihypertensive effect alone. Subsequent extensive investigations of angiotensin blockade suggest that the benefits of this approach may also result from the pharmacologic alteration of endothelial cell function and the ensuing changes in the biology of the vasculature. The more recent availability of direct antagonists of the AT(1) angiotensin receptor has introduced an element of doubt into this realm of clinical decision making. The receptor antagonists and the more widely studied converting-enzyme inhibitors share many endpoint attributes. Nevertheless, the partially overlapping mechanisms of action for the two classes of angiotensin antagonists confer distinct pharmacologic properties, including side effect profiles, mechanisms of action, and theoretic salutary effects upon the expression of cardiovascular disease. The current review will attempt to contrast the biology of angiotensin converting-enzyme inhibition with angiotensin II receptor antagonism. A discussion of the differential effects of these drug classes on endothelial cell function and on the modulation of vascular disease will be utilized to provide a theoretic framework for clinical decision making and therapeutics.

New competition in the realm of renin-angiotensin axis inhibition; the angiotensin II receptor antagonists in congestive heart failure

OBJECTIVE

To critically review the studies comparing angiotensin II (AgII) receptor antagonists with placebo or angiotensin-converting enzyme (ACE) inhibitors in patients with congestive heart failure (CHF).

DATA SOURCES

A MEDLINE search (1988 to January 2000) was used to identify pertinent literature. Additional references were also retrieved from selected articles.

STUDY SELECTION

As most published CHF studies were performed with candesartan and losartan, these agents are the main focus of this article. However, all identified comparative clinical studies were reviewed and included, regardless of the agent used.

DATA SYNTHESIS

AgII receptor antagonists inhibit the effects of AgII at its sub-type 1 receptor, independently of AgII's synthesis pathway. They present a hemodynamic profile similar to that of ACE inhibitors, without reflex neurohormonal activation. They have been shown to be at least as effective as ACE inhibitors in improving symptoms, exercise capacity, and New York Heart Association functional class in CHF patients. Although the ELITE (Evaluation of Losartan in the Elderly) trial suggested that losartan improved survival compared with captopril, this study was not designed to look at mortality. ELITE-II, an adequately powered study, showed no difference in mortality rates between patients taking captopril and those taking losartan. The combination of AgII receptor antagonists and ACE inhibitors provides additional benefit on blood pressure lowering and prevention of ventricular remodeling. AgII receptor antagonists are well tolerated, with an incidence of adverse effects similar to or lower than that of ACE inhibitors. Their lack of effect on bradykinin degradation might explain their lower incidence of cough.

CONCLUSIONS

The data cumulated thus far in patients with CHF highlight that ACE inhibitors must remain the treatment of choice and that AgII receptor antagonists may be considered as an acceptable alternative for patients who are intolerant to ACE inhibitors.

The role of the renin-angiotensin-aldosterone system in the management of heart failure

Numerous clinical trials have highlighted the role of the renin-angiotensin-aldosterone (RAA) system in the development and progression of heart failure. Over 30 randomized, controlled trials have evaluated the effects of angiotensin-converting enzyme (ACE) inhibitors on morbidity and mortality in over 7,000 patients with heart failure. Cumulative evidence from these trials shows that these agents significantly reduce mortality and hospitalizations, slow disease progression, and improve exercise tolerance and New York Heart Association class. The Heart Failure Society of America guidelines recommend ACE inhibitors as standard therapy for patients with left ventricular systolic dysfunction. The angiotensin receptor blockers and spironolactone offer alternative and perhaps complimentary mechanisms by which the RAA system may be therapeutically manipulated. The role of these therapies in treating heart failure is discussed.

Combined treatment with losartan and an ACE inhibitor in mild to moderate heart failure: results of a double-blind, randomized, placebo-controlled trial

BACKGROUND

Although the beneficial effects of angiotensin-converting enzyme (ACE) inhibitors in patients with heart failure are well recognized, there are theoretical advantages in combining ACE inhibition with angiotensin (AT)1 receptor antagonism.

