Valsartan and atenolol in patients with severe essential hypertension

Efficacy and safety of valsartan in hypertensive Taiwanese patients: post-marketing surveillance study

OBJECTIVE

To evaluate the efficacy and safety of valsartan in Taiwanese patients with essential hypertension.

METHODS

This 12-week multi-center, open-label, observational, post-marketing surveillance study enrolled 2046 hypertensive patients who were prescribed valsartan 80 or 160 mg as monotherapy or in combination with other antihypertensives based on clinical judgment. The primary endpoint was the incidence rate of dizziness with valsartan 160 mg monotherapy or combination therapy at Week 4. Secondary endpoints included the blood-pressure-lowering efficacy and the overall safety and tolerability of valsartan at Weeks 4 and 12.

RESULTS

The monotherapy and combination groups had comparable baseline characteristics. At Week 4, monotherapy was found non-inferior to combination for incidence rate of dizziness (monotherapy, 9.25%; combination, 10%; difference in incidence of dizziness, 0.75%; 95% CI - 0.61% to 2.12%; non-inferiority margin, -1.33%;WaldTest approach). Greater blood pressure (BP) reduction was noted atWeek 12 than atWeek 4.The antihypertensive effect was greater with combination therapy and the 160-mg dose. BP control (systolic <140 mmHg or diastolic <90 mmHg) was achieved in 80-90% patients.Valsartan was well tolerated; most commonly reported adverse events included dizziness, headache, constipation and cough.

CONCLUSION

Valsartan is an effective treatment option for essential hypertension in Taiwanese patients.

Spectrum of antihypertensive therapy in South Asians at a tertiary care hospital in Pakistan

Background

Despite available guidelines on hypertension (HTN), use of antihypertensives is variable. This study was designed to ascertain frequency of patients on monotherapy and > 1 antihypertensive therapy and also to ascertain proportion of patients on diuretic therapy.

Methods

It was a crossectional study conducted on 1191 adults(age > 18 yrs)hypertensive patients selected by computerized International Classification of Diseases -9-coordination and maintenance (ICD-9-CM) presenting to a tertiary care hospital in Pakistan. Data on demographics, comorbids, type of antihypertensive drug, number of antihypertensive drug and mean duration of antihypertensive drug was recorded over 1.5 year period (2008-09). Blood pressure was recorded on admission. Primary outcome was use of combination therapy and secondary outcome was use of diuretic therapy.

Results

A total of 1191 participants were included. Mean age(SD) was 62.55(12.47) years, 45.3%(540) were males. Diabetes was the most common comorbid; 46.3%(551). Approximately 85% of patients had controlled hypertension. On categorization of anti hypertensive use into 3 categories;41.2%(491) were on monotherapy,32.2%(384) were on 2 drug therapy,26.5%(316) were on ≥3 drug therapy. Among those who were on monotherapy for HTN;34%(167) were on calcium channel blockers,30.10%(148) were on beta blockers, 22.80%(112) were on Angiotensin converting enzyme (ACE) inhibitors,12%(59) were on diuretics and 2.20%(11) were on Angiotensin receptor blockers(ARB). Use of combination antihypertensive therapy was significantly high in patients with ischemic heart disease(IHD)(p < 0.001). Use of diuretics was in 31% (369) patients. Use of diuretics was significantly less in patients with comorbids of diabetes (p 0.02), Chronic kidney disease(CKD)(p 0.003), IHD (p 0.001) respectively

Conclusion

Most patients presenting to our tertiary care center were on combination therapy. Calcium channel blocker is the most common anti hypertensive drug used as monotherapy and betablockers are used as the most common antihypertensive in combination. Only a third of patients were on diuretic as an antihypertensive therapy.

Combination therapy in hypertension: An update

Meticulous control of blood pressure is required in patients with hypertension to produce the maximum reduction in clinical cardiovascular end points, especially in patients with comorbidities like diabetes mellitus where more aggressive blood pressure lowering might be beneficial. Recent clinical trials suggest that the approach of using monotherapy for the control of hypertension is not likely to be successful in most patients. Combination therapy may be theoretically favored by the fact that multiple factors contribute to hypertension, and achieving control of blood pressure with single agent acting through one particular mechanism may not be possible. Regimens can either be fixed dose combinations or drugs added sequentially one after other. Combining the drugs makes them available in a convenient dosing format, lower the dose of individual component, thus, reducing the side effects and improving compliance. Classes of antihypertensive agents which have been commonly used are angiotensin receptor blockers, thiazide diuretics, beta and alpha blockers, calcium antagonists and angiotensin-converting enzyme inhibitors. Thiazide diuretics and calcium channel blockers are effective, as well as combinations that include renin-angiotensin-aldosterone system blockers, in reducing BP. The majority of currently available fixed-dose combinations are diuretic-based. Combinations may be individualized according to the presence of comorbidities like diabetes mellitus, chronic renal failure, heart failure, thyroid disorders and for special population groups like elderly and pregnant females.

