Calcium channel blockers in acute myocardial infarction and unstable angina: an overview

Negative findings but positive contributions in cardiovascular research

Researchers have always concluded that results that do not support the hypothesis as unimportant, unworthy, or simply not good enough for publication. However, negative findings are essential for the progress of science and its self-correcting nature. We also believe in the importance and indispensability of negative results. Therefore, in this review, we discussed the factors contributing to the publication bias of negative results and the problems to assess the factuality and validity of negative results. Moreover, we emphasized the importance of reporting negative results in cardiovascular research, including treatments, and suggest that the negative results could clarify previously controversial topics in the treatment of cardiovascular diseases and prompt the translation of research on precision cardiovascular disease prevention and treatment.

Impact of Calcium Channel Blockers on Aspirin Reactivity in Patients with Coronary Artery Disease

PURPOSE

Calcium channel blockers (CCBs) do not reduce the risk of initial or recurrent myocardial infarction (MI) in patients diagnosed with stable coronary artery disease (CAD). The aim of this current study was to evaluate the association between CCBs and aspirin resistance in patients with CAD.

METHODS

Patients with stable CAD who were regularly taking aspirin (75-100 mg qd) for at least 1 month prior to enrollment in the study were included. The VerifyNow system was used for platelet function testing with high on-aspirin platelet reactivity (HAPR) defined as aspirin reaction units (ARU) >550. We compared patients treated with CCBs versus control group.

RESULTS

Five hundred three patients with CAD were included in this study, and 88 were treated with CCBs. Mean age (67.9±9.7 in the CCB group vs. 66.5±11.4 in the control group), gender (77.3 male vs. 82.9%), rates of diabetes mellitus (34.7 vs. 36.9%), rates of CKD (23.5 vs. 23.5%), dyslipidemia (85.1 vs. 85.3%), and statin therapy (89.5 vs. 90.7%) were similar. The mean ARU was 465.4±70.0 for patients treated with CCBs versus 445.2±60.0 in controls (p=0.006). Similarly, 15.9% of CCB patients demonstrated HAPR compared to 7.0% (p=0.006). The administration of CCBs was independently associated with HAPR in a multivariate analysis (OR 1.72, 95% CI: 1.04-8.91, p=0.047) as well as in propensity score matched analysis (OR 1.56; CI: 1.22-1.93; p<0.001).

CONCLUSIONS

Usage of CCBs is positively correlated with aspirin resistance. These findings may suggest an adverse pharmacologic effect of CCBs among patients with stable CAD treated with aspirin.

Long-acting tunable release of amlodipine loaded PEG-PCL micelles for tailored treatment of chronic hypertension

Hypertension is a chronic condition that requires lifelong therapeutic management. Strict adherence to drug administration timing improves efficacy, while poor adherence leads to safety concerns. In light of these challenges, we present a nanofluidic technology that enables long-acting drug delivery with tunable timing of drug administration using buried gate electrodes in nanochannels. We developed a poly(ethylene glycol) methyl ether-block-poly(ε-caprolactone) (PEG-PCL)-based micellar formulation of amlodipine besylate, a calcium channel blocker for hypertension treatment. The electrostatically charged PEG-PCL micellar formulation enhanced drug solubility and rendered amlodipine responsive to electrostatic release gating in nanochannels for sustained release at clinically relevant therapeutic dose. Using a low-power (<3 VDC) gating potential, we demonstrated tunable release of amlodipine-loaded micelles. Additionally, we showed that the released drug maintained biological activity via calcium ion blockade in vitro. This study represents a proof of concept for the potential applicability of our strategy for chronotherapeutic management of hypertension.

Calcium Channel Blockers in Acute Care: The Links and Missing Links Between Hemodynamic Effects and Outcome Evidence

Calcium channel blockers (CCBs) exert profound hemodynamic effects via blockage of calcium flux through voltage-gated calcium channels. CCBs are widely used in acute care to treat concerning, debilitating, or life-threatening hemodynamic changes in many patients. The overall literature suggests that, for systemic hemodynamics, although CCBs decrease blood pressure, they normally increase cardiac output; for regional hemodynamics, although they impair pressure autoregulation, they normally increase organ blood flow and tissue oxygenation. In acute care, CCBs exert therapeutic efficacy or improve outcomes in patients with aneurysmal subarachnoid hemorrhage, acute myocardial infarction and unstable angina, hypertensive crisis, perioperative hypertension, and atrial tachyarrhythmia. However, despite the clear links, there are missing links between the known hemodynamic effects and the reported outcome evidence, suggesting that further studies are needed for clarification. In this narrative review, we aim to discuss the hemodynamic effects and outcome evidence for CCBs, the links and missing links between these two domains, and the directions that merit future investigations.

