Effect of calcium antagonists on plasma norepinephrine levels, heart rate, and blood pressure

Preventing Recurrent Preeclampsia by Tailored Treatment of Nonphysiologic Hemodynamic Adjustments to Pregnancy

[Figure: see text].

Effects of antihypertensive medication and high-intensity interval training in hypertensive metabolic syndrome individuals

Pharmacological and non-pharmacological therapies are simultaneously prescribed when treating hypertensive individuals with elevated cardiovascular risk (ie, metabolic syndrome individuals). However, it is unknown if the interactions between antihypertensive medication (AHM) and lifestyle interventions (ie, exercise training) may result in a better ambulatory blood pressure (ABP) control. To test this hypothesis, 36 hypertensive individuals with metabolic syndrome (MetS) under long-term prescription with AHM targeting the renin-angiotensin-aldosterone system (RAAS) were recruited. Before and after 4 months of high-intensity interval training (HIIT), participants completed two trials in a double-blind, randomized order: (a) placebo trial consisting of AHM withdrawal for 3 days and (b) AHM trial where individuals held their habitual dose of AHM. In each trial, 24-h mean arterial pressure (MAP) was monitored and considered the primary study outcome. Secondary outcomes included plasma renin activity (PRA) and aldosterone concentration to confirm withdrawal effects on RAAS, along with the analysis of urine albumin-to-creatinine ratio (UACR) to assess kidney function. The results showed main effects from AHM and HIIT reducing 24-h MAP (-5.7 mmHg, p < 0.001 and -2.3 mmHg, p = 0.007, respectively). However, there was not interaction between AHM and HIIT on 24-h MAP (p = 0.240). There was a main effect of AHM increasing PRA (p < 0.001) but no effect on plasma aldosterone concentration (p = 0.368). HIIT did not significantly improve RAAS hormones or the UACR. In conclusion, AHM and HIIT have independent and additive effects in lowering ABP. These findings support the combination of habitual AHM with exercise training with the goal to reduce ABP in hypertensive MetS individuals.

Differential effects on out-of-hospital cardiac arrest of dihydropyridines: real-world data from population-based cohorts across two European countries

AIMS

Various drugs increase the risk of out-of-hospital cardiac arrest (OHCA) in the general population by impacting cardiac ion channels, thereby causing ventricular tachycardia/fibrillation (VT/VF). Dihydropyridines block L-type calcium channels, but their association with OHCA risk is unknown. We aimed to study whether nifedipine and/or amlodipine, often-used dihydropyridines, are associated with increased OHCA risk, and how these drugs impact on cardiac electrophysiology.

METHODS AND RESULTS

We conducted a case-control study with VT/VF-documented OHCA cases with presumed cardiac cause from ongoing population-based OHCA registries in the Netherlands and Denmark, and age/sex/index date-matched non-OHCA controls (Netherlands: PHARMO Database Network, Denmark: Danish Civil Registration System). We included 2503 OHCA cases, 10 543 non-OHCA controls in Netherlands, and 8101 OHCA cases, 40 505 non-OHCA controls in Denmark. To examine drug effects on cardiac electrophysiology, we performed single-cell patch-clamp studies in human-induced pluripotent stem cell-derived cardiomyocytes. Use of high-dose nifedipine (≥60 mg/day), but not low-dose nifedipine (<60 mg/day) or amlodipine (any-dose), was associated with higher OHCA risk than non-use of dihydropyridines [Netherlands: adjusted odds ratios (ORadj) 1.45 (95% confidence interval 1.02-2.07), Denmark: 1.96 (1.18-3.25)] or use of amlodipine [Netherlands: 2.31 (1.54-3.47), Denmark: 2.20 (1.32-3.67)]. Out-of-hospital cardiac arrest risk of (high-dose) nifedipine use was not further increased in patients using nitrates, or with a history of ischaemic heart disease. Nifedipine and amlodipine blocked L-type calcium channels at similar concentrations, but, at clinically used concentrations, nifedipine caused more L-type calcium current block, resulting in more action potential shortening.

CONCLUSION

High-dose nifedipine, but not low-dose nifedipine or any-dose amlodipine, is associated with increased OHCA risk in the general population. Careful titration of nifedipine dose should be considered.

Comparison of calcium-channel blockers for long-term clinical outcomes in patients with vasospastic angina

BACKGROUND/AIMS

Calcium channel blockers (CCBs) are the most widely prescribed medication for patients with vasospastic angina (VA). However, few studies have compared the prognosis of VA patients who are prescribed different CCBs.

