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Query: UMLS:C0010200 (cough)
 23,843 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Angiotensin II receptor antagonists represent a new class of drugs that provide a site-specific blockade of the effects of angiotensin II. Losartan potassium, the first compound of this drug class, has recently become available in the United States. The clinical experience with angiotensin II receptor antagonists has demonstrated that these drugs are safe and efficacious for the treatment of hypertension and, possibly, congestive heart failure. Unlike with angiotensin-converting enzyme inhibitors, the incidence of cough observed with angiotensin receptor antagonists is similar to that with placebo. Although several angiotensin receptors have been characterized, the effects of losartan and other angiotensin receptor antagonists under development are selective for the angiotensin II type 1 receptor. Unlike angiotensin-converting enzyme inhibitors, angiotensin receptor antagonists do not inhibit bradykinin metabolism or enhance prostaglandin synthesis. The antihypertensive efficacy of the angiotensin receptor antagonists has been documented to be similar to that of angiotensin-converting enzyme inhibitors. If the findings of clinical studies corroborate the initial reports on efficacy and safety, it seems likely that the angiotensin receptor antagonists will be added to the list of drugs that have been deemed suitable for first-line therapy in the treatment of hypertension and congestive heart failure.
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PMID:Angiotensin II receptor inhibition. A new therapeutic principle. 882 49

The introduction of nonpeptide angiotensin II antagonists in clinical use has necessarily led to comparison with the various and clinically established angiotensin converting enzyme inhibitors. In essence, losartan, the first approved angiotensin receptor antagonist, has a clinical profile highly similar to that of the converting-enzyme inhibitors, although much higher doses are required but with the advantage of no dry cough. On the other hand, the emergence of the concept of inverse agonism on other receptor systems has led to the search for pathological situations mediated through constitutive receptor activity as well as antagonists with inverse agonistic properties on the angiotensin receptor. Basic research on angiotensin peptide antagonists has led to the identification of molecular characteristics that produce antagonism. The combination of these characteristics then led to angiotensin antagonists that possessed a long in vivo duration of action. Studies with angiotensin converting enzyme inhibitors and nonpeptide antagonists on animal models of post-angioplastic restenosis revealed that both classes of compounds have similar partial efficacy on the inhibition of neointima formation. A peptide antagonist produced on the rat carotid model a complete inhibition of neointima formation. This increased efficacy is now tentatively attributed to potential inverse agonistic activity of this peptide antagonist. This concept would give angiotensin antagonists therapeutic opportunities where convertase inhibitors should be ineffective.
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PMID:What can angiotensin antagonists do that converting-enzyme inhibition can't: the case of post-angioplastic restenosis. 894 74

1. The availability of orally active specific angiotensin receptor antagonists (AT1 antagonists) has opened new therapeutic choices and provided probes to test the specific role of the renin-angiotensin system in the pathogenesis of cardiovascular disease. 2. The data available so far suggest that the antihypertensive efficacy of angiotensin receptor antagonists is comparable to that of angiotensin-converting enzyme (ACE) inhibitors. This provides further evidence that this latter class of drugs exerts its effect mainly through blockade of the renin-angiotensin enzymatic cascade. As expected, the association of a diuretic exerts an equally strong additive effect to the antihypertensive efficacy of both classes of drugs. 3. The most common side effect of ACE inhibitors, dry cough, does not occur with AT1 antagonists, which confirms the long-held view that this untoward effect of the ACE inhibitors is due to renin-angiotensin-independent mechanisms. 4. Long-term studies with morbidity/mortality outcome results are needed, before a definite position can be assigned to this newcomer in the orchestra of modern antihypertensive drugs. Notwithstanding, this new class of agents already represents an exciting new addition to our therapeutic armamentarium.
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PMID:Experience with angiotensin II antagonists in hypertensive patients. 899 54

