Achieving Quality 24-h Blood Pressure Control with Candesartan Cilexetil

ACE-inhibitor, AT1-receptor-antagonist, or both? A clinical pharmacologist's perspective after publication of the results of ONTARGET

Clinical Pharmacology is commonly accepted to be a bridging discipline between basic science observations and clinical practice. Today, it should be a major task of the clinical pharmacologist in academia to provide support in the interpretation of preclinical and clinical study data, to develop evidence-based treatment guidelines and to serve as drug expert supporting all disciplines of clinical medicine with specific pharmacological and therapeutic knowledge. The results of the ONTARGET-trial confront both researchers and clinicians with the unexpected truth that AT(1)-receptor-blockade with an angiotensin-receptor-blocker (ARB) does not seem to have superior therapeutic benefit compared with an ACE-inhibitor (ACE-I) at reducing fatal and nonfatal cardiovascular events. The combination of the two drugs was associated with more adverse events without an increase in benefit. Therefore, the crucial question 'ACE-I, ARB, or both?' requires a new and critical appraisal depending on the medical indication for which these renin-angiotensin-system (RAS)-inhibitors are used: In a population of high-risk patients suffering from cardiovascular disease or diabetes mellitus, the evidence to favor an ARB over an ACE-I is still limited after ONTARGET and because of the higher costs for ARBs one can rather support the old therapeutic advice that ARBs are equally effective as ACE-Is and therefore therapeutic alternatives for patients with ACE-I intolerance. With respect to a very moderate additive BP-lowering effect of dual therapy with an ACE-I and an ARB seen in metaanalysis which was not even clearly attributable to dual RAS-inhibition and the increased adverse event rate in the combination treatment group of ONTARGET, this regimen seems not to be recommendable for the treatment of hypertension. Dual-RAS-blockade using an ACE-I-ARB-combination is an effective therapy to treat proteinuria and might be of therapeutic benefit especially in diabetic patients without concomitant diseases. There may be a therapeutic rationale to prefer ARBs over ACE-Is in well-selected patients with congestive heart failure (CHF) because a considerable amount of angiotensin II (Ang II) is produced independent of angiotensin-conversion-enzyme (ACE) in the failing heart and is therapeutically unaffected by ACE-I treatment. The results of the Val-HeFt and the CHARM-added-study revealed additive effects of an ARB on heart failure related morbidity and mortality when added to existing therapy with an ACE-I suggesting a role for ACE-I-ARB-combination treatment in well selected heart failure patients. Independent of the medical indication for its use, the concept of dual RAS-blockade with an ARB-ACE-I-combination should clinically be used with caution and a close monitoring of potassium levels and kidney function. Although the results of ONTARGET revealed equity of ramipril and telmisartan at reducing fatal and nonfatal cardiovascular events, we should not forget that pharmacologically not all ARBs are the same and the question if the study results of ONTARGET with telmisartan are transferable to the complete class of ARBs still merits further investigation.

Candesartan cilexetil--a review of effects on cardiovascular complications in hypertension and chronic heart failure

Therapeutic interventions that block the renin-angiotensin-aldosterone system (RAAS) have an important role in slowing the progression of cardiovascular risk actors to established cardiovascular diseases. In recent years, angiotensin receptor blockers (ARBs) have emerged as effective and well-tolerated alternatives to an angiotensin-converting enzyme inhibitor (ACEi) for RAAS blockade. The ARB candesartan was initially established as an effective once-daily antihypertensive treatment, providing 24-h blood pressure (BP) control with a trough:peak ratio close to 100%.

SCOPE

A Medline literature search was undertaken to identify randomised, controlled trials that examined the efficacy and cardiovascular outcomes associated with candesartan cilexetil in hypertension and chronic heart failure (CHF).

FINDINGS

Compared with other ARBs, candesartan demonstrates the strongest binding affinity to the angiotensin II type 1 receptor. Clinical trials have demonstrated that candesartan is well tolerated in combination with diuretics or calcium channel blockers (CCBs), making it a suitable treatment option for patients whose hypertension is not adequately controlled by monotherapy. Subsequently, candesartan became the only ARB licensed in the UK to treat patients with CHF and left ventricular ejection fraction < or = 40% as add-on therapy to an ACEi or when an ACEi is not tolerated. Studies in patients with symptomatic HF have indicated that candesartan treatment was associated with significant relative risk reductions in cardiovascular mortality and hospitalisation due to CHF.