METHODS

Twenty patients with mild to moderate heart failure and maximally treated with an ACE inhibitor were randomly assigned to losartan or placebo. Patients underwent repeated assessment of exercise tolerance, quality of life, central and regional hemodynamics, and neurohumoral and biochemical parameters over a period of 12 weeks.

RESULTS

Losartan treatment was well tolerated in terms of adverse events, heart rate, and blood pressure response, and there were no significant changes in serum creatinine or potassium. After 12 weeks of treatment, no significant differences were observed between the losartan and placebo groups in exercise tolerance, quality of life, central and regional hemodynamics, or neurohumoral parameters.

CONCLUSIONS

In patients with mild to moderate heart failure already maximally treated with an ACE inhibitor, additional treatment with losartan is well tolerated, but we have not observed any significant improvement in exercise capacity, quality of life, central and regional hemodynamics, or neurohormones. Our data suggest that the combination of losartan with an ACE inhibitor does not offer any substantial advantages over treatment with an ACE inhibitor alone in these patients.

Effects of combined angiotensin II and endothelin receptor blockade with developing heart failure: effects on left ventricular performance

BACKGROUND

The goal of this study was to determine the comparative effects of angiotensin II type 1 (AT(1)) receptor inhibition alone, endothelin-1 (ET) receptor blockade alone, and combined receptor blockade on left ventricular (LV) function, contractility, and neurohormonal system activity in a model of congestive heart failure (CHF).

METHODS AND RESULTS

Pigs were randomly assigned to each of 5 groups: (1) rapid atrial pacing (240 bpm) for 3 weeks (n=9), (2) concomitant AT(1) receptor blockade (valsartan, 3 mg/kg per day) and rapid pacing (n=8), (3) concomitant ET receptor blockade (bosentan, 50 mg/kg BID) and rapid pacing (n=8), (4) concomitant combined AT(1) and ET receptor inhibition and rapid pacing (n=8), and (5) sham-operated control (n=9). LV stroke volume was reduced from the control value after rapid pacing, was unchanged with either AT(1) or ET receptor blockade alone, but was improved with combination treatment. LV peak wall stress was reduced in both groups with ET receptor blockade compared with the rapid pacing group. Plasma norepinephrine levels were increased by >3-fold after rapid pacing, remained increased in the monotherapy groups, but were reduced after combination treatment. LV myocyte velocity of shortening was reduced after rapid pacing-induced CHF, remained reduced after AT(1) receptor blockade, increased after ET receptor blockade (compared with rapid pacing-induced CHF values), and returned to within control values after combined blockade.

CONCLUSIONS

Combined AT(1) and the ET receptor blockade in this model of CHF improved LV pump function, and contributory factors included the effects of LV loading conditions, neurohormonal system activity, and myocardial contractile performance. Thus, combined receptor blockade may provide a useful combinatorial therapeutic approach in CHF.

Cardiopulmonary events during hemodialysis: effects of dialysis membranes and dialysate buffers

Adverse cardiac and pulmonary events are frequently observed during hemodialysis and contribute to significant morbidity and mortality. The temporal relationship between these events during the intradialytic period has not been well defined. To examine the event rate and timing of silent ischemia, cardiac ectopy, and hypoxemia, we conducted a prospective, single-blind, randomized study of 10 subjects undergoing maintenance hemodialysis with four contiguous combinations of dialysis membranes (cuprammonium or polysulfone) and dialysates (acetate or bicarbonate). The frequency of oxygen desaturation events peaked during the first 2 hours, whereas silent myocardial ischemia and supraventricular ectopies occurred more often in the later hours. Ventricular ectopy occurred steadily throughout the intradialytic period. The combination of acetate dialysis and cuprammonium membrane is associated with the most frequent events. We conclude that cardiopulmonary events can occur frequently during hemodialysis, and the frequency is dependent on the type of dialysis membrane and dialysate buffer used.

