ACE inhibitor- versus angiotensin II blocker-induced cough and angioedema

Angioneurotic edema

Angioneurotic edema is nonpitting edema involving the face, lips, tongue, larynx, and other locations. It may occur with use of angiotensin- converting enzyme inhibitors, vasopeptidase inhibitors, and, less frequently, angiotensin receptor blockers. Most episodes occur within the first 6 months of therapy. Predisposing factors for converting enzyme inhibitor angioedema include previous idiopathic angioedema, African American race, and transplant-related immunocompromise. Treatment is directed to preventing airway compromise. (c)2001 Le Jacq Communications, Inc.

The pharmacokinetics of irbesartan in hypertensive children and adolescents

An open-label study was conducted to characterize the pharmacokinetics and antihypertensive response to irbesartan in children (1-12 years) and adolescents (13-16 years) with hypertension. Patients received single once-daily oral doses of irbesartan 2 mg/kg (maximum of 150 mg once daily) for 2 to 4 weeks (+/- nifedipine or hydrochlorothiazide). Plasma irbesartan concentrations were determined by a validated high-performance liquid chromatography/fluorescence method from blood samples taken predose, up to 24 hours after dosing on Day 1, and up to 48 hours after the final dose. The plasma concentration-time profiles were similar between the 6- to 12-year and the 13- to 16-year age groups and to that previously determined from a study of adult subjects receiving approximately 2 mg/kg (i.e., 150 mg) oral irbesartan once daily. Mean reductions in systolic/diastolic blood pressure were 16/10 mmHg at Day 28 with irbesartan monotherapy (n = 8). Irbesartan was well tolerated and may be a treatment option for pediatric hypertensive patients.

Telmisartan plus hydrochlorothiazide versus telmisartan or hydrochlorothiazide monotherapy in patients with mild to moderate hypertension: a multicenter, randomized, double-blind, placebo-controlled, parallel-group trial

BACKGROUND

Recent surveys reveal continuing deficiencies in the awareness, treatment, and control of hypertension. In many cases, failure to achieve blood pressure targets may be attributable to the use of antihypertensive monotherapy.

OBJECTIVES

This study was undertaken to identify combinations of telmisartan, a new oral angiotensin II type 1-receptor antagonist, and hydrochlorothiazide (HCTZ) that might provide greater antihypertensive efficacy than monotherapy with either agent in the treatment of mild to moderate hypertension. It also examined the dose-response surface for the 2 drugs alone and in combination.

METHODS

This was a multicenter, randomized, double-blind, placebo-controlled, parallel-group study that employed all cells of a 4 x 5 factorial design. After a 4-week, single-blind, placebo run-in period, men and women between 18 and 80 years of age with mild to moderate hypertension (defined as mean supine diastolic blood pressure [DBP] between 95 and 114 mm Hg during the last 2 weeks of the placebo run-in period and systolic blood pressure [SBP] between 114 and 200 mm Hg immediately before randomization) were eligible to enter the 8-week, double-blind, double-dummy treatment period. Study comparisons were between once-daily telmisartan monotherapy (20, 40, 80, or 160 mg), HCTZ monotherapy (6.25, 12.5, or 25 mg), 12 combinations of these telmisartan/HCTZ doses, and placebo. The focus was on 2 combinations: telmisartan 40 mg/HCTZ 12.5 mg and telmisartan 80 mg/HCTZ 12.5 mg. The primary efficacy variable was change in supine trough DBP from baseline to the last evaluable measurement during double-blind treatment. Plasma renin activity and safety parameters, including treatment-emergent adverse events, physical findings, electrocardiograms, and serum electrolyte levels (which are known to increase with HCTZ treatment), were also assessed.

RESULTS

Of 1293 patients screened, 818 (63.3%) were enrolled at 47 centers. Of these 818, 749 (91.6%) completed the study. The intent-to-treat population (randomized with > or = 1 postrandomization blood pressure measurement) consisted of 807 patients (98.7%). Telmisartan 80 mg/HCTZ 12.5 mg significantly decreased mean supine trough SBP/DBP by 23.9/14.9 mm Hg, a benefit of 8.5/3.4 mm Hg compared with telmisartan 80 mg and of 17.0/7.6 mm Hg compared with HCTZ 12.5 mg (both comparisons, P < 0.01). Telmisartan 40 mg/HCTZ 12.5 mg significantly reduced mean supine SBP by 18.8 mm Hg, a benefit of 6.6 mm Hg compared with telmisartan 40 mg and 11.9 mm Hg compared with HCTZ 12.5 mg (both, P < 0.01). This same combination significantly reduced mean supine DBP by 12.6 mm Hg, a benefit of 5.3 mm Hg compared with HCTZ 12.5 mg (P < 0.01), but was not significantly different from telmisartan 40 mg. Telmisartan 80 mg/HCTZ 12.5 mg was significantly more effective than telmisartan 40 mg/HCTZ 12.5 mg in reducing mean supine DBP and SBP (both, P < 0.05). The response surface and responder analyses confirmed the additive antihypertensive efficacy of the combination of telmisartan and HCTZ. All regimens were well tolerated.