Valsartan: more than a decade of experience

Valsartan is a nonpeptide angiotensin receptor antagonist that selectively blocks the binding of angiotensin II to the angiotensin II type 1 receptor. The efficacy, tolerability and safety of valsartan have been demonstrated in large-scale studies in hypertension, heart failure (HF) and post-myocardial infarction (MI). This review focuses on what was learned from the valsartan clinical research programme and other comparative trials published from 1997 to the present. Many studies have demonstrated the efficacy of valsartan in lowering blood pressure (BP) in a variety of patient populations (including elderly, women, children, obese patients, patients with diabetes mellitus, patients with chronic kidney disease [CKD], patients at high risk of cardiovascular [CV] disease, African Americans, Hispanic Americans and Asians) and in improving outcomes in CV disease and CKD. In hypertension, valsartan exhibits dose-dependent efficacy in reducing both systolic and diastolic BP over the once-daily dose range of 80-320 mg; doses as high as 640 mg/day have been studied and found to be efficacious and safe. BP control can be enhanced with a more consistent 24-hour BP-lowering profile by using single-pill, fixed-dose combination therapy with valsartan plus hydrochlorothiazide (HCTZ). The cardioprotective benefits of valsartan have been demonstrated in large-scale outcome trials and include significant reductions in CV morbidity and mortality in HF, following MI, and in patients with co-morbid hypertension and coronary artery disease and/or HF; reductions in HF hospitalizations; and reductions in the incidence of stroke. The magnitude of these effects is comparable with that demonstrated with angiotensin-converting enzyme (ACE) inhibitors; however, valsartan has a more favourable tolerability profile, with a significantly lower incidence of cough and only rare reports of angio-oedema, both class effects of ACE inhibitor use. Consistent with its angiotensin receptor-blocking effects, valsartan also reduces circulating levels of biochemical markers that are associated with angiotensin II-mediated endothelial dysfunction and CV risk (e.g. high-sensitivity C-reactive protein or oxidized low-density lipoprotein). Improvements in CKD with valsartan include statistically and clinically meaningful reductions in urinary albumin and protein excretion in patients with type 2 diabetes and in nondiabetic patients with CKD. In short-term studies, valsartan has improved or stabilized various indices of metabolic function in at-risk patients, including those with co-morbid hypertension, obesity and/or metabolic syndrome. Because of this, valsartan is being prospectively investigated for its ability to reduce the incidence of new-onset diabetes and provide cardioprotection in patients with impaired glucose tolerance. Valsartan and valsartan/HCTZ are well tolerated. In clinical trials, adverse events during valsartan treatment were similar to those occurring with placebo. The combination of valsartan/HCTZ was better tolerated than HCTZ alone. Valsartan is administered once daily for hypertension; doses are usually taken upon awakening. In patients with HF or MI, valsartan is administered twice daily.

Safety and tolerability of fixed-dose irbesartan/hydrochlorothiazide for rapid control of severe hypertension

This prospective, double-blind, multicenter trial compared the safety and tolerability of irbesartan/hydrochlorothiazide (HCTZ) fixed-dose combination therapy with irbesartan monotherapy in patients with severe hypertension (seated diastolic blood pressure (SeDBP) >or=110 mm Hg, mean BP 172/113 mm Hg at baseline). Patients were randomized 2:1 to 7 weeks' irbesartan/HCTZ 150/12.5 mg to 300/25 mg (n = 468) or irbesartan 150 mg to 300 mg (n = 227). The incidence of treatment-related adverse events (AEs) was similar with combination and monotherapy (11.3% and 10.1%), and most AEs were mild-to-moderate. The combined incidence of prespecified AEs was lower with irbesartan/HCTZ than with irbesartan (8.8% vs. 11.5%). There were no treatment-related serious AEs or deaths. At week 5, more patients achieved SeDBP < 90 mm Hg compared to irbesartan (47% vs. 33%; P = 0.0005). Despite more rapid and aggressive BP lowering, initial fixed-dose irbesartan/HCTZ demonstrated a comparable AE profile to irbesartan monotherapy in patients with severe hypertension.