CONCLUSIONS

There are clear indications that the clinical benefits of candesartan may extend beyond its proven antihypertensive effects to a wider range of complications across the cardiovascular continuum, including diabetes, left ventricular hypertrophy, atherosclerosis and stroke. Such results suggest that candesartan treatment may offer significant patient benefits as well as practical advantages over conventional treatment.

A large scale study of angiotensin II inhibition therapy in an elderly population: the CHANCE study

This 8-week, multicenter study evaluated the efficacy and safety of candesartan cilexetil (CC, 8-16 mg) in elderly (>65 years) hypertensive patients. Patients (n=3013) received CC 8 mg during 8 weeks which eventually doubled to CC 16 mg at week 4 if blood pressure remained uncontrolled (> or = 140/90 mmHg). At week 8, 65.5% of patients were normalized (BP < 140/90 mmHg). Mean changes at week 8 were -25.8, -13.2, and -12.7 mmHg for systolic, diastolic, and pulse pressure, respectively. Age, sex, and diabetic status did not influence the antihypertensive effect of CC. 68% of the patients treated with, but uncontrolled or intolerant of, prior antihypertensive treatment were normalized by CC 8-16 mg. In summary, CC 8-16 mg once daily was effective and well tolerated in the management of arterial hypertension in elderly subjects.

Inhibitory Effect of Candesartan Cilexetil on Left Ventricular Remodeling After Myocardial Infarction

Although angiotensin-converting enzyme inhibitors (ACEIs) have been shown to reduce left ventricular remodeling after acute myocardial infarction (AMI), the effects of angiotensin receptor blockers have yet to be established. This study was conducted to examine the effects of candesartan on left ventricular remodeling after AMI. Consecutive AMI patients were assigned to a candesartan group or ACEI group after successful coronary intervention. The patients in the candesartan group (n = 77, mean age, 62.8 +/- 1.3) received candesartan and the patients in the ACEI group (n = 80, mean age, 63.3 +/- 1.2) received lisinopril, enalapril, or trandolapril. Four mg was the most frequent dose in the candesartan group at 6 months. Lisinopril, enalapril, and trandolapril were administered to 52%, 27%, and 21% of the patients in the ACEI group, respectively. No significant differences in the incidences of cardiac death, nonfatal MI, or hospitalization for heart failure (P = NS) were found between the groups. The candesartan group exhibited a somewhat higher percent increase in left ventricular ejection fraction and significantly lower percent increases in left ventricular end-diastolic volume index and left ventricular end-systolic volume index compared to the ACEI group (P < 0.05, P < 0.05, respectively). Candesartan is more effective than ACEI in preventing left ventricular remodeling after AMI.

Efficacy and safety of oral candesartan cilexetil in patients with congestive heart failure

BACKGROUND

Candesartan cilexetil is a new angiotensin II receptor blocker with a high affinity for the angiotensin II-subtype 1 receptor.

AIMS

This 6-month study examined the safety and efficacy of candesartan cilexetil, 8 mg once daily, to prevent the progression of congestive heart failure (CHF).

METHODS

This randomised, double-blind, placebo-controlled study enrolled 305 patients with CHF who were not receiving ACE inhibitor therapy. The composite primary efficacy endpoint was progression of CHF or addition or dose escalation of CHF medications. The secondary endpoints were incidence of cardiovascular events and changes in left ventricular function.

RESULTS

The study was prematurely terminated after the second interim safety analysis. The incidence of confirmed progression of CHF was significantly lower in the candesartan group (7.4%) than in the placebo group (22.2%), with a risk reduction of 66.7% and a risk difference of -14.8% (95% CI: -22.8 to -6.8%, P<0.001). Cardiovascular events were also significantly lower during treatment with candesartan than with placebo (10.8% vs. 22.9%) with a risk reduction of 52.8% and a risk difference of -12.1% (95% CI: -20.6 to -3.6%, P<0.01). The actively treated group had a significant improvement in hemodynamics. Candesartan cilexetil was well tolerated.

CONCLUSION

Candesartan cilexetil, 8 mg/day, significantly reduced the progression of CHF when compared with placebo.

