Ramipril. A review of its pharmacological properties and therapeutic efficacy in cardiovascular disorders

Extemporaneous combination therapy with nebivolol/ramipril for the treatment of hypertension: a real-world evidence study in Europe

Objectives: To describe the clinical characteristics and treatment adherence in European adult hypertensive patients starting treatment with the extemporaneous combination of nebivolol and ramipril (NR-EXC).Methods: Retrospective database analysis of patients receiving NR-EXC treatment across five European countries (Italy, Germany, France, Poland, Hungary) over a period ranging from 3 to 9 years (until June 30, 2020) according to data availability for the different data sources. Patient demographics, comorbidities, and treatment adherence were evaluated.Results: We identified 592,472 patients starting NR-EXC. Most of them were over 60 years of age, with ramipril most commonly prescribed at 5 mg (from 30.0% to 57.2% of patients across the databases). Notable comorbidities included diabetes (19.2%) and dyslipidemia (18.2%). The study population was also highly subjected to polytherapy with antithrombotics, lipid-lowering agents, and other lowering blood pressure agents as the most co-prescribed medications, as resulted from Italian database. Up to 59% of the patients did not request a cardiologic visit during the study period. Adherence to therapy was low in 56.3% of the patients, and it was high only in 11.1% of them.Conclusions: The combination of nebivolol and ramipril is frequently prescribed in Europe, but adherence to treatment is suboptimal. The transition to a single pill combination could enhance treatment adherence and streamline regimens, potentially leading to significant benefits. Improved adherence not only correlates with better blood pressure control but also reduces the risk of cardiovascular events, underscoring the importance of this development.

Mechanisms for the development of heart failure and improvement of cardiac function by angiotensin-converting enzyme inhibitors

Angiotensin-converting enzyme (ACE) inhibitors, which prevent the conversion of angiotensin I to angiotensin II, are well-known for the treatments of cardiovascular diseases, such as heart failure, hypertension and acute coronary syndrome. Several of these inhibitors including captopril, enalapril, ramipril, zofenopril and imidapril attenuate vasoconstriction, cardiac hypertrophy and adverse cardiac remodeling, improve clinical outcomes in patients with cardiac dysfunction and decrease mortality. Extensive experimental and clinical research over the past 35 years has revealed that the beneficial effects of ACE inhibitors in heart failure are associated with full or partial prevention of adverse cardiac remodeling. Since cardiac function is mainly determined by coordinated activities of different subcellular organelles, including sarcolemma, sarcoplasmic reticulum, mitochondria and myofibrils, for regulating the intracellular concentration of Ca2+ and myocardial metabolism, there is ample evidence to suggest that adverse cardiac remodelling and cardiac dysfunction in the failing heart are the consequence of subcellular defects. In fact, the improvement of cardiac function by different ACE inhibitors has been demonstrated to be related to the attenuation of abnormalities in subcellular organelles for Ca2+-handling, metabolic alterations, signal transduction defects and gene expression changes in failing cardiomyocytes. Various ACE inhibitors have also been shown to delay the progression of heart failure by reducing the formation of angiotensin II, the development of oxidative stress, the level of inflammatory cytokines and the occurrence of subcellular defects. These observations support the view that ACE inhibitors improve cardiac function in the failing heart by multiple mechanisms including the reduction of oxidative stress, myocardial inflammation and Ca2+-handling abnormalities in cardiomyocytes.

Studies in Zebrafish Demonstrate That CNNM2 and NT5C2 Are Most Likely the Causal Genes at the Blood Pressure-Associated Locus on Human Chromosome 10q24.32

Background: Globally, high blood pressure (BP) is the most important risk factor for cardiovascular disease. Several genome-wide association studies (GWAS) have identified variants associated with BP traits at more than 535 chromosomal loci with genome-wide significance. The post-GWAS challenge is to annotate the most likely causal gene(s) at each locus. Chromosome 10q24.32 is a locus associated with BP that encompasses five genes: CYP17A1, BORCS7, AS3MT, CNNM2, and NT5C2 and warrants investigation to determine the specific gene or genes responsible for the phenotype. Aim: To identify the most likely causal gene(s) associated with BP at the 10q24.32 locus using zebrafish as an animal model. Results: We report significantly higher blood flow, increased arterial pulse, and elevated linear velocity in zebrafish larvae with cnnm2 and nt5c2 knocked down using gene-specific splice modification transcriptional morpholinos, compared with controls. No differences in blood-flow parameters were observed after as3mt, borcs7, or cyp17a1 knockdown. There was no effect on vessel diameter in animals with any of the four genes knocked down. At the molecular level, expression of hypertension markers (crp and ace) was significantly increased in cnnm2 and nt5c2 knockdown larvae. Further, the results obtained by morpholino knockdown were validated using zebrafish knockout (KO) lines with cnnm2 and nt5c2 deficiency, again resulting in higher blood flow, increased arterial pulse, and elevated linear velocity. Analysis of nt5c2a KO larvae demonstrated that lack of this gene resulted in reduced expression of cnnm2a, with reciprocal downregulation of nt5c2a in cnnm2a KO larvae. Staining of whole-blood smears from nt5c2 mutants revealed that KO of this gene might be associated with an acute lymphoblastic leukemia phenotype, consistent with literature reports. Additional experiments were designed based on previous literature on cnnm2a mutant zebrafish revealed impaired renal function, high levels of renin, and significantly increased expression of the ren gene, leading us to hypothesize that the observed elevated blood-flow parameters may be attributable to triggering of the renin-angiotensin-aldosterone signaling pathway. Conclusion: Our zebrafish data establish CNNM2 and NT5C2 as the most likely causal genes at the 10q24.32 BP locus and indicate that they trigger separate downstream mechanistic pathways.

Potential Therapeutic Options for COVID-19: Current Status, Challenges, and Future Perspectives

The COVID-19 pandemic represents an unprecedented challenge for the researchers to offer safe, tolerable, and effective treatment strategies for its causative agent known as SARS-CoV-2. With the rapid evolution of the pandemic, even the off-label use of existing drugs has been restricted by limited availability. Several old antivirals, antimalarial, and biological drugs are being reconsidered as possible therapies. The effectiveness of the controversial treatment options for COVID-19 such as nonsteroidal antiinflammatory drugs, angiotensin 2 conversion enzyme inhibitors and selective angiotensin receptor blockers was also discussed. A systemic search in the PubMed, Science Direct, LitCovid, Chinese Clinical Trial Registry, and ClinicalTrials.gov data bases was conducted using the keywords "coronavirus drug therapy," passive immunotherapy for COVID-19', "convalescent plasma therapy," (CPT) "drugs for COVID-19 treatment," "SARS-CoV-2," "COVID-19," "2019-nCoV," "coronavirus immunology," "microbiology," "virology," and individual drug names. Systematic reviews, case presentations and very recent clinical guidelines were included. This narrative review summarizes the available information on possible therapies for COVID-19, providing recent data to health professionals.

Analysis of Binding Interactions of Ramipril and Quercetin on Human Serum Albumin: A Novel Method in Affinity Evaluation

The aim of this study was to analyze the binding interactions between a common antihypertensive drug (ramipril, R) and the widely distributed plant flavonoid quercetin (Q), in the presence of human serum albumin (HSA). From the observed fluorescence spectra of the (HSA + R) system we can assume that ramipril is also one of the Site 3 ligands—similar to fusidic acid—the binding of which has been proven by RTG crystallography. Our claim is supported by near-UV CD spectroscopy, microscale themophoresis and molecular modeling. The presence of R slightly inhibited the subsequent binding of Q to HSA and, on the contrary, the pre-incubation of HSA with Q caused a stronger binding of R, most likely due to allosteric interactions. At high concentrations, R is also able to displace Q from its binding site. The dissociation constant K_D for the binding of R is more than hundredfold larger than for Q, which means that R is a very weak binder to HSA. The knowledge of qualitative and quantitative parameters of R, as well as the methods used in this study, are important for future research into HSA binding. This study shows the importance of implementing other methods for K_D determination. Microscale thermophoresis has proved to be a novel, practical and accurate method for K_D determination on HSA, especially in cases when fluorescence spectroscopy is unable to produce usable results.