Clinical Practice Guideline of Integrative Chinese and Western Medicine for Acute Myocardial Infarction

With increasing morbidity and mortality, acute myocardial infarction (AMI) has become one of the major causes of human death, leading to heavy burdens to individuals, families and society. Previous researches have found that though large amount of resources and great effort were devoted, no significant improvements were achieved in reducing the in-hospital mortality of AMI patients. Meanwhile, extensive studies about Chinese medicine (CM) have found that CM has special advantages in treating AMI patients. However, there is no standardized and unified clinical practice guideline (CPG) of CM for AMI. Therefore, a CPG with strict standard and generally acknowledgement is urgent to be established. This guideline was developed following the methodological process established by the World Health Organization Handbook for Guideline Development. Extensive search on clinical evidences including systematic review (SR), randomized controlled trial (RCT), observational study and case reports was launched, covering evidence of CM for AMI on several aspects, such as diagnosis, CM patterns, CM interventions on AMI and complications, cardiac rehabilitation and clinical pathway management. Besides, the application of Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach enabled the evaluation of evidence and formulation of grade of recommendation (GOR) and level of evidence (LOE). With the help of GOR and LOE, this CPG recommends the integrative CM and WM treatment method in AMI patients and provides useful information on medical decision for clinical physicians.

High-content phenotypic assay for proliferation of human iPSC-derived cardiomyocytes identifies L-type calcium channels as targets

Over 5 million people in the United States suffer from heart failure, due to the limited ability to regenerate functional cardiac tissue. One potential therapeutic strategy is to enhance proliferation of resident cardiomyocytes. However, phenotypic screening for therapeutic agents is challenged by the limited ability of conventional markers to discriminate between cardiomyocyte proliferation and endoreplication (e.g. polyploidy and multinucleation). Here, we developed a novel assay that combines automated live-cell microscopy and image processing algorithms to discriminate between proliferation and endoreplication by quantifying changes in the number of nuclei, changes in the number of cells, binucleation, and nuclear DNA content. We applied this assay to further prioritize hits from a primary screen for DNA synthesis, identifying 30 compounds that enhance proliferation of human induced pluripotent stem cell-derived cardiomyocytes. Among the most active compounds from the phenotypic screen are clinically approved L-type calcium channel blockers from multiple chemical classes whose activities were confirmed across different sources of human induced pluripotent stem cell-derived cardiomyocytes. Identification of compounds that stimulate human cardiomyocyte proliferation may provide new therapeutic strategies for heart failure.

Nonantithrombotic medical options in acute coronary syndromes: old agents and new lines on the horizon

Acute coronary syndromes (ACS) constitute a spectrum of clinical presentations ranging from unstable angina and non-ST-segment elevation myocardial infarction to ST-segment myocardial infarction. Myocardial ischemia in this context occurs as a result of an abrupt decrease in coronary blood flow and resultant imbalance in the myocardial oxygen supply-demand relationship. Coronary blood flow is further compromised by other mechanisms that increase coronary vascular resistance or reduce coronary driving pressure. The goals of treatment are to decrease myocardial oxygen demand, increase coronary blood flow and oxygen supply, and limit myocardial injury. Treatments are generally divided into disease-modifying agents or interventions that improve hard clinical outcomes and other strategies that can reduce ischemia. In addition to traditional drugs such as β-blockers and inhibitors of the renin-angiotensin-aldosterone system, newer agents have expanded the number of molecular pathways targeted for treatment of ACS. Ranolazine, trimetazidine, nicorandil, and ivabradine are medications that have been shown to reduce myocardial ischemia through diverse mechanisms and have been tested in limited fashion in patients with ACS. Attenuating the no-reflow phenomenon and reducing the injury compounded by acute reperfusion after a period of coronary occlusion are active areas of research. Additionally, interventions aimed at ischemic pre- and postconditioning may be useful means by which to limit myocardial infarct size. Trials are also underway to examine altered metabolic and oxygen-related pathways in ACS. This review will discuss traditional and newer anti-ischemic therapies for patients with ACS, exclusive of revascularization, antithrombotic agents, and the use of high-intensity statins.

The calcium-channel blocker controversy: historical perspective and important lessons for future pharmacotherapies. An international society of pharmacoepidemiology 'hot topic'

Reports of adverse events in association with calcium-channel blockers led to heated controversy over the safety and efficacy of these drugs, as well as to panic among the general public. At the 1998 International Conference of Pharmacoepidemiology, four experts were asked to summarize, and draw lessons from, the controversy's development. We conducted our own review in order to provide a broader historical perspective on the subject and to present the discussants' views within the framework of additional published opinions. Several years after the controversy's onset, many uncertainties still remain about the merits of CCBs. Yet the media scare generated by a few studies might have been prevented had investigators placed greater emphasis, particularly in their reports to the media, on the limitations of their observational and meta-analytic designs. These studies, however, did call attention to the persistent use of CCBs for off-label indications, and the imperative to improve clinician prescribing practices. Moreover, they showed the pitfalls of reliance on surrogate endpoints, stressing the need for data on major clinical outcomes-with funding a responsibility of the pharmaceutical industry-before approving drugs destined for widespread, long-term use. Attention to these lessons will do us well as we evaluate emerging pharmacotherapies. Copyright (c) 2000 John Wiley & Sons, Ltd.