Angiotensin II receptor blockers in congestive heart failure

The benefits of angiotensin-converting enzyme (ACE) inhibitors for the treatment of congestive heart failure (CHF) are well-established. A newer class of medications, angiotensin II receptor blockers (ARBs), may be a suitable replacement for ACE inhibitors as a result of a more complete inhibition of angiotensin II and better tolerability among patients. To examine the current literature on the efficacy and safety of ARBs in the setting of CHF, a Medline search was conducted of the English language literature for the years 1987 to 2005. Clinical trials that reported data on cardiac outcomes were reviewed. The earlier trials were direct ARB to ACE inhibitor comparisons (ELITE I and ELITE II). These studies indicated that ARBs do not confer an improvement in cardiac outcomes over ACE inhibitors. RESOLVD, Val-HeFT, and the 3 separate trials of the CHARM program investigated the addition of an ARB to standard therapy. The RESOLVD trial showed no significant differences in clinical events among ACE inhibitor, ARB, and their combination. Although no mortality benefit was evident in the Val-HeFT trial, a substantial reduction in CHF rehospitalizations was reported among patients who were not receiving ACE inhibitor therapy. The CHARM-Overall program demonstrated a significant benefit in cardiovascular death and hospital admissions for CHF with the addition of ARB to standard therapy, a benefit that was more pronounced in patients with depressed left ventricular ejection fraction. In the setting of CHF, rates of cardiac outcomes do not differ substantially between ARBs and ACE inhibitors. However, their combination may improve outcomes for patients with CHF.

Angiotensin II antagonists--therapeutic benefits spanning the cardiovascular disease continuum from hypertension to heart failure and diabetic nephropathy

BACKGROUND

The cardiovascular benefits of angiotensin II antagonists (AIIAs) have been evaluated not only in terms of their ability to lower blood pressure but also on their ability to prevent strokes, cardiac events, and target organ damage. This review summarizes the body of evidence-based data demonstrating the efficacy of AIIAs across the spectrum of cardiovascular disease.

METHODS

A PubMed/MEDLINE search of English-language articles (1990 to September 2005) was used to identify articles describing clinical studies, particularly outcome trials, or mechanisms of therapeutic action pertinent to the therapy of cardiovascular disease or nephropathy.

FINDINGS

The antihypertensive efficacy of AIIAs is apparent across a wide spectrum of hypertensive patients, including black and Asian patients and patients with isolated systolic hypertension. More importantly, large outcome-based studies have demonstrated the efficacy of AIIAs across the continuum of cardiovascular disease, including hypertension, heart failure, post-myocardial infarction, and diabetic nephropathy. The Losartan Intervention For Endpoint reduction in hypertension study (LIFE), Reduction of Endpoints in Non-insulin-dependent Diabetes Mellitus with the AII Antagonist Losartan (RENAAL), and the Irbesartan Type 2 Diabetic Nephropathy Trial (IDNT) indicate that AIIAs confer cardiovascular and renal protective effects beyond their ability to lower blood pressure. These bloodpressure independent protective benefits of AIIAs may arise not only by blocking the deleterious effects of AII mediated via the AT1-receptor but may also be due to beneficial molecule-specific effects. As a class, AIIAs are well tolerated with an overall adverse event profile generally comparable to placebo and superior to that typically seen with calcium channel blockers, ACE inhibitors, diuretics, and beta-blockers.

CONCLUSIONS

By utilizing the body of clinical trial evidence as a guide to rational prescribing of AIIAs, practitioners can expect to deliver clinical benefits to their patients in terms of survival, prognosis, and quality of life.

Valsartan: the past, present and future

Valsartan (Diovan) is a widely use angiotensin receptor blocker that prevents angiotensin II from binding to the subtype 1 receptor. Stimulation of the subtype 1 receptor is believed to mediate many of the deleterious effects accompanied by increased angiotensin II levels. Valsartan is effective in the treatment of hypertension, alone and in combination with hydrochlorothiazide. Valsartan is similarly as effective as angiotensin-converting enzyme (ACE) blockers following myocardial infarction accompanied with left ventricular dysfunction, and/or heart failure. For the treatment of congestive heart failure with left ventricular dysfunction, valsartan offers a reduction in mortality in patients not able to tolerate an ACE inhibitor and in combination with an ACE inhibitor, valsartan reduces morbidity (hospitalization for heart failure).