Acute effects of angiotensin-converting enzyme inhibition versus angiotensin II receptor blockade on cardiac sympathetic activity in patients with heart failure

The beneficial effects of angiotensin-converting enzyme (ACE) inhibitors and angiotensin II (ANG II) receptor antagonists in patients with heart failure secondary to reduced ejection fraction (HFrEF) are felt to result from prevention of the adverse effects of ANG II on systemic afterload and renal homeostasis. However, ANG II can activate the sympathetic nervous system, and part of the beneficial effects of ACE inhibitors and ANG II antagonists may result from their ability to inhibit such activation. We examined the acute effects of the ACE inhibitor captopril (25 mg, n = 9) and the ANG II receptor antagonist losartan (50 mg, n = 10) on hemodynamics as well as total body and cardiac norepinephrine spillover in patients with chronic HFrEF. Hemodynamic and neurochemical measurements were made at baseline and at 1, 2, and 4 h after oral dosing. Administration of both drugs caused significant reductions in systemic arterial, cardiac filling, and pulmonary artery pressures (P < 0.05 vs. baseline). There was no significant difference in the magnitude of those hemodynamic effects. Plasma concentrations of ANG II were significantly decreased by captopril and increased by losartan (P < 0.05 vs. baseline for both). Total body sympathetic activity increased in response to both captopril and losartan (P < 0.05 vs. baseline for both); however, there was no change in cardiac sympathetic activity in response to either drug. The results of the present study do not support the hypothesis that the acute inhibition of the renin-angiotensin system has sympathoinhibitory effects in patients with chronic HFrEF.

Pharmacological and Clinical Profile of Moexipril: A Concise Review

Angiotensin-converting enzyme (ACE) inhibitors are effective and safe antihypertensive drugs, with the exception of the rare occasion of angioedema. These drugs have demonstrated additional cardiovascular protective effects to their blood pressure lowering, and their combination with the diuretic hydrochlorothiazide potentiates their antihypertensive effectiveness. Moexipril is a long-acting ACE inhibitor suitable for once-daily administration, and like some ACE inhibitors, moexipril is a prodrug and needs to be hydrolyzed in the liver into its active carboxylic metabolite, moexiprilat, to become effective. Moexipril alone and in combination with low-dose hydrochlorothiazide has been shown in clinical trials to be effective in lowering blood pressure and be well tolerated and safe given in single daily doses. In this review, the pharmacological profile of this drug and its clinical usefulness are discussed.

Zofenopril and incidence of cough: a review of published and unpublished data

OBJECTIVE

Cough is a typical side effect of angiotensin-converting enzyme (ACE) inhibitors, though its frequency quantitatively varies among the different compounds. Data on the incidence of cough with the lipophilic third-generation ACE inhibitor zofenopril are scanty and never systematically analyzed. The purpose of this paper is to give an overview on the epidemiology, pathophysiology, and treatment of ACE inhibitor-induced cough and to assess the incidence of cough induced by zofenopril treatment.

METHODS

Published and unpublished data from randomized and postmarketing zofenopril trials were merged together and analyzed.

RESULTS

Twenty-three studies including 5794 hypertensive patients and three studies including 1455 postmyocardial infarction patients exposed for a median follow-up time of 3 months to zofenopril at doses of 7.5-60 mg once-daily were analyzed. The incidence of zofenopril-induced cough was 2.6% (range 0%-4.2%): 2.4% in the hypertension trials (2.4% in the double-blind randomized studies and 2.4% in the open-label postmarketing studies) and 3.6% in the doubleblind randomized postmyocardial infarction trials. Zofenopril-induced cough was generally of a mild to moderate intensity, occurred significantly (P < 0.001) more frequently in the first 3-6 months of treatment (3.0% vs 0.2% 9-12 months), and always resolved or improved upon therapy discontinuation. Zofenopril doses of 30 mg and 60 mg resulted in significantly (P = 0.042) greater rate of cough (2.1% and 2.6%, respectively) than doses of 7.5 mg and 15 mg (0.4% and 0.7%, respectively). In direct comparison trials (enalapril and lisinopril), incidence of cough was not significantly different between zofenopril and other ACE inhibitors (2.4% vs 2.7%).

CONCLUSION

Evidence from a limited number of studies indicates a relatively low incidence of zofenopril-induced cough. Large head-to-head comparison studies versus different ACE inhibitors are needed to highlight possible differences between zofenopril and other ACE inhibitors in the incidence of cough.

Ramipril: a review of its use in preventing cardiovascular outcomes in high-risk patients

Ramipril is an oral, non-sulfhydryl ACE inhibitor thought to act in the renin-angiotensin-aldosterone system to decrease vasopressor activity, aldosterone secretion, and bradykinin degradation. Ramipril is generally well tolerated and effective in the treatment of patients aged > or =55 years at high risk for the development of cardiovascular (CV) events, in whom the risk of myocardial infarction (MI), stroke, and CV death can be significantly reduced. The risk of these CV outcomes may also be reduced with ramipril therapy in various subgroups; these include patients with diabetes mellitus, peripheral arterial disease (PAD) or renal insufficiency, and women. Thus, ramipril, in addition to lifestyle interventions, should be considered an important therapy in the prevention of CV outcomes in high-risk patients.

The renal antifibrotic effects of angiotensin-converting enzyme inhibition involve bradykinin B2 receptor activation in angiotensin II-dependent hypertension

OBJECTIVE

The renoprotective action of angiotensin I-converting enzyme inhibitors (ACE-Is) is well established, but the role played by bradykinin (BK) remains unclear. We therefore investigated whether an enhanced BK effect on B2 receptor subtype mediated the antifibrotic effect of ACE-Is and whether neutral endopeptidase (NEP) inhibition, which can blunt BK degradation more effectively than ACE inhibition, provided further renoprotection in a rat model of angiotensin (Ang) II-dependent renal damage.

METHODS

Five-week-old Ren-2 transgenic rats (TGRen2) received, for 8 weeks, a placebo, ramipril (5 mg/kg body weight) or the dual ACE + NEP inhibitor MDL 100,240 (MDL) (40 mg/kg body weight). After 4 weeks, the B2 receptor antagonist icatibant (0.5 mg/kg body weight) was administered on top of active treatment for 4 weeks to 50% of the TGRen2 rats. Blood pressure was measured weekly by a tail-cuff method and, after sacrifice, kidney weight, glomerular volume, density of glomerular profiles were measured; tubulo-interstitial fibrosis, glomerular and perivascular fibrosis were quantified by histomorphometry.

RESULTS

The development of hypertension and tubulo-interstitial fibrosis was prevented by both ramipril and MDL (P = 0.0001 versus placebo); icatibant annulled the latter effect. Glomerular and perivascular fibrosis were unaffected by either ramipril or MDL alone; however, combined treatment with icatibant enhanced glomerular fibrosis (P = 0.0001 versus placebo).

CONCLUSION

Enhanced BK effect on B2 subtype receptors is essential for the prevention of tubulo-interstitial fibrosis with ACE or dual ACE + NEP inhibition in TGRen2 rats.

Ramipril in the treatment of vascular diseases

Ramipril is an angiotensin-converting enzyme inhibitor that has been extensively studied in randomised, controlled clinical trials in patients with cardiovascular diseases. Therapy with ramipril in patients with various cardiovascular disorders has demonstrated significant and clinically important reductions in cardiovascular death, myocardial infarction, stroke, congestive heart failure, progressive renal impairment and onset of diabetes. Ramipril is usually dosed at 2.5-10 mg/day. Beneficial effects of ramipril are observed in the treatment of hypertension and congestive heart failure, prevention of cardiovascular events in high-risk patients, prevention of congestive heart failure, diabetes and other vascular events.