Non ST-elevation acute coronary syndrome

INTRODUCTION

Non ST-elevation acute coronary syndrome (NSTE-ACS, here defined as unstable angina and non ST-elevation MI) is characterised by episodes of chest pain at rest or with minimal exertion, which increase in frequency or severity, often with dynamic ECG changes. Between 9% and 19% of people with NSTE-ACS die in the first 6 months after diagnosis, with about half of these deaths occurring within 4 weeks of diagnosis.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of: antiplatelet; antithrombin; anti-ischaemic; lipid-lowering; and invasive treatments? We searched: Medline, Embase, The Cochrane Library, and other important databases up to December 2009 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 32 systematic reviews, RCTs, or observational studies that met our inclusion criteria.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: aspirin, beta-blockers, calcium channel blockers, clopidogrel, direct thrombin inhibitors, glycoprotein IIb/IIIa inhibitors (oral or intravenous), heparin (low molecular weight, unfractionated), fondaparinux, nitrates, routine early cardiac catheterisation and revascularisation, statins, and warfarin.

Saving lives, money and resources: drug and CABG/PCI use after myocardial infarction in a Swedish record-linkage study

BACKGROUND

Drug costs are increasing despite the introduction of cheaper generic drugs. The aim of the present study was to analyse the entire costs of hospital care, out-patient care, and the cost of drugs for 16 months following a myocardial infarction (MI) to see to what extent drug costs contribute to the overall costs of care.

METHODS

Diagnoses and costs for care as well as mortality data obtained from the Västra Götaland Region, Sweden, and drug costs from the Swedish Board of Health and Welfare, were merged in a computer file. Patients registered from 1 July 2005 to 30 June 2006 were followed from 28 days after an MI, with follow-up until 31 October 2006.

RESULTS

Of 4,725 patients, 711 died before the start of the study and 721 during follow-up. Higher age [hazard ratio (HR, 95%CI) = 1.06 (1.05-1.07)], previous MI [HR = 1.31 (1.13-1.53)] and diabetes mellitus [HR = 1.34 (1.13-1.58)] were associated with increased mortality, which decreased with coronary interventions: CABG/PCI [HR = 0.19 (0.14-0.27)]. In a multivariable analysis, mortality was lower for patients taking simvastatin [HR = 0.62 (0.50-0.76)] and clopidogrel [HR = 0.58 (0.46-0.74)].

CONCLUSION

Costs for out-patient care accounted for 25% and drugs for 5% of total costs. If patients not treated with simvastatin or clopidogrel had received these drugs, an additional 154-306 lives might have been saved. Drug costs would be higher, but total costs lower. Thus, even expensive drugs may reduce overall costs.

Effect of early treatment with anti-hypertensive drugs on short and long-term mortality in patients with an acute cardiovascular event

BACKGROUND

Acute cardiovascular events represent a therapeutic challenge. Blood pressure lowering drugs are commonly used and recommended in the early phase of these settings. This review analyses randomized controlled trial (RCT) evidence for this approach.

OBJECTIVES

To determine the effect of immediate and short-term administration of anti-hypertensive drugs on all-cause mortality, total non-fatal serious adverse events (SAE) and blood pressure, in patients with an acute cardiovascular event, regardless of blood pressure at the time of enrollment.

SEARCH STRATEGY

MEDLINE, EMBASE, and Cochrane clinical trial register from Jan 1966 to February 2009 were searched. Reference lists of articles were also browsed. In case of missing information from retrieved articles, authors were contacted.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing anti-hypertensive drug with placebo or no treatment administered to patients within 24 hours of the onset of an acute cardiovascular event.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed risk of bias. Fixed effects model with 95% confidence intervals (CI) were used. Sensitivity analyses were also conducted.

MAIN RESULTS

Sixty-five RCTs (N=166,206) were included, evaluating four classes of anti-hypertensive drugs: ACE inhibitors (12 trials), beta-blockers (20), calcium channel blockers (18) and nitrates (18). Acute stroke was studied in 6 trials (all involving CCBs). Acute myocardial infarction was studied in 59 trials. In the latter setting immediate nitrate treatment (within 24 hours) reduced all-cause mortality during the first 2 days (RR 0.81, 95%CI [0.74,0.89], p<0.0001). No further benefit was observed with nitrate therapy beyond this point. ACE inhibitors did not reduce mortality at 2 days (RR 0.91,95%CI [0.82, 1.00]), but did after 10 days (RR 0.93, 95%CI [0.87,0.98] p=0.01). No other blood pressure lowering drug administered as an immediate treatment or short-term treatment produced a statistical significant mortality reduction at 2, 10 or >/=30 days. There was not enough data studying acute stroke, and there were no RCTs evaluating other acute cardiovascular events.