Candesartan Antihypertensive Survival Evaluation in Japan (CASE-J) Trial of Cardiovascular Events in High-Risk Hypertensive Patients: Rationale, Design, and Methods

Hypertension continues to be a major public health issue in the world. To combat this problem, many anti-hypertensive drugs have been developed and proven effective at controlling blood pressure in the last half century. In recent decades, antihypertensive drugs have been shown to have cardiovascular benefits beyond the reduction of blood pressure, and the focus has shifted to clarification of these effects. Angiotensin II receptor antagonists and calcium channel blockers are the most widely used antihypertensive drugs in Japan. However, these two classes of drugs have not yet been compared with respect to their efficacy for treating cardiovascular events. The Candesartan Antihypertensive Survival Evaluation in Japan (CASE-J) trial described herein is a prospective, multicenter, randomized, open-label, active-controlled, 2-arm parallel group comparison with a response-dependent dose titration and blinded assessment of endpoints in high-risk hypertensive patients treated with either an angiotensin II receptor antagonist (candesartan cilexetil) or a third-generation calcium channel blocker (amlodipine besilate). The eligibility criteria in this study were 1) age between 20 and 85 years; 2) systolic blood pressure (SBP) > or = 140 mmHg in those below 70 years of age or > or = 160 mmHg in those above 70 years of age or diastolic blood pressure (DBP) > or = 90 mmHg on two consecutive measurements at clinic; and 3) at least one of the following high risk factors for cardiovascular events: a) SBP > or = 2180 mmHg or DBP > or = 110 mmHg on two consecutive visits, b) type 2 diabetes mellitus (fasting blood glucose > or = 126 mg/dl, casual blood glucose > or = 200 mg/dl, HbA1c > or = 6.5%, 2 h blood glucose on 75 g oral glucose tolerance test (OGTT) > or = 200 mg/dl, or current treatment with hypoglycemic therapy), c) history of cerebral hemorrhage, cerebral infarction, or transient ischemic attack until 6 months prior to the screening, d) left ventricular hypertrophy on either echocardiography or ECG, angina pectoris, or history of myocardial infarction until 6 months prior to screening, e) proteinuria or serum creatinine > or = 1.3 mg/dl, and f) symptoms of arteriosclerotic artery obstruction. The therapeutic goals of blood pressure control were set as follows: SBP < 130 mmHg and DBP < 85 mmHg for patients below 60 years of age, SBP < 140 mmHg and DBP < 90 mmHg for those in their 60s, SBP < 150 mmHg and DBP < 90 mmHg for those in their 70s, and SBP < 160 mmHg and DBP < 90 mmHg for those in their 80s. A total of 3,200 patients, equally allocated to each of the two treatment arms, were required based on a two-sided alpha level 0.05 and 90% power. The CASE-J is also the first study to employ the newly developed Automatic Bar Code Data-Capturing/Allocation, Booking & Trial Coding, Data Management (ABCD) system for data collection and management. Enrollment of patients started in September 2001 and ended in December 2002. Follow-up data will be collected every 6 months until December 2005. The CASE-J trial will provide important evidence on the comparative effectiveness of candesartan cilexetil and amlodipine besilate on cardiovascular morbidity and mortality among Japanese. In addition, the use of the ABCD system is expected to contribute to the development of more efficient data management systems for large-scale clinical trials.

Methodology to determine duration of action for antihypertensive drugs

OBJECTIVE

To review and comment on methods used to assess the duration of action of antihypertensive drugs.

DATA SOURCES

A MEDLINE search (1966-June 2000) using key terms such as trough-to-peak ratio and ambulatory blood pressure monitoring was conducted.

STUDY SELECTION

An article was considered for this review if it pertained to the assessment of the duration of action of antihypertensive drugs. Special attention was given to articles dealing with methodologic aspects.

DATA SYNTHESIS

Antihypertensive drugs with a long duration of action are thought to provide better therapeutic coverage against hypertensive complications compared with that of short-acting agents. Measuring blood pressure at the end of the dosing interval may be a way to assess the duration of action of a drug. However, the use of high doses of a short-acting agent to obtain sufficient effect when at trough concentrations can potentially cause dose-related adverse effects at the peak time, contributing to nonadherence to therapy and thus to adverse outcomes. To alleviate this problem, the US Food and Drug Administration (FDA) has conceptualized the trough-to-peak (T:P) ratio. Although this arithmetic index has since been widely used to characterize the duration and safety of blood pressure control achieved by antihypertensive agents, several methodologic flaws limit its interpretation in the clinic. Ambulatory blood pressure monitoring (ABPM) is a more reliable approach to assess the duration of action and outcome of antihypertensive therapy.

CONCLUSIONS

Different methodologic approaches exist to evaluate the duration of action of antihypertensive drugs. Although the T:P ratio has been suggested by the FDA, it is difficult to establish a fair comparison among various antihypertensive agents based solely on this index. Treatment evaluation based on ABPM may be preferable to those guided by T:P because ABPM is more reproducible and is now established as a predictor of cardiovascular risk.