CONCLUSIONS

Once-daily telmisartan 80 mg/HCTZ 12.5 mg was effective and well tolerated when used to reduce SBP and DBP in patients with mild to moderate hypertension. In addition to enhancing efficacy, this combination protected against potassium depletion, a common side effect of thiazide monotherapy.

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.

Comparative study of effects of angiotensin II receptor antagonist, KD3-671, and angiotensin converting enzyme inhibitor, enalaprilat, on cough reflex in guinea pig

Angiotensin converting enzyme (ACE) inhibitor prevents the inactivation of bradykinin by inhibiting ACE activity, leading to side effects such as dry cough and angioedema. KD3-671 is a novel nonpeptide angiotensin II antagonist which is expected to exhibit persistent hypotensive action without these side effects. In this study, we investigated the relationship between the pharmacokinetics and cough-inducing effect of this drug in guinea-pig, compared with that of an ACE inhibitor, enalaprilat. KD3-671 was not significantly different from the vehicle treatment in the ability to induce coughing, whereas enalaprilat significantly enhanced coughing compared with the vehicle treatment. Thus, as expected from its mechanism of pharmacological action, KD3-671 did not induce coughing. We suggest that the citric acid-induced guinea pig coughing model will be useful in preclinical studies to examine the effect of drug on pulmonary function.

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.

A multicenter, randomized, double-blind study of the antihypertensive efficacy and tolerability of irbesartan in patients aged > or = 65 years with mild to moderate hypertension

BACKGROUND

Blockade of the renin-angiotensin-aldosterone system (RAAS) is the preferred mechanism of action for controlling hypertension in select groups of patients, including those with diabetic nephropathy and heart failure. Currently, 2 classes of drugs work by blocking the RAAS, albeit by differing mechanisms: angiotensin-converting enzyme (ACE) inhibitors and angiotensin II angiotensin type 1 receptor blockers (ARBs).

OBJECTIVE

The goal of this study was to assess the comparative efficacy and tolerability of the ARB irbesartan and the ACE inhibitor enalapril in patients > or = 65 years of age with mild to moderate hypertension (sitting diastolic blood pressure [DBP], 95 to 110 mm Hg).

METHODS

Elderly (> or = 65 years of age) patients were recruited from 26 Canadian study centers for a randomized, double-blind, 8-week clinical trial. Exclusion criteria included sitting DBP >110 mm Hg or sitting systolic blood pressure (SBP) >200 mm Hg, angina pectoris, myocardial infarction, cardiac procedure, stroke, or transient ischemic attack within 6 months of randomization, as well as other preexisting or present severe medical or psychologic conditions. Patients were randomly assigned to receive a single daily dose of irbesartan 150 mg (n = 70) or enalapril 10 mg (n = 71) with treatment doses of study drugs doubled at week 4 for sitting DBP > or = 90 mm Hg. Reductions from baseline blood pressure measurements at trough (24 +/- 3 hours after the last dose of medication) were assessed for sitting DBP and sitting SBP. Comparative tolerability to study drugs was also assessed.

RESULTS

The intent-to-treat analysis demonstrated similar reductions at week 8 in both DBP and SBP for both groups. For the primary efficacy analysis of sitting DBP, there was a mean reduction from baseline of 9.6 mm Hg and 9.8 mm Hg for the irbesartan and enalapril groups, respectively (P = 0.93). The mean reduction from baseline in sitting SBP was 10.1 mm Hg and 11.6 mm Hg for the irbesartan and enalapril groups, respectively (P = 0.54). Normalization rates (sitting DBP <90 mm Hg) at week 8 did not differ between groups (52.9% in the irbesartan group and 54.9% in the enalapril group; P = 0.81). No statistical difference existed between the 2 groups with respect to serious adverse events or discontinuations due to adverse events. Irbesartan was associated with a significantly lower incidence of cough than was enalapril (4.3% vs 15.5%, respectively; P = 0.046).