Whether any class of antihypertensive drugs has specific renoprotective effects above and beyond lowering of blood pressure is still debatable. The renin-angiotensin system (RAS) is both localized and has many actions within the kidney, on intrarenal hemodynamics, on the mesangial cell, as well as stimulating growth factors and cytokines. Angiotensin converting enzyme (ACE) inhibitors have been shown to ameliorate the progression of renal failure. How much of this beneficial effect is due to their hemodynamic effects, how much to non-hemodynamic effects and how much to their effects on bradykinin and other putative ACE substrates is still unclear. Experimentally it can be shown that inhibiting ACE but preventing the fall in systemic blood pressure by salt loading abolishes renoprotection. Bradykinin has been implicated in both the beneficial and the adverse effects of ACE inhibitors. Because of this and because ACE inhibitors may not provide complete blockade of the RAS, angiotensin receptor (AT1R) antagonists have been developed. Experimentally AT1R antagonists have been shown to reproduce most of the beneficial effects of ACE inhibitors. The experience in humans is more limited but they have been demonstrated to be efficacious in hypertension, to reduce proteinuria, and produce a favorable hemodynamic effect in congestive cardiac failure with a low incidence of adverse effects and without cough. Calcium channel blockers (CCB) also have additional properties that may provide renoprotection beyond lowering blood pressure. However, as the different types of CCB block different calcium channels their effects may differ substantially. The inconsistency of the data in the renoprotective effect of CCB may reflect these differences. Quantitatively probably the most important factor in preventing the progress of renal failure by antihypertensive drugs is strict control of blood pressure. Lowering blood pressure by drugs is most likely effective by both reducing physical and sheer stress damage, as well as turning off the signal for the activation and production of vasoactive peptides and cytokines.
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PMID:Comparison of renin-angiotensin to calcium channel blockade in renal disease. 940 14

A double-blind comparator study was performed in 528 hypertensive patients [baseline sitting diastolic blood pressure (SitDBP) 95-114 mmHg]. The primary objective was to compare the incidence of drug-related cough in patients treated with enalapril and eprosartan. This paper reports the results of 27 asymptomatic patients who were recruited into a single centre substudy of the multicentre trial and randomised to receive either eprosartan (200-300 mg b.i.d.) or enalapril (5-20 mg o.d.). Blood pressure (BP) reduction, left ventricular (LV) mass regression and change in coronary flow reserve (CFR) after 6 months' treatment with either eprosartan or enalapril were compared. At the end of the study, eprosartan and enalapril were found to have caused similar reductions in BP. There was an increase in CFR in the eprosartan group to 1.6 +/- 0.3 and a decrease in CFR in the enalapril group to 1.3 +/- 0.3. Neither value was significantly different from baseline although the difference between the two groups was significant (p = 0.05). By study endpoint, there was a significant reduction in LV mass in the enalapril group (p = 0.05), but not the eprosartan (p = ns) group. Further investigation of the effects of angiotensin receptor blockers on CFR and LV mass regression appear warranted.
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PMID:Effect of long-term eprosartan versus enalapril antihypertensive therapy on left ventricular mass and coronary flow reserve in stage I-II hypertension. Eprosartan Study Group. 1021 5

The effects of a new angiotensin receptor antagonist, eprosartan (200 or 300 mg b.i.d.) and enalapril (5-20 mg u.i.d.) on cough and blood pressure were compared in a 26-week, double-blind, randomised, parallel-group, multicentre, international study involving 528 patients with hypertension. Uptitration of doses was based on clinic blood pressure measurements during the first 12 weeks, after which hydrochlorothiazide (12.5-25 mg/day) could be added. The frequency and intensity of cough was assessed by a standardised questionnaire administered at each clinic visit. The primary end-point was the incidence of persistent, dry cough not due to upper respiratory infection; change in sitting diastolic blood pressure and overall incidence of cough were secondary end-points. During the first 12 weeks of double-blind therapy, enalapril treatment was associated with a 3.45-fold higher risk of definite cough (14/261 vs 4/259, P = 0.018). Overall cough incidence (from spontaneous reports from patients, or investigator's observation) was also more frequent with enalapril, as compared to eprosartan. Both agents reduced blood pressure significantly compared to baseline, although the eprosartan-treated group had a slightly higher response rate (defined as sitting diastolic blood pressure <90 mm Hg, or at least a 10 mm Hg reduction from baseline), both at end of titration (70.3% vs 62.6%, P < 0.05) and after 26 weeks (81.7% vs 73.5%, P= 0.018). These data suggest that, in unselected hypertensive patients, eprosartan is associated with less cough and a somewhat higher responder rate than enalapril.
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PMID:Double-blind comparison of eprosartan and enalapril on cough and blood pressure in unselected hypertensive patients. Eprosartan Study Group. 1040 92