METHODS

We enrolled 2,960 patients who received provocation test prospectively in 11 university hospitals in Korea. We divided 1,586 patients received four major CCBs into two groups: a first generation CCB (diltiazem and nifedipine) group and a second generation CCB (amlodipine and benidipine) group. Primary outcome was time to events of composite of death from any cause, acute coronary syndrome (ACS) and symptomatic arrhythmia during 3-year follow-up. We also compared the effect of each CCB on the control of angina symptoms.

RESULTS

There was no difference of the primary outcome among the two groups with a cumulative incidence rate of 5.4%, 2.9%, and a person-month incidence rate of 2.33 and 1.26, respectively (hazard ratio [HR], 0.54; 95% confidence interval [CI], 0.25 to 1.17; p = 0.120, as reference with the 1st generation CCBs). The incidence of ACS was significantly lower in 2nd generation CCBs group with a person-month incidence rate of 1.66 vs. 0.35 (HR, 0.22; 95% CI, 0.05 to 0.89; p = 0.034). Use of benidipine showed a significant better control of angina symptom compared with diltiazem for 3 years (odds ratio, 0.17; 95% CI, 0.09 to 0.32; p < 0.0001 at 3rd year).

CONCLUSION

The first and second generation CCB groups did not differ in terms of composite outcome occurrence. However, the ACS incidence rate was significantly lower in the users of the 2nd generation CCBs.

Study protocol for the randomized controlled EVA (early vascular adjustments) trial: tailored treatment of mild hypertension in pregnancy to prevent severe hypertension and preeclampsia

BACKGROUND

In contrast to severe gestational hypertension, it is questioned whether antihypertensive medication for mild to moderate gestational hypertension prevents adverse maternal and offspring outcomes. Hypertensive drugs halve the risk of severe hypertension, but do not seem to prevent progression to preeclampsia or reduce the risk of complications in offspring. In fact, beta-blockers, a first line therapy option, are suspected to impair foetal growth. Disappointing effects of antihypertensive medication can be anticipated when the pharmacological mode of action does not match the underlying haemodynamic imbalance. Hypertension may result from 1) high cardiac output, low vascular resistance state, in which beta blockade is expected to be most effective, or 2) low cardiac output, high vascular resistance state where dihydropyridine calcium channel blockers or central-acting alpha agonists might be the best corrective medication. In the latter, beta-blockade might be maternally ineffective and even contribute to impaired foetal growth by keeping cardiac output low. We propose a randomized controlled trial to determine whether correcting the haemodynamic imbalance in women with mild to moderate hypertension reduces the development of severe hypertension and/or preeclampsia more than non-pharmacological treatment does, without alleged negative effects on foetal growth.

METHODS

Women diagnosed with mild to moderate hypertension without proteinuria or signs of other organ damage before 37 weeks of pregnancy are invited to participate in this randomized controlled trial. Women randomized to the intervention group will be prescribed tailored antihypertensive medication, using a simple diagnostic and treatment algorithm based on the mean arterial pressure/heart rate ratio, which serves as an easy-to-determine proxy for maternal circulatory state. Women randomized to the control group will receive non-pharmacological standard care according to national and international guidelines. In total, 208 women will be randomized in a 1:1 ratio. The primary outcome is progression to severe hypertension and preeclampsia and the secondary outcomes are adverse maternal and neonatal outcomes.

DISCUSSION

This trial will provide evidence of whether tailoring treatment of mild to moderate gestational hypertension to the individual haemodynamic profile prevents maternal disease progression.

TRIAL REGISTRATION

NCT02531490 , registered on 24 August 2015.

Treatment effect of lacidipine and amlodipine on clinic and ambulatory blood pressure and arteria stiffness in a randomised double-blind trial

PURPOSE

In a randomised, double-blind trial, we investigated effects of lacidipine on clinic and ambulatory blood pressure (BP) and arterial stiffness in patients with mild-to-moderate hypertension, as compared with amlodipine.

MATERIALS AND METHODS

Previously untreated and treated patients (n = 269, 50-80 years of age) with clinic hypertension (a clinic systolic/diastolic BP 140-180/<110 mmHg and <160/100 mmHg, respectively) were randomly assigned to double-dummy treatment with lacidipine (4-6 mg/day) or amlodipine (5-7.5 mg/day) for 20 weeks. The primary efficacy variable was the change in 24-h ambulatory systolic BP at 20 weeks of treatment. Arterial stiffness was measured as brachial-ankle pulse wave velocity (PWV).