CONCLUSIONS

Irbesartan is an effective and well-tolerated antihypertensive for elderly patients with mild to moderate hypertension. This study establishes that irbesartan has better tolerability than enalapril with respect to cough and suggests that irbesartan is as effective at lowering blood pressure but better tolerated than an ACE inhibitor in hypertensive patients > or = 65 years of age.

Rationale for angiotensin II receptor blockers in patients with low-renin hypertension

African Americans outrank other ethnic groups in the United States in prevalence, early onset, and severity of hypertension. Furthermore, African Americans suffer the highest rates of mortality from cardiovascular, cerebrovascular, and end-stage renal disease. The recently concluded Heart Outcomes Prevention Evaluation (HOPE) study reports that the angiotensin-converting enzyme (ACE) inhibitor ramipril significantly reduced morbidity and mortality in a broad range of patients at high risk for cardiovascular events. These results strengthen the case for increasing the use of ACE inhibitor therapy. In accord with the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI) guidelines, antihypertensive monotherapy for African Americans is based on the known ability of diuretics and calcium channel blockers to produce greater reductions in blood pressure in this population than those attainable with beta blockers and ACE inhibitors. The national guidelines also suggest ACE inhibitors for all hypertensive patients with left ventricular dysfunction or nephropathy, which implies that African Americans must cross a clinical threshold to become candidates for these agents. The rationale for delaying ACE inhibitor therapy is due in part to a perceived unique pathobiology in hypertensive African Americans: an excess prevalence of salt sensitivity, hypervolemia, and low plasma renin activity (PRA). At first glance, it would seem intuitive to avoid agents that further depress the renin-angiotensin system (RAS) and choose agents that reduce plasma volume. However, most hypertensive African Americans are not hypovolemic. Furthermore, dietary sodium restriction and diuretic therapy raise PRA and improve the response to ACE inhibitors. The overall aim of this article is to explain the rationale for expanded use of drugs that block the RAS in African Americans and low-renin populations.

Therapeutic trials comparing angiotensin converting enzyme inhibitors and angiotensin II receptor blockers

Two independent pharmacologic methods of specifically interfering with the renin-angiotensin-aldosterone system have been brought to the marketplace: angiotensin converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs). These agents have the potential not only to be very widely used for a broad variety of clinical indications but also to compete against each other as treatments for hypertension, heart failure, renal impairment, and other conditions. Many short-term comparative studies of these two classes of drugs have now been completed. Most have focused on surrogate endpoints, such as blood pressure, renal function, or cough. These studies have generally concluded that ARBs are better tolerated but that the two drug classes otherwise have similar efficacy. The largest clinical trial comparing ARBs and ACE inhibitors thus far completed, Evaluation of Losartan in the Elderly (ELITE 2), failed to confirm the results of a smaller study; it did not demonstrate a significant improvement in outcomes (death or hospitalization for heart failure) with an ARB used alone, despite better tolerability. Many longer-term outcome studies with survival endpoints are under way, but most will compare the combination against an ACE inhibitor alone. These studies will define the optimal use of these agents in medicine for decades to come.

Pharmacologic Regulation of the Renin—Angiotensin System: Physiologic and Pathologic Effects

Objective:

To review the physiologic and pathologic roles of the renin-angiotensin system in maintaining blood pressure, glomerular filtration rate, and myocardial tissue growth. The pharmacologic regulations of the pathologic effects of the renin-angiotensin system are emphasized, with a comparison between angiotensin-converting enzyme (ACE) inhibitors and angiotensin1receptor (AT1) antagonists.

Data Sources:

English-language basic science, clinical studies, and review articles were identified using MEDLINE, IOWA, and a manual search from January 1966 through September 1999. References were also obtained from the reference section of relevant published articles.

Study Selection and Data Extraction:

All articles identified were evaluated for possible inclusion in this review. Evaluative and comparative data from basic science and controlled clinical studies were reviewed.

Data Synthesis:

The renin-angiotensin system has a plethora of physiologic and pathologic roles in the regulation of blood pressure, renal function, and cell growth. The cellular mechanisms involved in eliciting the responses to the renin-angiotensin system are discussed in detail, with an emphasis on the pharmacologic regulation of the cellular responses. The role of angiotensin II in maintaining blood pressure, glomerular filtration rate, and in regulating myocardial cell growth secondary to myocardial infarction or as a complication of congestive heart failure are all reviewed. The ACE inhibitors and AT1antagonists have comparable pharmacologic effects that can influence their therapeutic application. The ACE inhibitors and AT, antagonists are compared regarding clinically and experimentally observed differences that may affect their therapeutic application.