Valsartan in the treatment of hypertension

Valsartan is a widely used, efficacious and very well-tolerated antihypertensive agent. By specifically blocking the action of angiotensin II on the angiotensin Type 1 receptor, valsartan reduces unwanted effects of angiotensin II, such as aldosterone, vasopressin and endothelin secretion, vasoconstriction, diuresis, endothelial cell hyperplasia, mitogenesis, induction of growth factors and production of collagen. Valsartan has a simple pharmacokinetic profile and requires no metabolism to become active. The dose-related efficacy of valsartan has been clearly demonstrated and the tolerability profile is similar to placebo. Clinical trials in elderly patients show good efficacy and high responder rates with the same doses as in younger patients. Valsartan is available as 80-, 160- and 320-mg tablets, and also in the same doses in combination with hydrochlorothiazide, 12.5 or 25 mg. Availability varies between countries. Beyond the reduction of blood pressure, valsartan is indicated for use in several countries in patients with heart failure and in patients post myocardial infarction, based on the results of the large-scale Valsartan Heart Failure Trial and VALsartan In Acute myocardial iNfarcTion trials. Valsartan has also been shown, in the Valsartan Antihypertensive Long-term Evaluation trial, to reduce the risk of developing new-onset diabetes in hypertensive patients at high risk of cardiac events.

Combination angiotensin receptor blocker/hydrochlorothiazide as initial therapy in the treatment of patients with severe hypertension

Patients with severe hypertension are at high risk for cardiovascular events. The authors hypothesized that initial treatment with a combination angiotensin receptor blocker/diuretic agent would be safe and more effective than initial treatment with a single agent for these patients. In this 6-week, double-blind trial, 585 patients were randomized to losartan/hydrochlorothiazide or losartan as monotherapy and titrated as needed at 2-week intervals to reach goal blood pressure (<90 mm Hg). Almost twice as many patients achieved goal at the primary end point of 4 weeks on 50 mg losartan/12.5 mg hydrochlorothiazide vs. the losartan regimen (50-100 mg; p=0.002). Additionally, almost three times as many patients achieved goal blood pressures at 6 weeks (p<0.001). Adverse experiences on losartan/hydrochlorothiazide (43%) were significantly less than with the angiotensin receptor blocker alone (52.6%). This study confirmed the efficacy and tolerability of initial use of a fixed combination of losartan/hydrochlorothiazide vs. losartan without a thiazide.

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.

Treatment of hypertension with an angiotensin II-receptor antagonist compared with an angiotensin-converting enzyme inhibitor: a review of clinical studies of telmisartan and enalapril

BACKGROUND

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II (ATII)-receptor antagonists suppress the effects of ATII and are effective antihypertensive agents. However, the use of ACE inhibitors is sometimes associated with intolerable side effects (eg, cough, angioedema), and patients may develop a compensatory rise in ATII levels. ATII-receptor antagonists have tolerability profiles similar to that of placebo and inhibit the effects of ATII more completely by blocking the AT1 receptor.

OBJECTIVE

This review summarizes clinical studies comparing the efficacy and tolerability of the ATII-receptor antagonist telmisartan with the ACE inhibitor enalapril in patients with hypertension.

METHODS

Randomized, controlled clinical trials comparing telmisartan with enalapril in patients with primary hypertension were identified through a PubMed search of the English-language literature from 1998 through 2001 and from bibliographic data provided by the manufacturer of telmisartan.

RESULTS

In 2 randomized, double-blind, placebo-controlled trials (total number of patients, 647), telmisartan 40 or 80 mg/d was at least as effective as enalapril 20 mg/d for lowering blood pressure (BP) in patients with mild to moderate hypertension. An open-label, titration-to-response study involving 86 patients with severe hypertension found that telmisartan 80 to 160 mg/d was as efficacious as enalapril 20 to 40 mg/d. The antihypertensive effects of telmisartan 20 to 80 mg/d and enalapril 5 to 20 mg/d were comparable in 278 elderly patients (age > or = 65 years) with mild to moderate hypertension enrolled in a 26-week, double-blind, dose-titration study. A double-blind, titration-to-response study in 71 patients with moderate renal impairment and mild to moderate hypertension found equivalent reductions in BP with telmisartan 40 to 80 mg/d and enalapril 10 to 20 mg/d without any clinically relevant decline in renal function. Telmisartan tended to be better tolerated than enalapril in this study, with fewer patients experiencing treatment-related adverse events (8.9% vs 26.9%, respectively).