RESULTS

After 20 weeks of treatment, 24-h systolic BP decreased from 141.3 ± 14.0 and 138.3 ± 12.8 mmHg at baseline, respectively, in the lacidipine (n = 134) and amlodipine groups (n = 135), by a least square mean (±SE) change of 15.2 ± 1.3 and 15.5 ± 1.3 mmHg, respectively, with a between-group difference (95% confidence interval [CI]) of 0.3 mmHg (-3.4 to 4.1, p = 0.86). Similar results were observed for other ambulatory BP components and clinic BP. Clinic and ambulatory pulse rate did not significantly change in either group (p ≥ 0.21). PWV decreased significantly (p < 0.001) from baseline in both groups, with a non-significant between-group difference of 0.24 m/s (p = 0.45). The incidence rate of adverse events was 30.3% (n = 40) and 27.5% (n = 36) in the lacidipine and amlodipine groups, respectively (p = 0.61). No serious adverse event occurred in the trial.

CONCLUSIONS

Lacidipine effectively lowers clinic and ambulatory BP in patients with mild-to-moderate hypertension and significantly improves arterial stiffness, similarly as amlodipine.

Randomized Dose-Response Study of the New Dual Endothelin Receptor Antagonist Aprocitentan in Hypertension

Supplemental Digital Content is available in the text.

This study examined the dose-response characteristics of aprocitentan, a dual endothelin A/endothelin B receptor antagonist, in patients with essential hypertension. In a randomized, double-blind, parallel study design, eligible patients with a sitting diastolic blood pressure (BP) of 90–109 mm Hg received aprocitentan 5, 10, 25, or 50 mg, placebo, or lisinopril 20 mg as a positive control once daily for 8 weeks. Multiple automated office BP readings were obtained with patients resting unattended (unattended automated office BP) at baseline, weeks 2, 4, and 8. Ambulatory BP was monitored for 24 hours at baseline and week 8. After a single-blind placebo run-in period, 490 eligible patients were randomized to the double-blind phase, with 409 patients completing 8 weeks of therapy per protocol. Aprocitentan 10, 25, and 50 mg decreased sitting systolic/diastolic unattended automated office BP from baseline to week 8 (placebo-corrected decreases: 7.05/4.93, 9.90/6.99, and 7.58/4.95 mm Hg, respectively, P≤0.014 versus placebo), compared with an unattended automated office BP reduction of 4.84/3.81 mm Hg with lisinopril 20 mg. For patients with valid ambulatory BP, aprocitentan 10, 25, and 50 mg significantly decreased placebo-corrected 24-hour BP by 3.99/4.04, 4.83/5.89, and 3.67/4.45 mm Hg, respectively. Incidence of adverse events was similar in the aprocitentan groups (22.0%–40.2%) and the placebo group (36.6%). Aprocitentan produced dose-dependent decreases in hemoglobin, hematocrit, albumin, and uric acid, an increase in estimated plasma volume, but no change in weight versus placebo. These findings support further investigation of aprocitentan at doses of 10 to 25 mg in hypertension.

Effects of ischaemic conditioning on tissue oxygen saturation and heart rate variability: an observational study

Objective

Ischaemic conditioning (IC) has organ-protective effects, but its clinical results have been inconsistent. Tissue oxygen saturation (StO₂) and heart rate variability (HRV) reflect peripheral microcirculation and autonomic nervous system activity, but their changes during IC have not been well documented. We assessed StO₂ and HRV during IC in patients undergoing cardiac surgery and healthy volunteers.

Methods

Ten patients undergoing cardiac surgery and 10 healthy male volunteers underwent remote IC (four 5-minute cycles of ischaemia/reperfusion) applied to the upper arm. Changes in StO₂ at the thenar eminence and HRV according to the R-R intervals were recorded during IC.

Results

The lowest StO₂ during ischaemia significantly decreased in patients and significantly increased in volunteers. Among the HRV parameters, the low-frequency domain, which corresponds to sympathetic activity, significantly increased after IC in volunteers but not in patients. Other variables were similar between the groups.