The renin-angiotensin system plays a central role in the regulation of blood pressure through its primary effector hormone angiotensin II. Studies conducted nearly 30 years ago with peptidic angiotensin II receptor blockers (ARB) suggested that disruption of the renin-angiotensin system offered considerable promise for the treatment of hypertension as well as heart failure. This promise was initially realized with the advent of angiotensin converting enzyme inhibitors, and more recently with nonpeptidic ARB that selectively antagonize the AT1-angiotensin receptor subtype. The potent and long-acting agent candesartan cilexetil illustrates how these new ARB fulfill the promises suggested by the early studies. Candesartan cilexetil provides a clinically relevant, dose-dependent reduction in diastolic and systolic blood pressure at doses of 4 to 16 mg once daily in patients with mild to moderate hypertension. Recent studies suggest that further blood pressure lowering is obtained with a 32-mg once daily dose. In comparative clinical trials, 8 mg of candesartan cilexetil and 10 to 20 mg of enalapril provided comparable antihypertensive effects. The safety and tolerability profile of candesartan cilexetil is comparable to placebo. Notably, this agent does not produce the dry, nonproductive cough that often limits use of angiotensin converting enzyme inhibitors, nor does it cause side effects that limit other antihypertensive drug classes. On the basis of the results of initial clinical studies, ARB also possess cardioprotective and renoprotective properties that promise to expand the role that these new agents will play in treating cardiovascular disorders.
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PMID:Update on the clinical pharmacology of candesartan cilexetil. 1067 85

Hypertension is a major problem throughout the developed world. Although current antihypertensive treatment regimens reduce morbidity and mortality, patients are often noncompliant, and medications may not completely normalize blood pressure. As a result, current therapy frequently does not prevent or reverse the cardiovascular remodeling that often occurs when blood pressure is chronically elevated. Blockade of the renin-angiotensin system (RAS) is effective in controlling hypertension and treating congestive heart failure. Both angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) inhibit the activity of the RAS, but these two classes of antihypertensive medications have different mechanisms of action and different pharmacologic profiles. Angiotensin-converting enzyme inhibitors block a single pathway in the production of angiotensin II (Ang II). In addition, angiotensin I is not the only substrate for ACE. The ACE inhibitors also block the degradation of bradykinin that may have potential benefits in cardiovascular disease. Bradykinin is, however, the presumed cause of cough associated with ACE inhibitor therapy. Data from clinical trials on ACE inhibitors serve to support the involvement of the RAS in the development of cardiovascular disease. Angiotensin receptor blockers act distally in the RAS to block the Ang II type 1 (AT1) receptor selectively. Thus, ARBs are more specific agents and avoid many side effects. Experimental and clinical trials have documented the efficacy of ARBs in preserving target-organ function and reversing cardiovascular remodeling. In some instances, maximal benefit may be obtained with Ang II blockade using both ARBs and ACE inhibitors. This review describes clinical trials that document the efficacy of ARBs in protecting the myocardium, blood vessels, and renal vasculature.
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PMID:Angiotensin receptor blockers: evidence for preserving target organs. 1128 62