AUTHORS' CONCLUSIONS

Nitrates reduce mortality (4-8 deaths prevented per 1000) at 2 days when administered within 24 hours of symptom onset of an acute myocardial infarction. No mortality benefit was seen when treatment continued beyond 48 hours. Mortality benefit of immediate treatment with ACE inhibitors post MI at 2 days did not reach statistical significance but the effect was significant at 10 days (2-4 deaths prevented per 1000). There is good evidence for lack of a mortality benefit with immediate or short-term treatment with beta-blockers and calcium channel blockers for acute myocardial infarction.

The Secondary Prevention of myocardial infarction by drug treatment; excluding lipid lowering agents

About 10% of survivors of an acute myocardial infarction will die in the following year. Thereafter the risk declines but reinfarction is still an important cause of mortality and morbidity. The post infarction trials have clearly shown that the best proven agents to mitigate this toll are aspirin, beta adrenoceptor blockers, and verapamil (but not other calcium blockers, except diltiazem for non Q wave infarction). In the context of hypertension treatment these post infarction trials may have important lessons for drug selection and ancillary treatment since the majority of subjects will ultimately die of ischaemic heart disease. Although the newer agents such as ACE and renin inhibitors, newer calcium channel blockers and alpha blockers have many promising properties in terms of risk factor reduction, no convincing mortality data exists; it is needed. This review will deal with the known effects (both good and bad) of antihypertensive agents and will also review other drug strategies relevant to the hypertensive patient. It will also point out large areas of ignorance.

Development of newer calcium channel antagonists: therapeutic potential of efonidipine in preventing electrical remodelling during atrial fibrillation

Calcium channel antagonists are most frequently prescribed for the treatment of hypertension and the majority specifically inhibit the L-type Ca2+ channel. In order to prevent reflex sympathetic over activity caused by L-type calcium channel antagonists (calcium channel blockers [CCBs]), increasing attention has focused on the blockade of the T-type Ca2+ channel. The T-type Ca2+ channel is found in the kidney and can also appear in the ventricle of the heart when in failure. Therefore, the T-type Ca2+ channel is a possible new target for the treatment of nephropathy and heart failure. In clinical trials, the efficacy and safety of T-type CCBs in hypertension and chronic renal disease have been reported. It is well known that the T-type Ca2+ channel is present in the adult atrium and plays a role in the cardiac pacemaker, but recent experimental studies suggest that this current also promotes electrical remodelling of the atrium. Using efonidipine, a dual L- and T-type CCB, it has been demonstrated that atrial electrical remodelling can be diminished in dogs. Furthermore, the T-type Ca2+ channel has recently been found in the pulmonary veins, contributing to the pulmonary vein pacemaker activity and triggered activity. A variety of drugs having T-type CCB effects have been shown to be effective in the management of atrial fibrillation, suggesting that this channel may be a novel therapeutic target.

Pathophysiologic bases for adjunctive therapies in the treatment and secondary prevention of acute myocardial infarction

Postmyocardial infarction (MI) survival has been steadily improving. This improvement has been due, in part, to the actions of the adjunctive medical therapies for the treatment of MI. Aspirin, beta blockers, angiotensin-converting enzyme (ACE) inhibitors, and lipid-lowering agents have been shown to improve survival in the treatment and secondary prevention of MI. Nitrates have beneficial effects as well. These medications complement the reperfusion strategies through different mechanisms. Other adjunctive medical therapies, namely magnesium, antiarrhythmic agents, and calcium-channel blockers, have not been shown to improve mortality with routine post-MI use despite their theoretical benefits.

Verapamil use in patients with cardiovascular disease: an overview of randomized trials

BACKGROUND

Several reports have questioned the lack of safety data on calcium antagonists as a drug class. Because this drug class is heterogeneous, unique features of certain calcium antagonists may set them apart in terms of safety and efficacy.

HYPOTHESIS

With in excess of 7,000 person-years of observation from randomized clinical trials, verapamil was selected to evaluate whether there was evidence of harm in patients with cardiovascular disease.

METHODS

MEDLINE search of English-language articles, Science Citation Index, Current Contents, manual review of cited references, pharmaceutical files, and investigator correspondence was performed. Independent review of 66 articles identified 14 randomized, parallel-group studies for inclusion. Independent, duplicate assessments were made of patient outcomes and trial characteristics (including study design, treatment dosage and schedule, duration of treatment, inclusion criteria, and sample size). Standard meta-analytic techniques were employed for analysis and interpretation of results.