Conclusions

These results suggest that the minimum tissue oxygen content is depleted during ischaemia in patients and preserved in healthy volunteers. Sympathetic nervous activity seems to increase after IC in healthy volunteers but remains unaffected in patients. Thus, IC may act differently between patients undergoing cardiac surgery and healthy subjects.

Effects of Long- and Intermediate-Acting Dihydropyridine Calcium Channel Blockers in Hypertension: A Systematic Review and Meta-Analysis of 18 Prospective, Randomized, Actively Controlled Trials

BACKGROUND

Dihydropyridine calcium channel blockers are a heterogeneous group of antihypertensive drugs. Long-acting dihydropyridine agent amlodipine is widely used for monotherapy and combination therapy for hypertension in clinical practice, while intermediate-acting dihydropyridine agents have shown inconsistent results in randomized clinical trials (RCTs).

METHODS AND RESULTS

A meta-analysis of 18 RCTs enrolling a total of 80,483 patients with hypertension followed for a mean of 51.4 months was performed. Amlodipine therapy was associated with 25% higher risk of heart failure (relative risk [RR]: 1.25, 95% confidence interval [CI], 1.05-1.49, P = .019) but 17% lower risk of stroke (RR: 0.83, [95% CI, 0.72-0.97], P = .009) without statistically significant effect on acute myocardial infarction (AMI) compared to major alternative antihypertensive therapy (MAAT), including β-blocker, diuretic, angiotensin-converting enzyme inhibitor, or angiotensin-receptor blocker. Intermediate-acting dihydropyridine calcium channel blocker therapy was associated with 25% higher risk of heart failure (RR: 1.25, [95% CI, 1.06-1.47], 0.005, P = .005) and 26% higher risk of AMI (RR: 1.26, [95% CI, 1.05-1.51], 0.019, P = .019) compared to MAAT. Results of the subgroup analysis suggested that the intermediate-acting dihydropyridine calcium channel blocker was associated with higher risk of heart failure (RR: 1.30, [95% CI, 1.08-1.56], P = .005) and AMI (RR: 1.50, [95% CI, 1.01-2.22], P = .043) compared to renin-angiotensin system blockers and a trend toward higher risk of AMI (RR: 1.17, [95% CI, 0.99-1.38], P = .064) compared to conventional therapy, including β-blockers and diuretics. Meta-regression analyses suggested that long-acting dihydropyridine calcium channel blocker is associated with lower risk of AMI ( B: -0.327, [95% CI, -0.530 to -0.123], P = .002) with a trend toward lower risk of stroke ( B: -0.203, [95% CI, -0.410 to 0.003] P = .054).

CONCLUSIONS

This study suggests that Amlodipine offers greater protection against major complications of hypertension compared to intermediate-acting dihydropyridine calcium channel blockers.

Approach to Antihypertensive Therapy

Antihypertensive agents are commonly prescribed by physicians to prevent the long-term mortality from chronic hypertension. They are also given to improve survival in a number of conditions (eg, heart failure, coronary artery disease), independent of the effect on blood pressure. Several classes of antihypertensives are available with unique pharmacologic characteristics and adverse effects. Not all agents in the same class have identical effects, and careful selection of drugs based on the comorbid conditions is recommended.

Effects of diltiazem on sympathetic activity in patients with aneurysmal subarachnoid hemorrhage

This study evaluated the effect of diltiazem, a calcium antagonist, on sympathetic activity in patients with aneurysmal subarachnoid hemorrhage (SAH) during the hyperacute stage. Of patients with aneurysmal SAH who underwent aneurysm repair between August 2008 and June 2011, 119 consecutive patients were enrolled in this prospective study. On admission, patients were assigned to an antihypertensive treatment receiving continuous infusion of diltiazem (67 patients) or nicardipine (52 patients). Plasma levels of adrenaline (AD), noradrenaline (NA), and dopamine (DP) were repeatedly measured using high-performance liquid chromatography (HPLC). There were no significant differences in patient characteristics or aneurysm topography between the two groups. In all patients, acute surge of catecholamines was observed with mutual correlation. However, patients receiving diltiazem exhibited a significantly lower plasma concentration of DP than those receiving nicardipine, 3 and 6 h after admission. A similar trend was observed for NA, but the difference was not significant at 6 h. Conversely, the concentration of AD was similar between the two groups. Diltiazem may suppress sympathetic activity in the hyperacute stage of aneurysmal SAH. Further studies are needed to verify the beneficial effect of diltiazem in patients with SAH.