Pharmacological profile and clinical use of moexipril

Angiotensin-converting enzyme (ACE) inhibitors are effective and safe antihypertensive drugs with the exception of the rare occurrence of angioedema. These drugs have demonstrated additional cardiovascular protective effects to their blood pressure lowering and their combination with the diuretic hydrochlorothiazide potentiates their antihypertensive effectiveness. Moexipril (Univasc, Bayer) is a long-acting ACE inhibitor suitable for once-daily administration and, like enalapril, is a prodrug and needs to be hydrolyzed in the liver into its active carboxylic metabolite, moexiprilat, in order to become effective. Moexipril alone and in combination with low-dose hydrochlorothiazide has been shown in clinical trials to be effective in lowering blood pressure and to be well-tolerated and safe given in single daily doses. In this review, the pharmacological profile of this drug and its clinical usefulness will be discussed.

Spotlight on ramipril in the prevention of cardiovascular outcomes

Ramipril (Altace)Use of tradenames is for product identification purposes only and does not imply endorsement.), an angiotensin-converting enzyme (ACE) inhibitor, is a prodrug which is rapidly hydrolyzed after absorption to the active metabolite ramiprilat. Earlier trials have shown that ACE inhibitors, when given to patients with low ejection fractions, have reduced the relative risk of myocardial infarction (MI) and other ischemic events by 14-23%. Subsequently, the double-blind, randomized, placebo-controlled, multicenter Heart Outcomes Prevention Evaluation (HOPE) study has shown that, in patients who are not known to have low ejection fraction or heart failure but are at increased risk for developing cardiovascular events, ramipril reduced the incidence of stroke, MI and death due to cardiovascular disease. Results from the HOPE study, in which 9297 patients were randomized to receive either ramipril 10 mg/day or placebo for a mean of 4.5 years, indicate that ramipril reduced the relative risk of the composite outcome of MI, stroke and cardiovascular death by 22%. The incidence of the composite outcome was significantly lower in the ramipril group than in the placebo group (14.0% vs 17.8%). Patients who received ramipril, compared with placebo recipients, had a significantly decreased incidence of stroke, MI or death due to cardiovascular disease (3.4% vs 4.9%, 9.9% vs 12.3% and 6.1% vs 8.1%, respectively). The relative risk of death from any cause was reduced among patients who received ramipril. In addition, treatment with ramipril reduced as the incidence of revascularization procedures, and, among patients with diabetes mellitus, ramipril reduced the incidence of complications related to diabetes mellitus, including the development of overt nephropathy. Moreover, in patients without a previous diagnosis of diabetes mellitus, ramipril, compared with placebo, significantly reduced the development of diabetes mellitus. Furthermore, compared with patients receiving placebo, patients receiving ramipril had a reduced rate of progression of carotid artery wall thickness.

CONCLUSION

Ramipril 10 mg/day can significantly reduce the incidence of MI, stroke or death from cardiovascular causes in patients aged > or =55 years who are at increased risk for the development of ischemic cardiovascular events due to a history of stroke, coronary artery disease (with controlled blood pressure), diabetes mellitus plus at least one other risk factor or peripheral vascular disease but no heart failure or low ejection fraction. Therefore, in addition to dietary and lifestyle modifications, ramipril should be an integral part of secondary prevention therapy in patients at increased risk for the development of cardiovascular events.

Square wave voltammetric determination of the angiotensin-converting enzyme inhibitors cilazapril, quinapril and ramipril in pharmaceutical formulations

The angiotensin-converting enzyme inhibitors cilazapril, quinapril and ramipril are reduced at a hanging mercury drop electrode in the pH range 3.5-13 using Britton-Robinson buffers as supporting electrolyte and KCl as ionic medium. Square wave voltammetry has proved to be the most suitable electroanalytical technique for the quantitative voltammetric determination of these antihypertensive drugs. Optimisation of the chemical and instrumental variables was carried out. Analyses were performed in 0.02 M borate buffer at pH 9.5 and 0.5 M KCl as ionic medium, using a pulse amplitude of 50 mV and a frequency of 150 Hz. A linear relationship between peak current and concentration was found in the interval 0.5-8 microg/ml for cilazapril and up to 6 microg/ml for quinapril and ramipril, allowing the direct determination of their pharmaceutical formulations alone or mixed with hydrochlorothiazide. Good accuracy and repeatativity were obtained.

ACE inhibition versus angiotensin type 1 receptor antagonism: differential effects on PAI-1 over time

ACE inhibition reduces plasminogen activator inhibitor-1 (PAI-1), a risk factor for myocardial infarction, whereas the effect of angiotensin receptor antagonism on PAI-1 is uncertain. The present study compares the time course of effects of ACE inhibition and angiotensin type 1 (AT1) receptor antagonism on morning plasma PAI-1 antigen. Blood pressure and endocrine, metabolic, and fibrinolytic variables were measured in 20 insulin-resistant (defined by fasting glucose >8.3 mmol/L, body mass index >28 kg/m2, or fasting serum triglyceride > or =2.8 mmol/L) hypertensive subjects (mean age, 47.9+/-2.1 years) (1) before and after 1 week of hydrochlorothiazide 12.5 mg/d, and (2) before and 1, 3, 4, and 6 weeks after addition of ramipril (escalated to 10 mg/d) or losartan (escalated to 100 mg/d). Hydrochlorothiazide decreased systolic (P=0.011) and diastolic (P=0.019) pressure. Ramipril (from 133.6+/-5.1/94.5+/-2.4 to 127.0+/-3.1/91.4+/-3.3 mm Hg) or losartan (from 137.0+/-3.9/93.1+/-2.9 to 123.7+/-2.6/86.4+/-2.1 mm Hg) further reduced systolic (P=0.009) and diastolic (P=0.037) pressure. The pressure effects of the 2 drugs were similar. Hydrochlorothiazide increased plasma PAI-1 (P=0.013) but not tissue-type plasminogen activator (tPA) (P=0.431) antigen. Addition of either ramipril or losartan significantly decreased plasma PAI-1 antigen (P=0.046). However, the effect of losartan on PAI-1 antigen was not sustained throughout the 6-week treatment period, such that there was a significant drugxtime interaction (P=0.043). tPA antigen decreased during either ramipril or losartan (P=0.032), but tPA activity decreased only during losartan (P=0.018). Short-term interruption of the renin-angiotensin-aldosterone system by either ACE inhibition or AT1 receptor antagonism decreases PAI-1 antigen, but the duration of this effect is greater for ACE inhibition than for AT1 receptor antagonism.

Ramipril: a review of its use in the prevention of cardiovascular outcomes

Ramipril, an angiotensin-converting enzyme (ACE) inhibitor, is a prodrug which is rapidly hydrolysed after absorption to the active metabolite ramiprilat. Earlier trials have shown that ACE inhibitors, when given to patients with low ejection fractions, have reduced the relative risk of myocardial infarction (MI) and other ischaemic events by 14 to 23%. Subsequently, the double-blind, randomised, placebo-controlled, multicentre Heart Outcomes Prevention Evaluation (HOPE) study has shown that, in patients who are not known to have low ejection fraction or heart failure but are at increased risk for developing cardiovascular events, ramipril reduced the incidence of stroke, MI and death due to cardiovascular disease. Results from the HOPE study, in which 9297 patients were randomised to receive either ramipril 10 mg/day or placebo for a mean of 4.5 years, indicate that ramipril reduced the relative risk of the composite outcome of MI, stroke and cardiovascular death by 22%. The incidence of the composite outcome was significantly lower in the ramipril group than in the placebo group (14.0 vs 17.8%). Patients who received ramipril, compared with placebo recipients, had a significantly decreased incidence of stroke, MI or death due to cardiovascular disease (3.4 vs 4.9%, 9.9 vs 12.3% and 6.1 vs 8.1%, respectively). The relative risk of death from any cause was reduced among patients who received ramipril. In addition, treatment with ramipril reduced as the incidence of revascularisation procedures, and, among patients with diabetes mellitus, ramipril reduced the incidence of complications related to diabetes mellitus, including the development of overt nephropathy. Moreover, in patients without a previous diagnosis of diabetes mellitus, ramipril, compared with placebo, significantly reduced the development of diabetes mellitus. Furthermore, compared with patients receiving placebo, patients receiving ramipril had a reduced rate of progression of carotid artery wall thickness.