Improvements in the death rate from coronary heart disease and in the control of hypertension have leveled off in recent years, reversing a trend toward steady improvement that began in 1972. Of the roughly 20% of Americans who suffer from hypertension, only 29% achieve adequate control (<140/90 mm Hg) with treatment and nearly half receive no treatment at all. Poor adherence to therapy doubtless plays a key role in this failure. As a major cause of poor adherence, tolerability becomes an extremely important element in any discussion of effective antihypertensive treatment. Despite their efficacy in treating hypertension, diuretics, beta-blockers, and calcium channel blockers have all been associated with numerous side effects, including increased serum lipid levels, insulin resistance, and edema. With the introduction of the angiotensin converting enzyme (ACE) inhibitors, patients were able to achieve blood pressure goals with fewer side effects. These agents, however, cause an irritating cough in up to 19% of patients. A newer class of drugs, the angiotensin receptor blockers (ARB), have similar effects to the ACE inhibitors, but their highly selective nature produces even fewer side effects. Eprosartan is a structurally unique ARB. Like the other ARB, this promising new agent has a side effect profile similar to placebo, and its response rate rivals or exceeds that of enalapril. Although it remains to be seen whether the ARB can significantly reduce morbidity and mortality from cardiovascular disease, preliminary data from the Evaluation of Losartan in the Elderly (ELITE) trial appear to be promising.
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PMID:Issues in hypertension: drug tolerability and special populations. 1145 11

Angiotensin II receptor antagonists (AAIIs) are the most specific inhibitors of the renin-angiotensin-aldosterone system. There are two types of angiotensin II (Ang II) receptors, the AT(1) receptor, which is responsible for all the classical physiological properties of Ang II, and the AT(2) receptor, whose function in humans remains unclear. The different AAIIs used in clinical practice vary depending on their pharmacodynamic and pharmacokinetic properties, and, for some of them, depending on their metabolism in vivo into an active metabolite. AAIIs are relatively well tolerated, and, unlike angiotensin-converting enzyme inhibitors (ACEIs), do not induce cough. AAIIs are indicated in mild, moderate and severe essential hypertension, where their efficacy has been proven in many studies. The maximal antihypertensive effect is obtained in a few days or weeks, and is somewhat retarded when compared with ACEIs. Their effect is independent of age and sex, but does depend to a certain extent on ethnic origin, since Afro-American patients are less sensitive to AAIIs than Caucasians. In general, the antihypertensive and haemodynamic response to blockers of the renin-angiotensin system is potentiated in presence of a negative salt balance and attenuated in case of a positive salt balance. This means that AAII efficiency is improved by salt depletion induced by a salt-free diet or thiazide diuretics. AAIIs induce short-term improvement of haemodynamic parameters in cardiac insufficiency. Several ongoing clinical trials have been designed to compare their efficacy in cardiac insufficiency and myocardial infarction with those of reference treatments. Valsartan has been recently shown to improve morbimortality in patients with cardiac insufficiency and receiving a conventional treatment including an ACEI. It has been convincingly shown that blockade of the renin-aldosterone system by ACEIs decreases proteinuria and slows down the progression of renal insufficiency, especially in type 2 diabetic nephropathy. Recent trials have shown that AAIIs share the same properties as ACEIs in these indications. It appears that the beneficial effect of AAIIs and ACEIs is not entirely explained by the blood pressure lowering effect of these drugs. AAII administration increases renin release and Ang II production, which may overcome Ang II blockade. On this basis, the combination of an AAII and an ACEI has been proposed to achieve a maximal renin-angiotensin system blockade. Several experimental studies in animals and preliminary clinical studies all indicate that the combination of the two drugs may be more beneficial than either drug used alone in hypertension, cardiac insufficiency and post-myocardial infarction. Clinical trials are necessary to further document the putative advantages of such a combined therapy. The future of AAIIs depends on the following: progress made in the understanding of the molecular and cellular activities of angiotensin (angiotensin receptor signalling, receptor dimerisation, presence of other angiotensin receptor subtypes, role of AT(2) receptor, etc.);a comprehensive view of the role of the local renin system in various organs (local generation and effect of Ang II on cellular proliferation, fibrosis, inflammation, angiogenesis, etc.);predictability of the response to AAII treatment (genetic predisposition to AAII treatment, in conjunction with environmental factors); andresults of the ongoing clinical trials designed to assess the long-term effects of AAIIs in cardiovascular mortality and morbidity, in comparison with reference treatments.
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PMID:[Angiotensin II receptor blockers: current status and future prospects]. 1203 89


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