Diltiazem reduces mortality and breakdown of ATP in red blood cell induced by isoproterenol in a freely moving rat model in vivo

The benefit of calcium channel blockers for cardiovascular prevention against heart attack and stroke has not been firmly supported. We investigated the possible cardiovascular protective effect of diltiazem (DTZ) against injury induced by isoproterenol using a freely moving rat model in vivo. Sprague Dawley rats were injected subcutaneously (sc) with either 5 or 10 mg/kg of DTZ, or saline as control, twice daily for five doses. One hour after the last injection, a single dose of isoproterenol (30 mg/kg) was injected sc to each rat. Blood samples were collected serially for 6 h for measurement of adenine nucleotides (ATP, ADP and AMP) in red blood cell (RBC) by a validated HPLC. The study has shown isoproterenol induced 50% mortality and also increased RBC concentrations of AMP from 0.04 ± 0.02 to 0.29 ± 0.21 mM at the end of the experiment (p < 0.05). Treatment with 10 mg/kg of DTZ reduced mortality from 50% to <20% and attenuated the increase of RBC concentrations of AMP from +0.25 ± 0.22 in the control rats to +0.072 ± 0.092 mM (p < 0.05). The study concluded that 10 mg/kg of DTZ reduced mortality and breakdown of ATP induced by isoproterenol in rats.

Efficacy of olmesartan/amlodipine combination therapy in reducing ambulatory blood pressure in moderate-to-severe hypertensive patients not controlled by amlodipine alone

This previously unpublished, preplanned analysis investigated the efficacy of the olmesartan/amlodipine combination at different doses on 24-h blood pressure (BP) control, as well as assessed trough estimation of trough-to-peak ratio (TPR) and smoothness index (SI). Ambulatory BP monitoring was performed in patients with moderate-to-severe hypertension whose BP was inadequately controlled after 8 weeks' treatment with amlodipine 5 mg. Patients were randomized to continue with amlodipine 5 mg or to receive olmesartan/amlodipine 10/5, 20/5 or 40/5 mg for 8 weeks (Period II). Patients not achieving BP control were uptitrated to a more powerful regimen for another 8 weeks (Period III). During Period II, each olmesartan/amlodipine combination reduced 24-h systolic and diastolic BP (SBP/DBP), as well as morning and early morning SBP/DBP, significantly more than amlodipine 5 mg (P<0.001 for all). TPRs were higher in each olmesartan/amlodipine group than with amlodipine 5 mg, and SI values showed dose-related increases; olmesartan/amlodipine 40/5 mg produced a significantly higher SI for SBP and DBP (1.55 and 1.33, respectively) than amlodipine 5 mg (0.96 and 0.77, respectively, P<0.0001 for each). During Period III, uptitrated patients showed further BP reductions, which were largest in those on olmesartan/amlodipine 40/10 mg. SI values increased in uptitrated patients and were highest with olmesartan/amlodipine 40/10 mg (SBP 1.62/DBP 1.41). The olmesartan/amlodipine combination effectively reduces BP over 24 h, including the morning hours, in a dose-related manner. Compared with amlodipine alone, the olmesartan/amlodipine combination has a better 24-h coverage (TPR) and a dose-related improvement in BP lowering homogeneity (SI).

The autonomic nervous system and renal physiology

Research in resistant hypertension has again focused on autonomic nervous system denervation – 50 years after it had been stopped due to postural hypotension and availability of newer drugs. These (ganglionic blockers) drugs have all been similarly stopped, due to postural hypotension and yet newer antihypertensive agents. Recent demonstration of the feasibility of limited regional transcatheter sympathetic denervation has excited clinicians due to potential therapeutic implications. Standard use of ambulatory blood pressure recording equipment may alter our understanding of the diagnosis, potential treatment strategies, and health care outcomes – when faced with patients whose office blood pressure remains in the hypertensive range – while under treatment with three antihypertensive drugs at the highest tolerable doses, plus a diuretic. We review herein clinical relationships between autonomic function, resistant hypertension, current treatment strategies, and reflect upon the possibility of changes in our approach to resistant hypertension.