CONCLUSION

Ramipril 10 mg/day can significantly reduce the incidence of MI, stroke or death from cardiovascular causes in patients aged > or =55 years who are at increased risk for the development of ischaemic cardiovascular events due to a history of stroke, coronary artery disease (with controlled blood pressure), diabetes mellitus plus at least one other risk factor or peripheral vascular disease but no heart failure or low ejection fraction. Therefore, in addition to dietary and lifestyle modifications, ramipril should be an integral part of secondary prevention therapy in patients at increased risk for the development of cardiovascular events.

Moexipril. A review of its use in the management of essential hypertension

Moexipril is a prodrug which is hydrolysed after oral administration to its active metabolite moexiprilat, an inhibitor of the angiotensin converting enzyme (ACE). Once daily administration of moexipril 7.5 or 15 mg effectively reduces blood pressure in patients with essential hypertension (including the elderly and postmenopausal women with this condition). In double-blind randomised comparative studies, moexipril 7.5 to 15 mg once daily showed similar efficacy to other antihypertensive agents, including captopril, hydrochlorothiazide, atenolol, metoprolol, sustained release verapamil and nitrendipine. Combined therapy with hydrochlorothiazide and moexipril had a significantly greater antihypertensive effect than either agent alone. Moexipril is well tolerated by the majority of patients and compares well in this respect with other antihypertensive agents. Its tolerability profile appears to be characteristic of ACE inhibitors as a class (the most common adverse events being headache, symptoms of upper respiratory tract infection and cough). Moexipril generally had no clinically significant effect on lipid, glucose or electrolyte metabolism or haematological parameters, and, in particular, it was not associated with any significant changes in lipid or glucose metabolism in postmenopausal women (with or without hormone replacement therapy).

CONCLUSIONS

Once daily moexipril is a useful agent for the treatment of essential hypertension, which compares well with currently available options in terms of clinical efficacy and tolerability. In addition, clinical experience to date supports its use in postmenopausal women.

Use of angiotensin-converting enzyme inhibitors as monotherapy and in combination with diuretics and calcium channel blockers

Angiotensin-converting enzyme (ACE) inhibitors have earned an important place in medical therapy since their discovery about two decades ago. This family of drug has grown tremendously since the introduction of captopril in 1981. There are currently more than 14 ACE inhibitors in the world and 9 are available in the United States. Although these agents share many similarities, they differ in their pharmacokinetic properties, approved indications, and cost. This paper provides guidance for selection of ACE inhibitors by examining the pharmacokinetics, pharmacodynamics, drug interactions, adverse effects, and cost of these agents. Combination products of ACE inhibitors with either diuretics or calcium channel blockers also are reviewed.

Clinical pharmacokinetics of vasodilators. Part I

Understanding the mechanism of action and the pharmacokinetic properties of vasodilatory drugs facilitates optimal use in clinical practice. It should be kept in mind that a drug belongs to a class but is a distinct entity, sometimes derived from a prototype to achieve a specific effect. The most common pharmacokinetic drug improvement is the development of a drug with a half-life sufficiently long to allow an adequate once-daily dosage. Developing a controlled release preparation can increase the apparent half-life of a drug. Altering the molecular structure may also increase the half-life of a prototype drug. Another desirable improvement is increasing the specificity of a drug, which may result in fewer adverse effects, or more efficacy at the target site. This is especially important for vasodilatory drugs which may be administered over decades for the treatment of hypertension, which usually does not interfere with subjective well-being. Compliance is greatly increased with once-daily dosing. Vasodilatory agents cause relaxation by either a decrease in cytoplasmic calcium, an increase in nitric oxide (NO) or by inhibiting myosin light chain kinase. They are divided into 9 classes: calcium antagonists, potassium channel openers, ACE inhibitors, angiotensin-II receptor antagonists, alpha-adrenergic and imidazole receptor antagonists, beta 1-adrenergic agonist, phosphodiesterase inhibitors, eicosanoids and NO donors. Despite chemical differences, the pharmacokinetic properties of calcium antagonists are similar. Absorption from the gastrointestinal tract is high, with all substances undergoing considerable first-pass metabolism by the liver, resulting in low bioavailability and pronounced individual variation in pharmacokinetics. Renal impairment has little effect on pharmacokinetics since renal elimination of these agents is minimal. Except for the newer drugs of the dihydropyridine type, amlodipine, felodipine, isradipine, nilvadipine, nisoldipine and nitrendipine, the half-life of calcium antagonists is short. Maintaining an effective drug concentration for the remainder of these agents requires multiple daily dosing, in some cases even with controlled release formulations. However, a coat-core preparation of nifedipine has been developed to allow once-daily administration. Adverse effects are directly correlated to the potency of the individual calcium antagonists. Treatment with the potassium channel opener minoxidil is reserved for patients with moderately severe to severe hypertension which is refractory to other treatment. Diazoxide and hydralazine are chiefly used to treat severe hypertensive emergencies, primary pulmonary and malignant hypertension and in severe preeclampsia. ACE inhibitors prevent conversion of angiotensin-I to angiotensin-II and are most effective when renin production is increased. Since ACE is identical to kininase-II, which inactivates the potent endogenous vasodilator bradykinin, ACE inhibition causes a reduction in bradykinin degradation. ACE inhibitors exert cardioprotective and cardioreparative effects by preventing and reversing cardiac fibrosis and ventricular hypertrophy in animal models. The predominant elimination pathway of most ACE inhibitors is via renal excretion. Therefore, renal impairment is associated with reduced elimination and a dosage reduction of 25 to 50% is recommended in patients with moderate to severe renal impairment. Separating angiotensin-II inhibition from bradykinin potentiation has been the goal in developing angiotensin-II receptor antagonists. The incidence of adverse effects of such an agent, losartan, is comparable to that encountered with placebo treatment, and the troublesome cough associated with ACE inhibitors is absent.

An open-label, noncomparative, multicenter study of ramipril in the treatment of patients with mild-to-moderate hypertension

Ramipril, a once-a-day angiotensin-converting enzyme inhibitor, was studied in the treatment of mild-to-moderate hypertension in 240 patients. A total of 194 patients (111 women and 83 men; mean +/- SD age, 46.0 +/- 11.5 years) were considered assessable for study. After a 2-week placebo washout phase, all patients received ramipril 2.5 mg once daily for 4 weeks. At 4 weeks, blood pressure was evaluated for response to therapy. Responders to 2.5 mg were continued on the same dose; nonresponders received 5 mg once daily for another 4 weeks. Results showed that 91% of patients responded after 8 weeks of therapy, 60% to 2.5 mg and 31% to 5 mg. Ramipril was well tolerated and, because of its long half-life, can be considered a true once-a-day angiotensin-converting enzyme inhibitor for the treatment of patients with mild-to-moderate hypertension.

Meta-analysis of morbidity and mortality in five exercise capacity trials evaluating ramipril in chronic congestive cardiac failure

In 5 separate exercise capacity trials in similar patients with chronic congestive heart failure performed in Europe, the United States, and South Africa, 627 patients were randomized to ramipril and 428 to placebo. The dose of ramipril ranged from 1.25 to 20 mg/day. Follow-up was at 12 or 24 weeks. None of the trials were designed to assess efficacy with regard to clinical outcome. To assess in the combined experience whether there was an effect of ramipril on mortality, hospitalization, functional classification (New York Heart Association class), and exercise capacity, we pooled data from each trial and performed a mata-analysis. Of the patients randomized to ramipril and placebo, respectively, and based on intention to treat, 14 (2.2%) and 18 (3.8%) patients died (odds ratio 0.60, 95% confidence interval 0.28 to 1.29), and 59 (9.4%) and 67 (14.3%) patients died or were hospitalized (odds ratio 0.68, 95% confidence interval 0.46 to 1.00). The New York Heart Association class improved in 29% and 25% respectively, whereas 8% and 15% deteriorated (p=0.04, based on intention to treat; death and hospitalization considered as deterioration). In ranked comparisons based on intention to treat and with imputation of exercise time as 0 for patients who were unable to exercise because of death or who were hospitalized, exercise capacity was significantly improved by rampril. We concluded that rampiril is likely to have an effect on mortality, morbidity, and functional capacity in patients with chronic congestive heart failure similar to that of other angiotensin-converting enzyme inhibitors.