CONCLUSIONS

Based on the literature included in this review, telmisartan and enalapril produced comparable reductions in BP in a broad range of patients with hypertension. Telmisartan appeared to have a better tolerability profile.

Renoprotective benefits of RAS inhibition: from ACEI to angiotensin II antagonists

In landmark clinical trials, pharmacological inhibition of the renin-angiotensin system (RAS) with angiotensin-converting enzyme inhibitors (ACEIs) attenuated the decline in renal function associated with chronic renal disease (CRD). Hemodynamic and nonhemodynamic effects of angiotensin II (Ang II) attest to its central role in the pathogenesis of CRD. Angiotensin II subtype 1 receptor antagonists (AT1RA) differ from ACEI in their effects on the RAS and on bradykinin metabolism. Elevations in bradykinin levels associated with ACEI and stimulation of angiotensin subtype 2 receptors resulting from AT1RA may produce therapeutic effects unique to each class of drug. Nevertheless, in animal models of CRD, ACEI and AT1RA exert equivalent renoprotection, implying that their renoprotective effects result primarily from inhibition of Ang II-mediated stimulation of angiotensin subtype 1 receptors. Clinical data comparing ACEI and AT1RA therapy in renal disease are limited to short-term studies, which indicate that AT1RAs have equivalent effects to ACEI on the major determinants of CRD progression, namely blood pressure and proteinuria. AT1RAs were well tolerated, with side-effect profiles similar to placebo. Taken together, available evidence suggests that AT1RAs will share the renoprotective properties of ACEI in human CRD. Nevertheless, the results of long-term clinical trials are required before AT1RA can be recommended as an alternative to ACEI in renoprotective therapy.

Valsartan: a novel angiotensin type 1 receptor antagonist

Valsartan is a highly selective, orally available antagonist of the angiotensin Type 1 (AT1) receptor. It is indicated for treatment of mild to moderate essential hypertension. Experimental studies have confirmed the abolition or attenuation of angiotensin II (AII)-related effects, such as vasoconstriction, cell growth promotion and aldosterone release. In humans, valsartan is rapidly absorbed with maximal plasma concentrations occurring 1-2 h after oral administration. The elimination half-life comes to about 7-8 h, valsartan is metabolised to a negligible extent and most of the drug is excreted via the faeces. There is no dose adjustment required for patients with a creatinine clearance > 10 ml/min. The dose should not exceed 80 mg o.d. in patients with hepatic dysfunction, valsartan is not recommended for patients with severe hepatic dysfunction and/or biliary cirrhosis. At present, no clinically relevant pharmacokinetic drug interactions have been observed. Valsartan produces persistent blood pressure reductions in patients with mild to moderate hypertension, the recommended starting dose is 80 mg o.d. If required, the dose may either be increased to 160 mg o.d. or hydrochlorothiazide may be added. In comparison to other antihypertensive drugs valsartan therapy leads to similar blood pressure reductions, while exhibiting a favourable tolerability profile. Preliminary studies suggest beneficial effects in patients with hypertensive end-organ damage such as renal disease and left ventricular hypertrophy. Furthermore, the drug is evaluated for its efficacy in heart failure and patients post-myocardial infarction.

Renal artery stenosis as a cause of renal impairment: implications for treatment of hypertension and congestive heart failure

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Efficacy and safety of eprosartan in severe hypertension. Eprosartan Multinational Study Group