A review of the gastrointestinal therapeutic system (GITS) formulation and its effectiveness in the delivery of antihypertensive drug treatment (focus on nifedipine GITS)

Hypertension treatment guidelines do not discriminate within drug classes and, furthermore, do not consider whether or not all of the formulations of any given drug licensed for once-daily administration can be considered to be therapeutically interchangeable. This article focuses on this issue with respect to nifedipine and the development of the gastrointestinal therapeutic system (GITS) formulation. Nifedipine GITS is regarded as the gold standard once-daily formulation of nifedipine and, as such, it is anticipated that alternative formulations will be therapeutically equivalent to nifedipine GITS. In general, this depends on demonstrating pharmacokinetic bioequivalence. This article is intended to focus attention on generic substitution and, in particular, on aspects of the scientific basis for the substitution of generic products in place of branded products. Such substitution is required for cost-saving or cost-containment reasons and is justified on the basis that the generic (substitute) drug is “therapeutically” equivalent to the branded drug. Unfortunately, there are serious shortcomings in the current methods of assessment insofar as they are typically based on statistical comparisons of average pharmacokinetic parameter values, using arbitrary comparative criteria. This article illustrates the shortcomings of the current approaches to generic substitution and concludes that, in regulatory terms, either more rigorous pharmacokinetic criteria are required or pharmacodynamic indices should be added to reinforce the regulatory criteria. Generic substitution is a balancing act but, at the moment, the cost issue is dominant. To restore the balance, equivalent efficacy must be confirmed. At present, therefore, in the absence of such regulatory rigor, the obvious course is to prefer the branded product, the therapeutic efficacy of which (including outcome benefits) has been established.

Long-acting dihydropyridine calcium-channel blockers and sympathetic nervous system activity in hypertension: a literature review comparing amlodipine and nifedipine GITS

Calcium-channel blockers (CCBs) constitute a diverse group of compounds but are often referred to as a single homogeneous class of drug and the clinical responses indiscriminately summarized. Even within the dihydropyridine subgroup, there are significant differences in formulations, pharmacokinetics, durations of action and their effects on blood pressure, heart rate, end organs and the sympathetic nervous system. Amlodipine and nifedipine in the gastrointestinal therapeutic system (GITS) formulation are the most studied of the once-daily CCBs. Amlodipine has an inherently long pharmacokinetic half-life, whereas, in contrast, nifedipine has an inherently short half-life but in the GITS formulation the sophisticated delivery system allows for once-daily dosing. This article is derived from a systematic review of the published literature in hypertensive patients. The following search terms in three main databases (MEDLINE, Embase, Science Citation Index) from 1990 to 2011 were utilized: amlodipine, nifedipine, sympathetic nervous system, sympathetic response, sympathetic nerve activity, noradrenaline, norepinephrine and heart rate. More than 1500 articles were then screened to derive the relevant analysis. As markers of sympathetic nervous system activation, studies of plasma norepinephrine concentrations, power spectral analysis, muscle sympathetic nerve activity and norepinephrine spillover were reviewed. Overall, each drug lowered blood pressure in hypertensive patients in association with only small changes in heart rate (i.e. <1 beat/min). Plasma norepinephrine concentrations, as the most widely reported marker of sympathetic nervous system activity, showed greater increases in patients treated with amlodipine than with nifedipine GITS. The evidence indicates that both these once-daily dihydropyridine CCBs lower blood pressure effectively with minimal effects on heart rate. There are small differences between the drugs in the extent to which each activates the sympathetic nervous system with an overall non-significant trend in favour of nifedipine GITS.

Discrepant regulation of QT (QTc) interval duration by calcium channel blockade and angiotensin converting enzyme inhibition in experimental hypertension