Conclusions:

The physiologic and pathologic roles of the renin-angiotensin system make the ACE inhibitors and AT1antagonists ideal candidates in treating many conditions. Presently, few studies have been conducted that directly compare ACE inhibitors and AT, antagonists. An understanding of the basic underlying pharmacologic principles is essential when attempting to apply the scientific and clinical information of the ACE inhibitors and AT1antagonists with the intention of extrapolating to therapeutic utility.

Risk-benefit ratio of angiotensin antagonists versus ACE inhibitors in end-stage renal disease

The effective treatment of hypertension is an extremely important consideration in patients with end-stage renal disease (ESRD). Virtually any drug class--with the possible exception of diuretics--can be used to treat hypertension in the patient with ESRD. Despite there being such a wide range of treatment options, drugs which interrupt the renin-angiotensin axis are generally suggested as agents of choice in this population, even though the evidence in support of their preferential use is quite scanty. ACE inhibitors, and more recently angiotensin antagonists, are the 2 drug classes most commonly employed to alter renin-angiotensin axis activity and therefore produce blood pressure control. ACE inhibitor use in patients with ESRD can sometimes prove an exacting proposition. ACE inhibitors are variably dialysed, with compounds such as catopril, enalapril, lisinopril and perindopril undergoing substantial cross-dialyser clearance during a standard dialysis session. This phenomenon makes the selection of a dose and the timing of administration for an ACE inhibitor a complex issue in patients with ESRD. Furthermore, ACE inhibitors are recognised as having a range of nonpressor effects that are pertinent to patients with ESRD. Such effects include their ability to decrease thirst drive and to decrease erythropoiesis. In addition, ACE inhibitors have a unique adverse effect profile. As is the case with their use in patients without renal failure, use of ACE inhibitors in patients with ESRD can be accompanied by cough and less frequently by angioneurotic oedema. In the ESRD population, ACE inhibitor use is also accompanied by so-called anaphylactoid dialyser reactions. Angiotensin antagonists are similar to ACE inhibitors in their mechanism of blood pressure lowering. Angiotensin antagonists are not dialysable and therefore can be distinguished from a number of the ACE inhibitors. In addition, the adverse effect profile for angiotensin antagonists is remarkably bland, with cough and angioneurotic oedema rarely, if ever, occurring. In patients with ESRD, angiotensin antagonists are also not associated with the anaphylactoid dialyser reactions which occur with ACE inhibitors. The nonpressor effects of angiotensin antagonists--such as an influence on thirst drive and erythropoiesis--have not been explored in nearly the depth, as they have been with ACE inhibitors. Although ACE inhibitors have not been compared directly to angiotensin antagonists in patients with ESRD, angiotensin antagonists possess a number of pharmacokinetic and adverse effect characteristics, which would favour their use in this population.

Spectrum of use for the angiotensin-receptor blocking drugs

The renin-angiotensin system (RAS) plays an important role in regulating blood pressure, and maintaining fluid and electrolyte balance. Angiotensin II is the principal mediator of the RAS and has been implicated in the development of hypertension as well as other forms of cardiovascular and renal disease. Angiotensin II-receptor antagonists are a new class of drugs that inhibit the RAS by selectively blocking the AT(1) receptor. These compounds therefore provide more specific and thorough blockade of the RAS by inhibiting the deleterious actions of angiotensin II at the receptor level, irrespective of how this peptide is formed. The increased specificity of action of angiotensin II-receptor antagonists may also circumvent unwanted side-effects normally associated with angiotensin-converting enzyme (ACE) inhibitors (eg, cough and angioedema) as these agents do not interfere with the metabolism of other peptides (eg, bradykinin, substance P, etc.). There is still some concern with angiotensin II-receptor antagonists and the long-term effects of hyper-stimulation of the unopposed AT(2) receptor that is caused by elevated levels of angiotensin II. However, it appears that stimulation of the AT(2) receptor may actually contribute to the beneficial effects of angiotensin II-receptor antagonists by counteracting the effects mediated by the AT(1) receptor. Angiotensin II-receptor antagonists display great therapeutic promise in the field of cardiovascular medicine and are currently being exploited as new antihypertensive agents. These drugs have demonstrated safety, efficacy, and tolerability; however, morbidity and mortality data are still lacking. Nonetheless, it is likely that angiotensin II-receptor antagonists will become part of the medical arsenal against cardiovascular and renal disease, thus consideration should be given to their future use as first-line antihypertensive agents.