Ramipril decreases chlorthalidone-induced loss of magnesium and potassium in hypertensive patients

A double-blind clinical trial was conducted to compare the efficacy of and electrolyte changes caused by ramipril-chlorthalidone combination treatment (5 mg + 25 mg) and chlorthalidone monotherapy (25 mg daily) in patients with hypertension. After a 4-week placebo period, 32 patients (mean age, 51 +/- 9 years) with essential hypertension (average blood pressure of 181.4/104.5 +/- 13.0/6.9 mmHg) were randomly assigned to receive combination therapy (group A, n = 17) or monotherapy (group B, n = 15). After 12 weeks of active treatment, systolic and diastolic blood pressure decreased by 16.1% and 13%, respectively, for patients taking combined therapy, and by 12.7% and 9.8%, respectively, for patients taking monotherapy. The difference was significant for between-group comparisons. There were no changes in serum sodium concentration, but a significant similar increase in 24-hour urinary sodium excretion was seen in both groups. Serum calcium levels increased slightly and 24-hour urinary calcium excretion decreased significantly in both groups, probably due to chlorthalidone administration. Serum potassium levels increased slightly in group A (from 4.16 +/- 0.39 mmol/L to 4.30 +/- 0.42 mmol/L) and decreased slightly in group B (from 4.18 +/- 0.32 mmol/L to 3.99 +/- 0.49 mmol/L). Urinary potassium excretion did not change significantly in group A, but increased by approximately 15% in group B. There was a decrease in 24-hour urinary magnesium excretion (from 4.01 +/- 1.24 mmol/24 hours to 3.50 +/- 0.93 mmol/24 hours) in group A and an increase (from 3.49 +/- 0.98 mmol/24 hours to 4.35 +/- 1.12 mmol/24 hours) in group B. At the end of the trial these changes were significant in between-group comparisons. Consistent with the previously shown amelioration by ramipril of thiazide-induced metabolic side-effects, ramipril appears to improve magnesium balance during cotreatment with chlorthalidone.

ACE inhibitors. Differential use in elderly patients with hypertension

High blood pressure (BP) in the elderly must not be ignored as a normal consequence of aging. The criteria for the diagnosis of hypertension and the necessity to treat it are the same in elderly and younger patients. The aim of treatment of elderly hypertensive patients is to decrease BP safely and to reduce risk factors associated with cerebrovascular, cardiovascular and renal morbidity and mortality. The treatment of elderly hypertensive patients should be adjusted according to the needs of the individual, based upon age, race, severity of hypertension, co-existing medical problems, other cardiovascular risk factors, target-organ damage, risk-benefit considerations and costs. In addition to the elevated BP, other cardiovascular risk factors include smoking, glucose intolerance, hyperinsulinaemia, dyslipidaemia, hypercreatininaemia, peripheral vascular disease, left ventricular hypertrophy, and microalbuminuria (or albuminuria). Thus, the choice of initial antihypertensive therapy in elderly hypertensive patients should be based not only on the expected response, but also on the effects of therapy on lipid, potassium, glucose and uric acid levels, and left ventricular anatomy and function. Co-existing medical conditions (such as asthma, diabetes mellitus, heart failure, renal failure, gout, coronary artery disease, hyperlipidaemia and peripheral vascular disease) are major determinants for the selection of antihypertensive medications. With previous therapies (diuretics, beta-blockers, etc.), good BP control in the elderly was associated with clear and statistically significant reductions in stroke-related morbidity and mortality, but the overall effects on cardiovascular and renal complications of hypertension was either more variable or less obvious. Angiotensin converting enzyme (ACE) inhibitors are not only efficacious antihypertensive agents in the elderly, but also appear promising in counteracting some of the cardiovascular and renal consequences of hypertension. They are well tolerated and have a relatively low incidence of adverse effects. ACE inhibitors possess ancillary characteristics that are potentially beneficial for many elderly patients, including reduction of left ventricular mass, lack of metabolic and lipid disturbances, no adverse CNS effects, no risk of induction of heart failure, and a low risk of orthostatic hypotension. Since ACE inhibitors may improve perfusion to the heart, kidney and brain, they are well worth considering for the treatment of elderly patients with hypertensive target organ damage, especially in patients with heart failure, and diabetic patients with early nephropathy.

Tonic stimulation of renin gene expression by nitric oxide is counteracted by tonic inhibition through angiotensin II

This study was designed to examine the possible involvement of prostaglandins and nitric oxide (NO) in the renin stimulatory effect of angiotensin II (AngII) antagonists. To this end, plasma renin activities (PRAs) and renal renin mRNA levels were assayed in rats that were treated with the Ang-converting enzyme inhibitor ramipril or with the AngII AT1-receptor antagonist losartan. Ramipril and losartan increased PRA values from 7.5 +/- 1.6 to 86 +/- 6 and 78 +/- 22 ng of AngI per h per ml and renin mRNA levels from 112 +/- 9% to 391 +/- 20% and 317 +/- 10%, respectively. Inhibition of prostaglandin formation with indomethacin did not influence basal or ramipril-affected PRA. Basal renin mRNA levels also were unchanged by indomethacin, while increases in renin mRNA levels after ramipril treatment were slightly reduced by indomethacin. Inhibition of NO synthase by nitro-L-arginine methyl ester (L-NAME) reduced PRA values to 3.2 +/- 0.9, 34 +/- 13, and 12.1 +/- 2.7 ng of AngI per h per ml in control, ramipril-treated, and losartan-treated animals, respectively. Renin mRNA levels were reduced to 77 +/- 14% under basal conditions and ramipril- and losartan-induced increases in renin mRNA levels were completely blunted after addition of L-NAME. The AngII antagonists, furthermore, induced an upstream recruitment of renin-expressing cells in the renal afferent arterioles, which was also blunted by L-NAME. These findings suggest that renin mRNA levels are tonically increased by NO and that the action of NO is counteracted by AngII.

ACE inhibitors. Drug interactions of clinical significance

ACE inhibitors are used widely in the treatment of hypertension and congestive heart failure, but there is only limited information on adverse interactions between ACE inhibitors and other cardiovascular or noncardiovascular drugs. The present article provides an overview of this issue, with emphasis on those interactions having the greatest clinical implications. In patients who have been sodium and/or volume depleted by thiazide or loop diuretics, the additional use of ACE inhibitors can lead to an excessive reduction in blood pressure and symptomatic hypotension. An increase in serum potassium levels may occur after coadministration of potassium-sparing diuretics and ACE inhibitors, resulting in hyperkalaemia especially in patients with renal insufficiency. The incidence of acute renal failure may be associated with ACE inhibitor therapy when these drugs are combined with nonsteroidal anti-inflammatory agents and given to patients whose renal function becomes increasingly dependent on angiotensin II and prostaglandins. There is some evidence, albeit scant, linking ACE inhibitors with the induction of lithium toxicity in patients maintained on lithium, and with the occurrence of severe hypersensitivity reactions in patients undergoing haemodialysis, venom immunisation or concomitant allopurinol therapy.