Differential effects of direct antagonism of AII compared to ACE inhibitors on serum potassium levels and azotemia in patients with severe congestive heart failure

OBJECTIVES. The present study was undertaken to determine if direct blockade of angiotensin II receptors by losartan potassium as compared to ACE inhibition might result in greater tolerability in patients with congestive heart failure in whom ACE inhibition resulted in hyperkalemia and azotemia. BACKGROUND. Blockade of angiotensin II receptors by losartan potassium may produce similar benefits in congestive heart failure as ACE inhibition. However, some observations suggest losartan potassium may have different effects on renal function than ACE inhibition. METHODS. Five consecutive patients with severe congestive heart failure were identified in whom treatment with ACE inhibition was complicated by hyperkalemia (K>5.7) and azotemia. In three of these patients losartan potassium was substituted for ACE inhibition while losartan potassium was added to treatment with ACE inhibition in the remaining two. The mean of four serial values of potassium, blood urea nitrogen, and creatinine were compared before and after change in treatment using a two-tailed t test. RESULTS. The addition or substitution of losartan potassium resulted in statistically insignificant reductions in blood urea nitrogen and creatinine and a significant reduction in potassium from 5.7+/-0.1 to 4.9+/-0.3, p<0.03. Two patients who had required kayexalate were withdrawn. In all patients, hyperkalemia resolved and did not reoccur. CONCLUSIONS. There appear to be fundamental differences between the effects of losartan potassium and ACE inhibitors on potassium excretion in congestive heart failure patients with mild to moderate renal insufficiency. Losartan potassium may also be associated with less azotemia in such patients. These differences may have important clinical implications, particularly in the subset of patients in whom ACE inhibition is poorly tolerated as a result of hyperkalemia and azotemia. (c)2000 by CHF, Inc.

Effects of losartan and captopril on left ventricular volumes in elderly patients with heart failure: results of the ELITE ventricular function substudy

BACKGROUND

The mechanism by which angiotensin-converting enzyme inhibitors reduce mortality rates and disease progression in patients with heart failure is likely mediated in part through prevention of adverse ventricular remodeling. This study examined the effects of the angiotensin-converting enzyme inhibitor captopril and the angiotensin II type 1 receptor antagonist losartan on ventricular volumes and function in elderly patients with heart failure and reduced left ventricular ejection fraction (< or =40%).

METHODS

Patients underwent radionuclide ventriculograms (RVG) at baseline and were randomized to either captopril (n = 16) or losartan (n = 13). After 48 weeks, another RVG was obtained. Therapy was then withdrawn for at least 5 days, and the RVG was repeated while the patient was not receiving the drug.

RESULTS

At 48 weeks both captopril and losartan significantly reduced left ventricular (LV) end-diastolic volume index (135 +/- 26 to 128 +/- 23 mL/m(2) for losartan, P <.05 vs baseline; 142 +/- 25 to 131 +/- 20 mL/m(2) for captopril, P <.01; mean (SD). Captopril also reduced LV end-systolic volume index (98 +/- 24 to 89 +/- 21 mL/m(2), P <.01 vs. baseline), whereas a nonsignificant trend was observed for the losartan group (97 +/- 23 to 90 +/- 16 mL/m(2), P = not significant). The between-group differences in the changes in LV volumes were not statistically significant. After drug withdrawal, LV end-diastolic volume index remained significantly lower than baseline in the captopril group (P <.01).

CONCLUSIONS

Both captopril and losartan prevent LV dilation, representing adverse ventricular remodeling, previously seen with placebo treatment. Reverse remodeling was observed in the captopril group. On the basis of these results, the relative effects on LV remodeling do not provide a rationale for a survival benefit of losartan over captopril.