RESULTS

Based on over 4,000 person-years of observation, patients with acute myocardial infarction (MI) treated with verapamil had a decreased risk of nonfatal reinfarction compared with placebo (relative risk 0.79; 2-sided 95% confidence interval 0.65.0.97; p = 0.024). Verapamil had no significant effect on overall mortality compared with placebo (relative risk ranged from 0.93; 2-sided 95% confidence interval 0.78, 1.10; p = 0.40 to 0.86; 2-sided 95% confidence interval 0.71, 1.04; p = 0.13) depending on rules used to include or exclude patients from the pooling process. For the combined outcome of death or reinfarction, verapamil use was associated with a decreased risk compared with placebo (relative risk 0.82; 2-sided 95% confidence interval 0.70, 0.97; p = 0.016). In patients with angina involving a wide spectrum of disease severity, data were limited to 2,900 person-years of observation, and verapamil use did not appear to be associated with an apparent effect on mortality or MI. Data available from randomized studies of verapamil in patients with hypertension were too limited to reach conclusions (50 person-years of observation, with no deaths or MIs reported). Subgroups of hypertensive patients in two of the largest post-MI studies and the largest angina study, involving over 600 patients, yielded little useful added information.

CONCLUSIONS

In patients with MI, the risks of both nonfatal reinfarction and the combined outcome of death or nonfatal MI were reduced over intermediate-term follow-up among patients treated with verapamil compared with controls (p = 0.024 and p = 0.016, respectively). In patients with angina, no evidence for harm was noted, but in hypertension the data were too limited to draw conclusions. These findings support the need to distinguish among different calcium antagonist compounds and to emphasize the need for more data in patients with hypertension.

Acute coronary syndrome (unstable angina and non-ST elevation MI)

INTRODUCTION

In people with acute coronary syndrome (ACS) the incidence of serious adverse outcomes (such as death, acute myocardial infarction [MI], or refractory angina requiring emergency revascularisation) is 5-10% within the first 7 days and about 15% at 30 days. Between 5-14% of people with acute coronary syndrome die in the year after diagnosis, with about half of these deaths occurring within 4 weeks of diagnosis.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of: antiplatelet; antithrombin; anti-ischaemic; lipid-lowering; and invasive treatments? We searched: Medline, Embase, The Cochrane Library, and other important databases up to May 2007 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 32 systematic reviews, RCTs, or observational studies that met our inclusion criteria.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: aspirin, beta-blockers, calcium channel blockers, clopidogrel, direct thrombin inhibitors, glycoprotein IIb/IIIa inhibitors (oral or intravenous), heparin (low molecular weight, unfractionated), nitrates, routine early cardiac catheterisation and revascularisation, statins, and warfarin.

Thrombin receptor and ventricular arrhythmias after acute myocardial infarction

The mechanism mediating the development of ventricular arrhythmia (VA) after acute myocardial infarction (AMI) is still uncertain. Thrombin receptor (TR) activation has been proven to be arrhythmogenic in many other situations, and we hypothesize that it may participate in the genesis of post-AMI VA. Using a left coronary artery ligation rat model of AMI, we found that a local injection of hirudin into the left ventricle (LV) significantly reduced the ratio of VA durations to infarction sizing, whereas injection of thrombin receptor-activating peptide (TRAP) increased the ratios of VA duration to infarction sizing. The effects of TR activation on whole-cell currents were investigated in isolated myocytes. TRAP increased a glibenclamide-sensitive outward current. Pretreatment of rats with glibenclamide (4 mg/kg intraperitoneally) eliminated the effects of a local injection of TRAP on the ratios of VA durations to infarction sizing. TR mRNA and protein expression in the ischemic left ventricle had reached its peak by 20 min postligation in the rat AMI model (P < 0.05). TR-immunoreactive myocytes were observed in infarcted LV but were seldom seen in the right ventricle or in the normal heart. By 60 min, TR transcript levels had returned to control levels. We conclude that increased TR activation and expression in the infarcted LV after AMI may contribute to VA through a mechanism involving glibenclamide-sensitive potassium channels.

Impact of cilazapril on fibrinolytic system in hypertensive patients

Impaired fibrinolysis is associated with thromboembolic complications in hypertensive patients. Cardiovascular morbidity/mortality rates have been reported high even after lowering the elevated blood pressure with antihypertensive drugs. We investigated the effects of clinically used dosages of cilazapril on the fibrinolytic system in hypertensive patients. The present study was performed among 30 hypertensive patients (22 women, eight men), who received 2.5-5.0 mg cilazapril daily for 1 month. Before and after the cilazapril treatment, patients' venous blood was drawn for fibrinolytic tests. The fibrinolytic activity was examined utilizing the euglobulin clot lysis time and fibrin plate methods. Using the fibrin plate method, as compared with the pretreatment group, we observed a 57% increased activity in the hypertensive patients receiving cilazapril (P < 0.001). When assessed by the euglobulin clot lysis time method, the activity due to cilazapril treatment was found to be relatively low, although highly significant (approximately 20%, P < 0.001). Changes in fibrinolytic activity were observed in 23 (77%) hypertensive patients after cilazapril treatment; however, their blood pressure remained normal. The remaining seven patients' (23%) blood pressures and fibrinolytic activity did not change significantly after cilazapril treatment. In conclusion, we suggest that the observed differential fibrinolytic activity between the pre and post cilazapril treatment values is due to the plasminogen activators released from the vascular endothelium, which may have been stimulated by cilazapril. It appears that cilazapril is not only an angiotensin-converting enzyme inhibitor but also a stimulator for fibrinolytic activity, which may be an added component in reducing thromboembolic complications in hypertensive patients.