Antihypertensive treatment may reduce prolonged QT duration in hypertension. Generally, the reductions of blood pressure and/or of cardiac mass are believed to be the responsible factors. However, drugs are not equivalent in QT modulation despite similar antihypertensive and antihypertrophic action. We investigated the effect of a calcium channel blocker, lacidipine and an angiotensin-converting enzyme inhibitor, enalapril on QT duration in rats. Normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were treated with lacidipine (at the dose of 1.5 mg/kg per day for WKY and 3 mg/kg per day for SHR) or enalapril (5 mg/kg per day for WKY and 10 mg/kg per day for SHR) during 8 weeks. Tail-cuff systolic blood pressure (sBP), left ventricular weight (LVW), vascular function of isolated aorta and mesenteric artery and duration of QT (and QTc) interval on Frank electrocardiograms were evaluated. As expected, untreated SHR showed elevated sBP, impaired vascular reactivity, increased LVW and prolonged QT when compared with WKY (p < 0.05). After treatment, both agents markedly improved vascular reactivity and reduced sBP in SHR (p < 0.05). Additionally, enalapril reduced LVW in both hypertensive (by 17%; p < 0.05) and normotensive rats (by 13%; p < 0.05) and, consequently, corrected QT duration in SHR. Interestingly, lacidipine also reduced LVW in SHR (by 9%; p < 0.05), but without influence on prolonged QT. Moreover, lacidipine had no effect on LVW in WKYs but prolonged their QT interval (by 10%; p < 0.05). In conclusion, lacidipine did not reverse a progressive prolongation of QT in SHR, despite sBP lowering and LVW reduction. Thus, the lowering of blood pressure and/or reduction of LVW are not sufficient per se to normalize ventricular repolarization in hypertensive cardiac disease. More likely, modulation of QT prolongation by antihypertensive drugs is a function of their complex action on blood pressure, vascular function, cardiac mass and on reflex neurohumoral activation.

Systematic review of methods used in meta-analyses where a primary outcome is an adverse or unintended event

BACKGROUND

Adverse consequences of medical interventions are a source of concern, but clinical trials may lack power to detect elevated rates of such events, while observational studies have inherent limitations. Meta-analysis allows the combination of individual studies, which can increase power and provide stronger evidence relating to adverse events. However, meta-analysis of adverse events has associated methodological challenges. The aim of this study was to systematically identify and review the methodology used in meta-analyses where a primary outcome is an adverse or unintended event, following a therapeutic intervention.

METHODS

Using a collection of reviews identified previously, 166 references including a meta-analysis were selected for review. At least one of the primary outcomes in each review was an adverse or unintended event. The nature of the intervention, source of funding, number of individual meta-analyses performed, number of primary studies included in the review, and use of meta-analytic methods were all recorded. Specific areas of interest relating to the methods used included the choice of outcome metric, methods of dealing with sparse events, heterogeneity, publication bias and use of individual patient data.

RESULTS

The 166 included reviews were published between 1994 and 2006. Interventions included drugs and surgery among other interventions. Many of the references being reviewed included multiple meta-analyses with 44.6% (74/166) including more than ten. Randomised trials only were included in 42.2% of meta-analyses (70/166), observational studies only in 33.7% (56/166) and a mix of observational studies and trials in 15.7% (26/166). Sparse data, in the form of zero events in one or both arms where the outcome was a count of events, was found in 64 reviews of two-arm studies, of which 41 (64.1%) had zero events in both arms.

CONCLUSIONS

Meta-analyses of adverse events data are common and useful in terms of increasing the power to detect an association with an intervention, especially when the events are infrequent. However, with regard to existing meta-analyses, a wide variety of different methods have been employed, often with no evident rationale for using a particular approach. More specifically, the approach to dealing with zero events varies, and guidelines on this issue would be desirable.

Differential effect of β-blockers for heart rate control in coronary artery disease

BACKGROUND

Resting heart rate is an independent risk factor for cardiovascular disease and is mainly controlled by β-blockers (BBs). BBs are part of the optimal medical treatment for coronary artery disease (CAD), and their benefit correlates with resting heart rate (RHR) reduction.

HYPOTHESIS

RHR is poorly controlled in daily practice among patients with stable cardiovascular disease, and control is only achieved by some BBs.

METHODS

Observational, cross-sectional, and multicenter study of CAD patients recruited nationwide from 20 institutions. Antecedents, risk factors, and treatments were collected. Controlled RHR was considered at <70 bpm.

RESULTS

The mean age of the 2897 patients included was 67.4 years (11.4%), and 75.9% were males. Patients treated with a BB (56.5%) had a lower mean age and comorbidities. The mean RHR was 69.6 bpm (12.6). A significantly lower RHR was observed in patients treated with a BB compared to the rest (67.2 vs 73.0 bpm; P<0.01), and no difference was observed in patients treated with a calciumchannel blocker (CCB). The analysis by individual agents identified that only patients treated with atenolol, bisoprolol, and metoprolol had significantly lower RHR than those not receiving a BB. No differences were observed in mean doses of each agent according to RHR control, except for verapamil. BB treatment was independently associated with RHR control (odds ratio [OR]: 2.42, 95% CI: 2.05-2.87; P<0.01), and no association was found for nondihydropyridine CCBs (OR: 0.99, 95% CI: 0.96-1.02; P = 0.38). Bisoprolol (OR: 1.56, 95% CI: 1.38-1.78; P<0.01), atenolol (OR: 2.01, 95% CI: 1.57-3.49; P<0.01), and metoprolol (OR: 1.29, 95% CI: 1.04-1618; P = 0.04) were independently associated with RHR control.