The efficacy of eprosartan, a highly selective, orally-active non-biphenyl, non-tetrazole, type 1 angiotensin II (AT1) receptor antagonist, was compared with that of the angiotensin-converting enzyme (ACE) inhibitor, enalapril, with the addition of hydrochlorothiazide (HCTZ) when necessary in patients with severe hypertension (sitting diastolic blood pressure [sitDBP] > or = 115 mmHg and < or = 125 mmHg). Patients (n = 118) were randomized into an 8-week, double-blind titration phase and were started on oral eprosartan 400 mg total daily dose, given b.i.d., or oral enalapril 10 mg total daily dose, given o.d. The dose of eprosartan was increased to 600 and 800 mg daily, given b.i.d., and that of enalapril to 20 and 40 mg daily, given o.d., at weeks 2 and 4 if sitDBP was > or = 90 mmHg. If blood pressure remained uncontrolled on maximum doses of eprosartan or enalapril at week 6, HCTZ 25 mg o.d. was added to the treatment regimen. Patients whose blood pressure was deemed medically acceptable by the investigator at week 8 entered a 2-week maintenance phase on the final dose used in the titration phase. The primary efficacy measure was the difference between treatments of the mean reduction from baseline in sitDBP at the end of the study. Eprosartan and enalapril caused a similar reduction in sitDBP at study endpoint. The mean change in sitDBP at the end of the study for the eprosartan group was -20.1 mmHg vs -16.2 mmHg for the enalapril group. However, eprosartan produced significantly greater decreases in both sitting and standing systolic blood pressure (sitSBP and staSBP, respectively) than enalapril. The mean decrease in sitSBP was 29.1 mmHg for eprosartan compared with 21.1 mmHg for enalapril (p = 0.025). The mean reduction in staSBP was 27.8 mmHg for eprosartan compared with 20.0 mmHg for enalapril (p = 0.032). At the end of the study, the response rate (sitDBP < 90 mmHg or decreased from baseline by at least 15 mmHg) was 69.5% in the eprosartan group and 54.2% in the enalapril group. The proportion of patients in each treatment group who required addition of HCTZ was similar. Eprosartan was well tolerated; the overall incidence of adverse events was comparable to that in the enalapril group. These results demonstrate that in patients with severe hypertension, eprosartan is well tolerated and may be more effective than enalapril in reducing systolic blood pressure.

Mechanism of action of angiotensin-receptor blocking agents

Angiotensin II is the most active hormone of the renin-angiotensin system. In humans, two angiotensin receptors have been identified: AT(1) and AT(2). In adults, most of the effects of angiotensin II are mediated by the AT(1) receptor; the function of the AT(2) receptor is not yet well established. Angiotensin II has both systemic and local paracrine effects. Increased activity of angiotensin II and stimulation of the AT(1) receptor have been linked to the development of several cardiovascular and renal diseases, including hypertension, heart failure, left ventricular hypertrophy, and diabetic nephropathy. Over the past two decades, angiotensin-converting enzymes have been used to manage these diseases. However, the side effects and less-than- maximum therapeutic effects of angiotensin-converting enzyme inhibitors, particularly in the decrease of mortality associated with congestive heart failure, have led to the development of AT(1)-receptor blockers.

Non-peptide angiotensin type 1 receptor antagonists in the treatment of hypertension

Angiotensin II (Ang II) acts at the cellular level on two receptor subtypes: the AT1 receptor which can be blocked by losartan and its analogues (the 'sartan family'), and the AT2 receptor that does not react with the above antagonists but which can be blocked by different compounds, such as PD123319. AT1 receptor blockade has proven to be a highly effective means of interference with the renin-angiotensin system (RAS) and hence of reducing high blood pressure. As a result of the terminal blockade of the RAS cascade, circulating Ang II levels tend to rise two- to threefold. The free access of such enhanced levels to uninhibited AT2 receptors may be clinically relevant, as argued in the present review. The most extensive experimental and clinical experience with AT1 receptor blockade so far has been obtained with the pioneer drug losartan, although major contributions have also been made on candesartan cilexetil, irbesartan and valsartan. All of these four drugs have been instrumental in substantial clinical trials, serving as sources of information in the clinically oriented part of this review. AT1 receptor blocking drugs generally provide a relatively gradual decrease in blood pressure, which is comparable to that obtained with conventional anti-hypertensive drugs. Clinical trials reveal an astounding lack of drug-related adverse effects, scoring even better than placebo in terms of frequencies and sometimes patterns. The trough/peak ratio on single dosages seems to have been mastered, particularly with the second generation of AT1 receptor blockers, as is evident from 24 h ambulatory blood pressure monitoring. Combination with low-dose thiazide regimens is well established. Intermediate endpoints (micro-albuminuria and left ventricular hypertrophy) appear to be controllable. Morbid cardiovascular sequelae are currently under study in comparison with beta- and calcium channel blockade.