Ramipril and experimental vein graft intimal hyperplasia

Angiotensin-converting enzyme (ACE) inhibitors have been shown to reduce the intimal proliferation in animal models of arterial angioplasty and vein bypass grafting. This study examines the effect of high-dose ramipril, an ACE inhibitor that does not contain a sulfhydryl group, on the development of intimal hyperplasia in experimental vein bypass grafts. Twenty New Zealand White rabbits underwent common carotid interposition bypass grafting. Twelve were treated with ramipril (2 mg/kg/day; po) five days prior to surgery and thereafter until harvest. The remaining 8 animals were used as controls. Vein grafts were harvested at twenty-eight days by pressure fixation (80 mmHg). The grafts were sectioned into proximal, middle, and distal thirds, and the thickness of the intima and the media and the area of the lumen from each segment were determined by videomorphometry. The effect of ramipril on the [H3]thymidine incorporation into DNA of serum-stimulated smooth muscle cells (culture passage 6 to 12) was also assessed. There was a 50% mortality rate in the rabbits that received ramipril, and this was assumed to be related to the high dose of the drug. Ramipril treatment reduced mean vein graft intimal area by 34% (P > 0.05), but this was accompanied by an increase of 73% in the mean medial area of the vein grafts as compared with controls. These changes resulted in a decrease in the mean intimal ratio (intima/[intima + media]) by 39% in the ramipril group as compared with controls. Ramipril did not inhibit [H3]thymidine incorporation into DNA of serum-stimulated smooth muscle cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of angiotensin converting enzyme inhibition on relation of atrial natriuretic peptide concentration to atrial pressure in heart failure

OBJECTIVE

To examine the relation between haemodynamics and atrial natriuretic peptide concentration during short term angiotensin converting enzyme inhibition.

DESIGN

Patients were randomly allocated to receive placebo or one of three doses of the angiotensin converting enzyme inhibitor ramipril.

SETTING

Cardiac units of two tertiary referral hospitals.

SUBJECTS

38 Patients with stable congestive heart failure caused by ischaemic heart disease.

METHODS

Data were collected over a 24 hour period and assessed with the aim of distinguishing between the haemodynamic effects on plasma concentrations of atrial natriuretic peptide and the direct effects of the study drug, vasopressin concentrations, and angiotensin converting enzyme activity.

RESULTS

Pulmonary capillary wedge pressure was the main predictor of the plasma concentration of atrial natriuretic peptide. A higher plasma concentration of this peptide with a given pulmonary capillary wedge pressure was found after 24 hours of treatment with 2.5 mg and 5 mg of ramipril. Plasma concentration of the active metabolite, change in arginine vasopressin concentration or degree of angiotensin converting enzyme inhibition did not significantly predict change in plasma concentration of atrial natriuretic peptide or in the ratio of atrial natriuretic peptide concentration to pulmonary capillary wedge pressure.

CONCLUSIONS

A gradual increase in plasma concentration of atrial natriuretic peptide with a given pulmonary capillary wedge pressure, occurs during short term high degree inhibition of angiotensin converting enzyme. The causative mechanisms are yet to be identified. Such a change in the relation between central haemodynamics and atrial natriuretic peptide concentration may contribute to the beneficial effects of angiotensin converting enzyme inhibition in patients with congestive heart failure due to ischaemic heart disease.

Clinical pharmacokinetics of ramipril

Ramipril is a long-acting nonsulfhydryl angiotensin converting enzyme (ACE) inhibitor introduced for clinical use about a decade ago. Ramipril is a prodrug that undergoes de-esterification in the liver to form ramiprilat, its active metabolite. Ramipril rapidly distributes to all tissues, with the liver, kidneys and lungs showing markedly higher concentrations of the drug than the blood. After absorption from the gastrointestinal tract, rapid hydrolysis of ramipril occurs in the liver. In the therapeutic concentration range, protein binding of ramipril and ramiprilat is 73 and 56%, respectively. Ramiprilat binds to ACE with high affinity at concentrations similar to that of the enzyme and establishes equilibrium slowly. Although ramipril is metabolised by hepatic and renal mechanisms to both a glucuronate conjugate and a diketopiperazine derivative, most of the drug is excreted in the urine as ramiprilat and the glucuronate conjugate of ramiprilat. Elimination from the body is characterised by a relatively rapid initial phase with a half-life of 7 hours and a late phase with a half-life of about 120 hours. No clinically significant pharmacokinetic interactions between ramipril and other drugs have been reported. The drug has been generally well tolerated with the most prevalent adverse effects being dizziness (3.4%), headache (3.2%), weakness (1.9%) and nausea (1.7%). Ramipril is an effective and well tolerated drug for the treatment of hypertension and congestive heart failure in all patients, including those with renal or hepatic dysfunction, and the elderly.

New avenues in antihypertensive drug treatment

After a brief synopsis of the classical antihypertensive drugs a survey is given of the newer therapeutics, such as calcium antagonists, ACE-inhibitors and alpha 1-adrenoceptor antagonists. Experimental drugs, such as imidazoline receptor agonists, renin inhibitors, angiotensin II receptor antagonists, alpha 2-adrenoceptor antagonists, potassium channel openers, ketanserin, endopeptidase inhibitors, and hybrid (multifactorial) drugs are discussed, with special attention for their modes of action. In spite of the ever increasing number of antihypertensive drugs and principles, the large scale of clinical evidence for a beneficial effect of long-term treatment (in particular with respect to protection against stroke) remains limited to diuretics and beta-blockers. In spite of this limitation it seems worthwhile to consider the newer antihypertensive drugs as well, especially for optimal treatment of the individual patient. The newer drugs may in particular offer special advantages in the presence of concomitant diseases, such as diabetes mellitus, hyperlipidaemia, angina pectoris or congestive heart failure.

Effect of ramipril on alpha-adrenoceptor-mediated oscillatory contractions in tail artery of hypertensive rats

Recent studies indicate that norepinephrine-induced contractile oscillations in the tail artery from stroke-prone spontaneously hypertensive rats (SHRSP) may be a vascular phenomenon independent of blood pressure level. The objectives of this study were: (1) to characterize pharmacologically the alpha-adrenoceptor mediating norepinephrine-induced oscillations in tail artery; and (2) to investigate the relationship between blood pressure level, altered by treatments with hydralazine/hydrochlorothiazide or the angiotensin converting enzyme inhibitor ramipril, and the observation of norepinephrine-induced oscillations in tail artery. The alpha 2-adrenoceptor agonists clonidine and guanabenz potently stimulated oscillatory contractions in the tail artery while the alpha 1-adrenoceptor agonists phenylephrine and methoxamine were considerably less potent. Yohimbine, an alpha 2-adrenoceptor antagonist, but not the alpha 1-adrenoceptor antagonist prazosin demonstrated high affinity for the receptor mediating norepinephrine-induced oscillatory contractions. These results support the hypothesis that norepinephrine-induced oscillatory contractions in the tail artery from SHRSP occur primarily through stimulation of alpha 2-adrenoceptors. Ramipril lowered blood pressure in SHRSP after 4 weeks of treatment during 6-10 weeks of life but did not alter the ability of the alpha 2-adrenoceptor agonist clonidine (10(-5) M) to induce contractile oscillations in tail arteries from SHRSP, indicating these oscillations are not a secondary effect of high blood pressure. These studies suggest that norepinephrine-induced oscillations in tail artery from SHRSP may be a vascular trait separate and distinct from blood pressure level and angiotensin II expression early in life.

Dose-response differences in the ability of ramipril to improve retention in diabetic mice

Ramipril blocks the conversion of angiotensin I to II. The literature indicates that diabetes is often associated with mild impairment of learning and memory. The study reports the effects of ramipril on memory retention in diabetic and non-diabetic mice. Mice were made diabetic by an injection of streptozocin. After overt signs of diabetes were present, diabetic or vehicle-treated mice were partially trained on a footshock active avoidance task. Immediately after training, ramipril (0.5-1.5 mg/kg s.c.) was administered and retention was tested by continuing training one week later until mice avoided footshock on five out of six trails. The results indicate that ramipril enhanced retention of both diabetic and control mice but it required about 5 times as much ramipril in diabetic as control mice to achieve the same effect on retention. Increased sensitivity to angiotensin II may play a role in cognitive impairment in diabetes.