Reduction of plasma angiotensin II to normal levels by antisense oligodeoxynucleotides against liver angiotensinogen cannot completely attenuate vascular remodeling in spontaneously hypertensive rats

OBJECTIVE

The exact role of angiotensinogen (AGT) in vascular remodeling has yet to be determined. In the present study, we examined the effects of reducing plasma AGT by intravenous injections with antisense oligodeoxynucleotides (ODNs) against AGT targeted to the liver on vascular remodeling in spontaneously hypertensive rats (SHRs).

DESIGN AND METHODS

The ODNs against rat AGT were coupled to asialoglycoprotein (ASOR) carrier molecules, which serve as an important method for regulating liver gene expression. Male SHRs (n = 18) and age-matched male Wistar- Kyoto (WKY) rats (n = 4) were used for this study. All animals were fed a standard rat diet throughout the experiment At 10 weeks of age, the SHRs were divided into three groups (n = 6); systolic blood pressure (SBP) was similar in each group. The control group received saline, the sense group was injected with the sense ODN complex and the antisense group was injected with the antisense ODN complex. WKY rats were fed for the same period of time. The ASOR-poly(L)lysine-ODN complex was injected into the tail veins twice a week.

RESULTS

At the end of the treatment, a reduction in AGT mRNA levels in the liver and plasma AGT was observed only in the animals injected with antisense ODNs. Antisense ODNs significantly reduced the plasma angiotensin II (Ang II) concentrations to levels similar to those observed in WKY rats. Antisense ODNs significantly reduced the SBP (180.7 +/- 4.4 mmHg) and media cross-sectional areas of the aorta (1.11 +/- 0.02 mm2), which were still larger than those seen in WKY rats (140.3 +/- 2.1 mmHg, 0.84 +/- 0.02 mm2), compared with the SHRs injected with sense ODNs (225.2 +/- 4.4 mmHg, 1.24 +/- 0.02 mm2) and control SHRs (223.7 +/- 4.8 mmHg, 1.25 +/- 0.02 mm2). The aortic angiotensin-converting enzyme (ACE) activity and collagen concentrations, which were significantly higher than those seen in WKY rats, did not significantly change among the SHR groups. The aortic AGT, ACE, angiotensin II type 1 (AT1) receptor and angiotensin II type 2 (AT2) receptor mRNA also did not significantly change among the SHR groups.

CONCLUSION

On the basis of these findings, plasma AGT is thus considered to play a role in the development of hypertrophy of smooth muscle in the aorta of SHRs, it is thought to have only a slight effect, however, on the remodeling of the matrix tissue when the suppression of hypertension is insufficient.

Effect of losartan compared with captopril on mortality in patients with symptomatic heart failure: randomised trial--the Losartan Heart Failure Survival Study ELITE II

BACKGROUND

The ELITE study showed an association between the angiotensin II antagonist losartan and an unexpected survival benefit in elderly heart-failure patients, compared with captopril, an angiotensin-converting-enzyme (ACE) inhibitor. We did the ELITE II Losartan Heart Failure Survival Study to confirm whether losartan is superior to captopril in improving survival and is better tolerated.

METHODS

We undertook a double-blind, randomised, controlled trial of 3,152 patients aged 60 years or older with New York Heart Association class II-IV heart failure and ejection fraction of 40% or less. Patients, stratified for beta-blocker use, were randomly assigned losartan (n=1,578) titrated to 50 mg once daily or captopril (n=1,574) titrated to 50 mg three times daily. The primary and secondary endpoints were all-cause mortality, and sudden death or resuscitated arrest. We assessed safety and tolerability. Analysis was by intention to treat.

FINDINGS

Median follow-up was 555 days. There were no significant differences in all-cause mortality (11.7 vs 10.4% average annual mortality rate) or sudden death or resuscitated arrests (9.0 vs 7.3%) between the two treatment groups (hazard ratios 1.13 [95.7% CI 0.95-1.35], p=0.16 and 1.25 [95% CI 0.98-1.60], p=0.08). Significantly fewer patients in the losartan group (excluding those who died) discontinued study treatment because of adverse effects (9.7 vs 14.7%, p<0.001), including cough (0.3 vs 2.7%).