Management of patients with type 2 diabetes after acute coronary syndromes

Acute coronary syndromes are associated with a high risk for subsequent major cardiovascular events and with a risk for mortality that remains substantially increased for many months following the acute phase. Patients with type 2 diabetes mellitus are especially vulnerable and encounter excessive long-term mortality. Effective management of patients with type 2 diabetes following acute coronary syndromes requires aggressive multidisciplinary efforts for reduction of several risk factors, including meticulous control of blood glucose. The evidence for different medication and treatment strategies capable of improving the outcomes is reviewed and the currently available recommendations are summarised.

Clinical Pharmacology of Antihypertensive Therapy

Adequate control of blood pressure poses challenges for hypertensive patients and their physicians. Success rates of greater than 80% in reducing blood pressure to target values among high-risk hypertensive patients reported by several recent clinical trials argue that effective medications currently are available. Yet, only 34% of hypertensive patients in the United States are at their goal blood pressure according to the most recent national survey. Rational selection of antihypertensive drugs that target both the patient's blood pressure and comorbid conditions coupled with more frequent use of low-dose drug combinations that have additive efficacy and low adverse-effect profiles could improve significantly US blood pressure control rates and have a positive impact on hypertension-related cardiovascular and renal mortality and morbidity. This article reviews the pharmacokinetic and pharmacodynamic principles that underlie the actions of drugs in each of the classes of antihypertensive agents when used alone and in combination, provides practical pharmacologic information about the drugs most frequently prescribed for treatment of hypertension in the outpatient setting, and summarizes the current data influencing the selection of drugs that might be used most effectively in combination for the majority of hypertensive patients whose blood pressures are not controlled adequately by single-drug therapy.

Can a marker be a surrogate for development of cancer, and would we know it if it exists?

Carcinogenesis proceeds through a very long preclinical period. Our collective hope is that multiple opportunities exist for chemoprevention to arrest or reverse progression towards malignancy. In the hope of faster progress with fewer subjects and lower total cost, much effort is being expended on the search for reliable biomarkers to predict the likelihood of developing cancer and/or to signal the effectiveness of chemopreventive therapy. Considerable attention is paid to identifying those markers that can act as surrogate markers for cancer development, since favorable modulation of the surrogate end-point biomarker (SEBM) may demonstrate effectiveness of a putative preventive treatment. However, the complexity of the biology challenges our ability to measure the effectiveness of attempts to arrest or reverse carcinogenesis, other than through costly and time-consuming prospective trials with disease state as the endpoint. Despite much work, to date no prehistologic biological or molecular intermediate marker has been validated for sporadic cancers. Several factors accounting for the difficulties encountered in SEBM development are reviewed. Discussion is focused on the common thread of the complexity of the underlying biological changes in carcinogenesis limiting the effectiveness of any single biomarker. Additionally, the incidence of sporadic cancers is also low, further limiting the positive predictive value of any putative prognostic marker. Recent successes in development of chemopreventive agents show the concept is valid and worth pursuing, but the current strategies to develop biochemical and genetic markers to identify surrogate biomarkers is flawed, and need to be reassessed in light of the difficulties faced over the last 20 years.