Ramipril prevents impaired endothelium-dependent relaxation in arteries from rabbits fed an atherogenic diet

Endothelium-dependent relaxation in arteries is attenuated in clinical and experimental atherosclerosis. This study investigates the endothelial preservation properties of the angiotensin converting enzyme inhibitor, ramipril, by assessing its ability to restore endothelium-dependent responsiveness in blood vessels from rabbits fed an atherogenic diet (0.25% cholesterol; 3% coconut oil; 12 weeks). Seven rabbits fed the atherogenic diet received ramipril (3 mg/kg mixed into their food daily) and 6 rabbits were maintained on the atherogenic diet alone. Control rabbits (n = 6) were fed a standard diet and did not receive ramipril. At the end of the dietary intervention, the rabbits were killed and blood was collected for measurement of the lipid profile. The thoracic aorta was isolated and half was frozen for pathologic review while the other half was cut into rings and placed in a muscle bath for measurement of isometric force development. Dose response curves to phenylephrine (10(-9) to 10(-5) M) and angiotensin II (10(-10) to 3 x 10(-7) M) were completed. There was a minimal decrease in responsiveness to phenylephrine in vessels from rabbits eating the atherogenic diet compared with controls and no significant differences in the response to angiotensin II for any of the vessels. Following contraction by phenylephrine, acetylcholine (10(-9) to 10(-5) M) and nitroglycerin (10(-10) to 10(-5) M) dose response curves were completed. Relaxation to acetylcholine in aortic rings from control rabbits was observed, although in arteries from atherogenic rabbits relaxation was attenuated. This effect was prevented in the atherogenic rabbits fed ramipril. Responsiveness to the endothelium-independent vasodilator, nitroglycerin, was similar in arteries from the three rabbit groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical pharmacokinetics of angiotensin converting enzyme (ACE) inhibitors in renal failure

Arterial hypertension occurs frequently in patients with chronic renal failure. Antihypertensive treatment of arterial hypertension with angiotensin converting enzyme (ACE) inhibitors has been shown to be effective with a low incidence of adverse effects compared with other drug classes. Furthermore, treatment with ACE inhibitors may slow the progression of renal function impairment in certain groups of patients, such as those with diabetes. Most ACE inhibitors are prodrugs which are converted by hepatic esterolysis to an active diacid metabolite. Only captopril and lisinopril have sufficient oral bioavailability and are given as active drugs. ACE inhibitors can be subdivided into 3 classes with regard to the active group: the majority of ACE inhibitors are carboxyl-containing drugs, a new class of ACE inhibitors possess a phosphoryl-group and captopril and related compounds are sulfhydryl-containing drugs. The predominant elimination pathway of ACE inhibitors is excretion via the kidneys. Therefore, renal insufficiency is associated with reduced elimination of most ACE inhibitors and, thus, altered pharmacokinetic properties. This is most evident in chronic renal failure when glomerular filtration rates (GFR) are < 30 to 40 ml/min (1.8 to 2.4 L/h). As renal clearance decreases, the peak plasma concentration and area under the plasma concentration-time curve of the active drugs or diacids are increased and time to peak concentrations and half-life are prolonged. However, there are large between-drug differences in the changes in pharmacokinetic parameters, resulting in different degrees of drug accumulation after consecutive administration. This leads, for example, to high accumulation rates for drugs such as lisinopril, or cilazaprilat. In contrast, fosinopril, which is also excreted to a large extent by the hepatobiliary pathway, does not seem to accumulate in renal failure. In general, pharmacokinetics and conversion of prodrugs seem to be slightly affected in chronic renal failure; however, these changes do not appear to be clinically relevant. Efficiency of clearance for prodrugs or active drugs and their respective metabolites by haemodialysis or peritoneal dialysis varies considerably. For some ACE inhibitors, such as captopril or enalapril, the high elimination fraction by haemodialysis necessitates a supplemental dose after dialysis. Other ACE inhibitors, such as quinapril or cilazapril, are only poorly eliminated by haemodialysis or peritoneal dialysis. Dosage recommendations for treatment with ACE inhibitors in chronic renal failure depend on the specific pharmacokinetic properties of the various agents. For most ACE inhibitors, dosage adjustment is recommended in moderate and severe impairment of renal function, with resultant dosages being 25 to 50% of those recommended for patients with normal renal function.

Combination of ramipril and hydrochlorothiazide in the treatment of mild to moderate hypertension--Part 2: An open long-term study of efficacy and safety

In an open, multicenter extension of a short-term study, 159 patients with mild to moderate hypertension were treated with either ramipril monotherapy or a combination of ramipril and hydrochlorothiazide for up to 1 year. Patients started with either 5 mg ramipril once daily (responders in the short-term study) or a combination of ramipril 5 mg plus hydrochlorothiazide 25 mg once daily. The dose could be adjusted and nonresponders to ramipril monotherapy could have hydrochlorothiazide added. In the 38 patients treated with ramipril monotherapy, the largest drop in mean blood pressure (BP) had already occurred in the previous short-term study; from Week 2 in the long-term study, the BP remained stable with means below 150/90 mmHg. In the 83 patients treated with the combination for 50 weeks or more, mean BP continued to decrease until around Week 10 in the long-term study while therapy was being adjusted. Thereafter, it also remained stable with means below 150/85 mmHg. Both treatment groups showed good mean reductions at end point, as did the group of 38 patients treated with the combination for less than 50 weeks. High response rates (84-95%) were seen in all groups at end point. The combination was well tolerated and the efficacy of ramipril in combination with hydrochlorothiazide was maintained over the 1-year period of investigation.

Combination of ramipril and hydrochlorothiazide in the treatment of mild to moderate hypertension: Part 1--A double-blind, comparative, multicenter study in nonresponders to ramipril monotherapy

In a parallel-group multicenter study, the efficacy and safety of combination therapy with ramipril 5 mg plus hydrochlorothiazide 25 mg were compared double-blind with those of 5 mg and 10 mg ramipril monotherapy in patients with mild to moderate hypertension who had not responded adequately to ramipril 5 mg alone. Patients were initially treated single-blind for 1 week with ramipril 2.5 mg and 3 weeks with ramipril 5 mg. Of 240 patients enrolled, 165 were subsequently classed as nonresponders (diastolic blood pressure > 90 mmHg) and were randomized to one of the three double-blind treatments for a further 4 weeks. In the double-blind phase, the mean reductions in supine systolic and diastolic blood pressures at end point were significantly greater in the 5 mg plus 25 mg combination group (11.6/10.6 mmHg) than in the groups receiving ramipril 5 mg (6.2/5.9 mmHg; both p < 0.01) and ramipril 10 mg (7.4/7.1 mmHg; both p < 0.05). The proportion of responders at end point was also higher for combination therapy (72%) than for monotherapy (48% for ramipril 5 mg and 62% for ramipril 10 mg). All three treatments were well tolerated. Analysis of laboratory values revealed no clinically important changes.

Trandolapril in hypertension: overview of a new angiotensin-converting enzyme inhibitor

Trandolapril is a new angiotensin-converting enzyme (ACE) inhibitor that has been extensively investigated in vitro, in animals, in normal volunteers, and in hypertensive patients. It has been shown to exert all the effects typical for the class of ACE inhibitors, and has a marked impact on the reversal of structural hypertrophy of the myocardium and the arterial wall. Trandolapril is a prodrug that must be hydrolyzed to its active metabolite, trandolaprilat. This latter compound exhibits a particularly high affinity for converting enzyme, which results in a slow dissociation and one of the longest durations of action of any converting enzyme inhibitor known so far. Trandolapril reduces blood pressure consistently throughout the 24-hour period following intake. Accordingly, trandolapril, more than any other drug of its class, can be considered a true, once-a-day antihypertensive drug.