A pharmacokinetic and pharmacodynamic study of the potential drug interaction between tasosartan and atenolol in patients with stage 1 and 2 essential hypertension

The primary objective of this study was to evaluate the pharmacokinetics (PK) and pharmacodynamics (PD) of tasosartan and atenolol administered alone and concomitantly under steady-state conditions in 17 patients ages 18 to 65 years diagnosed with stage 1 to 2 essential hypertension. After a 3- to 14-day qualification period, all patients received placebo tasosartan on days--1 through 5 and 25 through 34, atenolol alone (50 mg) on days 1 through 5, atenolol (50 mg) + tasosartan (50 mg) on days 6 through 19, and tasosartan (50 mg) alone on days 20 through 24. A PK and PD evaluation of atenolol alone was performed on study day 5. On study day 19, PK and PD of both tasosartan and atenolol were assessed. PK and PD evaluation for tasosartan alone was assessed on study day 24. The coadministration of atenolol + tasosartan did not affect the pharmacokinetics of tasosartan, its major metabolite (enoltasosartan), or atenolol when compared with tasosartan or atenolol administered separately. For area under the change in diastolic blood pressure curve, the reduction was significantly greater after tasosartan + atenolol compared with that after atenolol alone (336 +/- 85 and 190 +/- 71 mmHg.24 h; p < 0.05 for combination and atenolol alone, respectively; mean +/- SEM). Combination therapy also caused a maximal reduction in diastolic blood pressure that is significantly more than with monotherapy with atenolol (-27 +/- 2 mmHg and -20 +/- 2 mmHg, respectively, p < 0.05). The additive effects of tasosartan and atenolol in decreasing diastolic blood pressure may provide a rationale for combination antihypertensive therapy.

Angiotensin II type 1 receptor antagonist decreases plasma levels of tumor necrosis factor alpha, interleukin-6 and soluble adhesion molecules in patients with chronic heart failure

OBJECTIVES

To evaluate the effects of an angiotensin (Ang II) type 1 receptor antagonist on immune markers in patients with congestive heart failure (CHF).

BACKGROUND

Ang II stimulates production of immune factors via the Ang II type 1 receptor in vitro, and the long-term effects of Ang II type 1 receptor antagonists on plasma markers of immune activation are unknown in patients with CHF.

METHODS

Twenty-three patients with mild to moderate CHF with left ventricular dysfunction were randomly divided into two groups: treatment with Ang II type 1 receptor (candesartan cilexetil) (n = 14) or placebo (n = 9). We measured plasma levels of immune factors such as tumor necrosis factor alpha (TNFalpha), interleukin-6 (IL-6), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1). We also measured plasma levels of the neurohumoral factors such as atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) and cyclic guanosine monophosphate (cGMP), a biological marker of ANP and BNP.

RESULTS

Plasma levels of TNFalpha, IL-6, sICAM-1 and sVCAM-1 were increased in the 23 CHF patients compared with normal subjects and significantly decreased after 14 weeks of candesartan cilexetil treatment, but did not change in the placebo group. Plasma levels of BNP, which is a marker of ventricular injury, significantly decreased, and the molar ratio of plasma cGMP to cardiac natriuretic peptides (ANP + BNP) was significantly increased after candesartan cilexetil treatment, but did not change in the placebo group.

CONCLUSIONS

These findings suggest that 14 weeks of treatment with an Ang II type 1 receptor antagonist (candesartan cilexetil) decreased plasma levels of the immune markers such as TNFalpha, IL-6, sICAM-1 and sVCAM-1 and that it improved the biological compensatory action of endogenous cardiac natriuretic peptides in patients with mild to moderate CHF.