Calcium antagonists

Calcium antagonists were introduced for the treatment of hypertension in the 1980s. Their use was subsequently expanded to additional disorders, such as angina pectoris, paroxysmal supraventricular tachycardias, hypertrophic cardiomyopathy, Raynaud phenomenon, pulmonary hypertension, diffuse esophageal spasms, and migraine. Calcium antagonists as a group are heterogeneous and include 3 main classes--phenylalkylamines, benzothiazepines, and dihydropyridines--that differ in their molecular structure, sites and modes of action, and effects on various other cardiovascular functions. Calcium antagonists lower blood pressure mainly through vasodilation and reduction of peripheral resistance. They maintain blood flow to vital organs, and are safe in patients with renal impairment. Unlike diuretics and beta-blockers, calcium antagonists do not impair glucose metabolism or lipid profile and may even attenuate the development of arteriosclerotic lesions. In long-term follow-up, patients treated with calcium antagonists had development of less overt diabetes mellitus than those who were treated with diuretics and beta-blockers. Moreover, calcium antagonists are able to reduce left ventricular mass and are effective in improving anginal pain. Recent prospective randomized studies attested to the beneficial effects of calcium antagonists in hypertensive patients. In comparison with placebo, calcium antagonist-based therapy reduced major cardiovascular events and cardiovascular death significantly in elderly hypertensive patients and in diabetic patients. In several comparative studies in hypertensive patients, treatment with calcium antagonists was equally effective as treatment with diuretics, beta-blockers, or angiotensin-converting enzyme inhibitors. From these studies, it seems that a calcium antagonist-based regimen is superior to other regimens in preventing stroke, equivalent in preventing ischemic heart disease, and inferior in preventing congestive heart failure. Calcium antagonists are also safe and effective as first-line or add-on therapy in diabetic hypertensive patients. Heart rate-lowering calcium antagonists (verapamil, diltiazem) may have an edge over the dihydropyridines in post-myocardial infarction patients and in diabetic nephropathy. Thus, calcium antagonists may be safely used in the management of hypertension and angina pectoris.

An application of meta-analysis techniques in the evaluation of adverse experiences with antihypertensive agents

PURPOSE

To investigate the profiles of adverse events (AEs) in randomized controlled trials of antihypertensive agents therapy with the technique of meta-analysis.

METHODS

A total of 620 articles were selected from MEDLINE, EMBASE, JAPIC-DOC, JMEDICINE and manual searching. Two independent reviewers examined the 620 selected articles according to the following criteria: (1) the methods of randomization, (2) making for allocating treatments, (3) therapeutic class of drugs, (4) sample sizes, (5) duration of the treatment, (6) primary endpoint, (7) reporting method for all adverse events, (8) method of monitoring AEs, and (9) incidence rates of all reported AEs. To combine the risk difference and risk ratios of incidence between CCBs and beta blockers or diuretics, the method of DerSimonian and Laird based on random effect model was applied.

RESULTS

A total of 3073 patients were included in this meta-analysis of serious adverse events (SAEs). There was no significant difference in the total incidence of SAEs between CCBs and diuretics or between CCBs and beta blockers. We found that patients treated with CCBS had 0.14% fewer SAEs compared with the patients treated with diuretics. Contrarily, the patients treated with CCBs had 0.29% more SAEs compared with the patients treated with beta blockers. There was a significant difference between the patients treated with CCBs and those treated with diuretics in the symptoms with headache and oedema. With respect to the comparison between CCBs and beta blockers, flushing occurred 8.75% more frequently in the CCBs group than in the beta blockers group.

CONCLUSION

A meta-analysis can be applied to safety analyses of data obtained in clinical trials if all of the RCT articles used include a complete description of adverse experiences.

Efficacy of Calcium Channel Blocker in the Secondary Prevention of Myocardial Infarction-Retrospective Analysis of the 10-Year Prognosis of Coronary Thrombolysis-Treated Patients-

BACKGROUND

Calcium channel blockers (CCBs) may have a positive influence on the long-term prognosis of Japanese patients with ischemic heart disease.

METHODS AND RESULTS

The effect of nifedipine-retard (NR) (n=202) compared with that of non-CCB treatment (n=92) on the secondary prevention of myocardial infarction (MI) was retrospectively investigated in patients who had survived acute MI between 1987 and 1996. The primary endpoint was the occurrence of cardiac death or non-fatal MI. The median follow-up was 6.3+/-2.4 years. The incidence of cardiac events was 8.9% in the NR group and 14.1% in the non-CCBs group (p=0.14, odds ratio (OR): 0.584, 95% confidence interval (CI): 0.286-1,193). However, subanalysis revealed that NR significantly reduced the incidence of cardiac events in patients aged less than 55 years (4.2 vs 18.2%, p=0.016, OR: 0.180, 95%CI: 0.045-0.721) and those who did not smoke (8.6 vs 16.4%, p=0.048, OR: 0.462, 95%CI: 0.203-0.999).

CONCLUSION

Although this was a retrospective analysis, it showed that NR did not cause an increase in the incidence of cardiac events in post-MI patients; it even prevented cardiac events, especially in those who were less than 55 years of age and in non-smokers, suggesting the potential usefulness of CCBs in the secondary prevention of MI in Japan.

Evolving role of calcium antagonists in the management of hypertension

What, if anything, should physicians make of these apparently disparate hazards in a group of drugs that they prescribe so widely? The authors, and many of our colleagues, still believe that most patients clearly benefit from the judicious use of calcium antagonists. Reports of several large, powered prospective, randomized outcome studies including ALLHAT commend the use of long-acting calcium antagonists that, by virtue of their ability to attain more gradual and sustained plasma levels, do not evoke reactive sympathetic activation and consequently are safe. Concomitantly, such formulations should promote increased patient compliance and thereby favorably influence hypertension-related morbidity and mortality.