Effects of ACE inhibition supplementary to beta blockers and diuretics in early diabetic nephropathy

Angiotensin converting enzyme (ACE) inhibition has shown promising results in diabetic nephropathy, but long-term results on survival are not available. In a cohort of patients receiving antihypertensive treatment predominantly consisting of beta blockers in combination with diuretics, support for an improved survival has been presented. Addition of ACE inhibition to such a combination treatment may be favorable both due to the suggested renoprotective effects of ACE inhibitors and because diuretics activate the renin-angiotensin system. In 10 insulin-dependent diabetic patients with early diabetic nephropathy [urinary albumin excretion rate (UAE) less than 100o micrograms/min], who were receiving continuous therapy with metoprolol and bendroflumethiazide, a double-blind crossover study with four months addition of ramipril 5 mg (Ramace) and placebo was conducted. UAE (radioimmunoassay) and fractional albumin excretion were significantly reduced after the four months of ramipril administration [UAE: 114.1 x/divided by 1.3 (geometric mean x/divided by confidence factor] versus 174.6 x/divided by 1.2 micrograms/min, 2P less than 0.005). Renal plasma flow (clearance of 131I-hippuran) tended to increase [497 +/- 25 (mean +/- SE) vs. 464 +/- 28 ml/min/1.73 m2, 2P = 0.08], while GFR (125I-iothalamate) stayed unchanged (121 +/- 8 vs. 120 +/- 9 ml/min/1.73 m2). Mean arterial pressure during clearance studies fell moderately (95 +/- 3 vs. 101 +/- 1 mm Hg, 2P less than 0.05) and renal resistance was decreased (2P less than 0.03). ACE activity was suppressed in all patients. Twenty-four-hour ambulatory blood pressure measurements were not significantly different after the two periods (daytime averages: 91 +/- 2 vs. 93 +/- 2, nighttime 80 +/- 2 vs. 84 +/- 3 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Enalapril. A reappraisal of its pharmacology and therapeutic use in hypertension

Enalapril, an angiotensin converting enzyme (ACE) inhibitor usually administered orally once daily, decreases blood pressure by lowering peripheral vascular resistance without increasing heart rate or output. It is effective in lowering blood pressure in all grades of essential and renovascular hypertension. Patients not responding adequately to enalapril monotherapy usually respond with the addition of a thiazide diuretic (or a calcium antagonist or beta-blocker), and rarely require a third antihypertensive agent. Enalapril is at least as effective as other established and newer ACE inhibitors, and members of other antihypertensive drug classes including diuretics, beta-blockers, calcium antagonists and alpha-blockers, but therapy with enalapril may be less frequently limited by serious adverse effects or treatment contraindications than with other drug classes. The most frequent adverse effect limiting all ACE inhibitor therapy in clinical practice is cough. This favourable profile of efficacy and tolerability, and the substantial weight of clinical experience, explain the increasing acceptance of enalapril as a major antihypertensive treatment and supports its use as logical first-line therapeutic option.

The clinical pharmacology of angiotensin converting enzyme inhibitors in chronic heart failure

ACE inhibitors (ACEIs) have now been shown to improve symptoms and survival in patients with mild, moderate and severe chronic heart failure. Their mechanism of action is thought to be a combination of RAAS suppression and augmentation of bradykinin and prostaglandins. Although ACE inhibitors improve hemodynamics post myocardial infarction, we do not yet have consistent data on their effects on symptoms or survival in these particular patients. One other potential benefit is their effects on reperfusion injury and free radicals. As yet only minor differences have been found to exist between different ACEIs but increasing attention is now being focussed in this direction.

Perindopril. A review of its pharmacological properties and therapeutic use in cardiovascular disorders

Perindopril is a long acting angiotensin converting enzyme (ACE) inhibitor, which displays similar pharmacodynamic properties to other agents in this class. In common with enalapril, it is also a prodrug. After absorption, perindopril is hydrolysed to the active metabolite, perindoprilat, and with once daily administration adequate 24-hour inhibition of ACE is obtained. Perindopril 4 to 8mg once daily is usually effective for blood pressure control in patients with mild to moderate essential hypertension. Those patients who do not respond adequately to monotherapy with perindopril usually respond with the addition of a second agent, such as a thiazide diuretic. General practice trials indicate that perindopril is at least as effective and as well tolerated as usual therapeutic dosages of captopril, atenolol or hydrochlorothiazide plus amiloride in mild to moderate essential hypertension. Preliminary results indicate that perindopril may also be effective in patients with severe hypertension or congestive heart failure. Perindopril is generally well tolerated and has an adverse effect profile similar to that of other ACE inhibitors. It further clinical experience confirms initial findings, perindopril is likely to represent a useful alternative to other members of the ACE inhibitor class in all grades of hypertension and congestive heart failure.

Cilazapril. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in cardiovascular disease

Cilazapril is an orally active angiotensin converting enzyme (ACE) inhibitor which lowers peripheral vascular resistance without affecting heart rate. Like enalapril and ramipril it is a prodrug, and is hydrolysed after absorption to cilazaprilat, which has a long terminal phase elimination half-life permitting once daily administration. Given once daily at doses between 2.5 and 5 mg, cilazapril reduces arterial blood pressure in patients with mild to moderate essential and renal hypertension. Patients who do not respond adequately to cilazapril monotherapy usually respond with the addition of a diuretic such as hydrochlorothiazide. Preliminary data suggest that cilazapril is of comparable antihypertensive efficacy to usual therapeutic dosages of hydrochlorothiazide, slow release propranolol, nitrendipine, captopril and enalapril. In small studies cilazapril has produced sustained beneficial haemodynamic effects in patients with congestive heart failure. Cilazapril has been well tolerated and exhibits tolerability typical of ACE inhibitors as a class, including their lack of detrimental effect on glucose or lipid metabolism. Cilazapril should provide an effective alternative in the treatment of hypertension and, if preliminary data are confirmed, in congestive heart failure.

Newer ACE inhibitors. A look at the future

Available information indicates that about 78 new molecules belonging to the class of angiotensin converting enzyme (ACE) inhibitors are under investigation, and that at least 11 or 12 of the newer ACE inhibitors will be available for clinical use. The newer ACE inhibitors can be classified, according to the zinc ion ligand of ACE, into 3 main chemical classes: sulfhydryl-, carboxyl- and phosphoryl-containing ACE inhibitors. All the newer sulfhydryl-containing ACE inhibitors differ from captopril since they are prodrugs, and among them alacepril and probably moveltipril (altiopril, MC 838) are converted in vivo to captopril. When compared with captopril, they show a slower onset and a longer duration of action, and obviously the same route of elimination. Zofenopril, a prodrug that is converted in vivo to the active diacid, shows a greater potency, a similar peak time and a longer duration of action than captopril and, unlike captopril, partial elimination through the liver. The newer carboxyl-containing ACE inhibitors are prodrugs which are converted in vivo to active diacids. Like enalaprilat, they are excreted via the kidney; the exception is spirapril, which is totally eliminated by the liver. Compared to enalapril, benazepril shows an earlier peak time and a slightly shorter terminal half-life, cilazapril and ramipril have an earlier peak time and even longer terminal half-life, perindopril shows similar peak time and terminal half-life, while delapril, quinapril and spirapril show an earlier peak time and a shorter half-life. The phosphoryl-containing ACE inhibitors belong to a new chemical class. Fosinopril is a prodrug which is converted to the active diacid in vivo, shows a relatively late peak time, a long terminal half-life, and is eliminated partially by the liver. SQ 29852, the only newly developed ACE inhibitor which is not a prodrug, seems to be more effective than captopril, with a much longer lasting effect and elimination through the kidney. When the differences in potency between these drugs are compensated by dosage adjustment, all the newer ACE inhibitors are expected to exert a similar amount of inhibition of circulating ACE, and therefore to inhibit to a similar extent the generation of circulating angiotensin II and the breakdown of bradykinin. Obviously they may differ in timing and the duration of circulating ACE inhibition according to their pharmacokinetic properties. With regard to the possibility that they may stimulate prostaglandin synthesis, it is suggested that this action, which does not seem to be specific to this drug class, plays only a minor role in their antihypertensive action; the hypothesis that the sulfhydryl group exerts an additional stimulating action remains to be proved.(ABSTRACT TRUNCATED AT 400 WORDS)