The Differences Between ACE Inhibitor-Treated and Calcium Channel Blocker-Treated Hypertensive Patients

Large-scale outcome trials have demonstrated that blood pressure reduction with angiotensin-converting enzyme (ACE) inhibitors or calcium channel blockers (CCBs) is associated with reduced cardiovascular complications in hypertension. Comparative trials against conventional drugs and between ACE inhibitors and CCBs have failed to reveal conclusive differences in cause-specific outcomes. Studies in high-risk patients suggest that ACE inhibitors are superior to CCBs and other drugs in protection against cardiovascular events and renal disease. Very long-term prospectively collected observational data from the Glasgow Blood Pressure Clinic and the UK General Practice Research Database strongly support an advantage of ACE inhibitors over CCBs for cardiovascular morbidity and mortality. Considering all the available information, it can be concluded that the use of CCBs in the routine therapy of hypertension cannot be recommended while wider use of ACE inhibitors, along with low-dose diuretics and beta blockers, appears justified.

Antiplatelet activity of semotiadil fumarate

Calcium antagonists are known to exert antiplatelet activity. Semotiadil fumarate (SD-3211), a new benzothiazine, was therefore examined for its antiplatelet activity. The inhibitory activity on adenosine diphosphate (ADP)-, collagen-, arachidonic acid (AA)-, and platelet activating factor (PAF)-induced platelet aggregation after the 1-, 30-, 60- and 120-min incubation at concentrations ranging from 1 x 10(-3), 1 x 10(-4), 1 x 10(-5), 1 x 10(-6) and 1 x 10(-7) was examined. The data were compared with those using diltiazem, nifedipine and amlodipine under identical conditions in blood from eight healthy volunteers (four males, four females; aged 23-36 years) and eight hypertensive patients (four males, four females; aged 31-46 years). Semotiadil showed a dose-dependent inhibition of platelet aggregation in vitro with all the agents examined. Using the various aggregation-inducing agents, the dose-dependent inhibitory action was comparable for all the compounds tested. The antiaggregatory potency was in the order diltiazem, semotiadil, amlodipine and nifedipine. The incubation period did not significantly affect the antiaggregatory effect. No difference between platelets derived from healthy volunteers and hypertensive patients was noted. These findings indicate potent antiplatelet activity of the new calcium antagonist semotiadil.

Cilnidipine as an agent to lower blood pressure without sympathetic nervous activation as demonstrated by iodine-123 metaiodobenzylguanidine imaging in rat hearts

BACKGROUND

Administration of short-acting antihypertensive agents to patients with ischemic heart disease results in increased sympathetic nervous activity and is associated with worsened outcomes. Cilnidipine is an agent which blocks not only L-type calcium channels at the smooth muscle in the artery, but also N-type calcium channels at the presynaptic terminal. The goal of the present study was to determine the effect of cilnidipine on sympathetic nervous activity as on agent which blocks both L-type and N-type calcium channels at the presynaptic terminal, on sympathetic nervous activity in an experimental rat model using iodine-123 metaiodobenzylguanidine (MIBG) myocardial imaging.

METHODS

Fourteen-week-old Wistar-Kyoto rats were divided into 3 separate groups: CTR group (control: distilled water administered), Nif group (nifedipine administered), or Cil group (cilnidipine administered). Agents were administered via a stomach tube, followed by injection of MIBG via the femoral vein. Systolic blood pressure (SBP) and heart rate (HR) were measured by tail-cuff plethysmography just prior to administration of antihypertensive drugs and 150 minutes later. Initial imaging (Ce) and delayed imaging (Cd) were defined as the sum of density counts in the region of interest created by adjusting to myocardial edge, and were corrected for both physical decay and weight. The myocardial washout rate (WR) was defined as the percent change in the count density from the initial to delayed images.

RESULTS

Significant decreases in SBP were seen in the Nif group (from 132 +/- 3 mmHg to 85 +/- 5 mmHg, p < 0.0001) and the Cil group (from 128 +/- 4 mmHg to 92 +/- 7 mmHg, p = 0.0008), whereas no significant change in SBP was noted in the CTR group (from 123 +/- 5 mmHg to 127 +/- 3 mmHg). HR significantly increased in the Nif group (from 290 +/- 12/min to 378 +/- 14/min, p < 0.0001) but not in the CTR (from 278 +/- 3/min to 300 +/- 6/min) or Cil (from 291 +/- 6/min to 303 +/- 5/min) groups. WR was significantly greater in the Nif group (64.7 +/- 0.5%) when compared to the CTR (56.4 +/- 1.2%, p = 0.0031) or the Cil (55.4 +/- 2.2%, p = 0.0016) groups.

CONCLUSION

In contrast to nifedipine, administration of cilnidipine did not result in increased myocardial sympathetic nervous activation.