CONCLUSIONS

RHR is poorly controlled in CAD patients, and although BBs are the most efficient therapy, in daily clinical practice RHR <70 bpm is only independently associated with atenolol, bisoprolol, or metoprolol.

The significance of amlodipine on autonomic nervous system adjustment (ANSA method): a new approach in the treatment of hypertension

INTRODUCTION

Cardiovascular autonomic modulation is altered in patients with essential hypertension.

OBJECTIVE

To evaluate acute and long-term effects of amlodipine on cardiovascular autonomic function and haemodynamic status in patients with mild essential hypertension.

METHODS

Ninety patients (43 male, mean age 52.12 +/- 10.7) years with mild hypertension were tested before, 30 minutes after the first 5 mg oral dose of amlodipine and three weeks after monotherapy with amlodipine. A comprehensive study protocol was done including finger blood pressure variability (BPV) and heart rate variability (HRV) beat-to-beat analysis with impedance cardiography, ECG with software short-term HRV and nonlinear analysis, 24-hour Holter ECG monitoring with QT and HRV analysis, 24-hour blood pressure (BP) monitoring with systolic and diastolic BPV analysis, cardiovascular autonomic reflex tests, cold pressure test, mental stress test. The patients were also divided into sympathetic and parasympathetic groups, depending on predominance in short time spectral analysis of sympathovagal balance according to low frequency and high frequency values.

RESULTS

We confirmed a significant systolic and diastolic BP reduction, and a reduction of pulse pressure during day, night and early morning hours. The reduction of supraventricular and ventricular ectopic beats during the night was also achieved with therapy, but without statistical significance. The increment of sympathetic activity in early phase of amlodipine therapy was without statistical significance and persistence of sympathetic predominance after a few weeks of therapy detected based on the results of short-term spectral HRV analysis. All time domain parameters of long-term HRV analysis were decreased and low frequency amongst spectral parameters. Amlodipne reduced baroreflex sensitivity after three weeks of therapy, but increased it immediately after the administration of the first dose.

CONCLUSION

The results of the study showed that amlodipine affected autonomic modulation as a shift to sympathetic hyperactivity, but without statistical significance. In the selected group of patients with vagal predominance in sympathovagal balance, amlodipine increased sympathetic and decreases vagal activity. Therefore we conclude that amlodipine mostly exerts impact on autonomic function modulation in patients with vagal predominance in resting state.

Azelnidipine, a long-acting calcium channel blocker, could control hypertension without decreasing cerebral blood flow in post-ischemic stroke patients. A 123I-IMP SPECT follow-up study

Azelnidipine, a long-acting calcium channel blocker, is highly lipid soluble and selective for the vascular wall, and is expected to have an increasing effect on cerebral blood flow (CBF). The aim of this study is to investigate its safety and efficacy in stroke patients in the chronic stage as far as CBF is concerned using N-isopropyl-p-(123)I-iodo amphetamine ((123)I-IMP) single-photon emission computed tomography (SPECT). The patients were orally administered 8 or 16 mg of azelnidipine. Regional CBF was evaluated by (123)I-IMP SPECT using three-dimensional stereotactic region-of-interest (ROI) template (3D-SRT), a technique using anatomical standardization and ROI template consisting of 636 ROIs for the whole brain. Mean hemispheric CBF was defined as the mean value of the corpus callosum, and the precentral, central, parietal, angular and temporal gyri. Mean hemispheric and regional CBF after 1, 3 and 6 months were analyzed using a one-way repeated-measures analysis of variance. Ten post-ischemic stroke patients with hypertension were enrolled between October 2005 and October 2007, and all of them were well controlled with normal blood pressure (before: 172.3+/-16.6/88.4+/-14.0 mm Hg; 6 months: 128.7+/-15.9/70.9+/-10.1 mm Hg). No vascular events were observed during the study period. The mean hemispheric CBF was maintained during the study period (before: 46.0+/-9.7 ml per 100 g per min; 6 months: 49.3+/-11.1 ml per 100 g per min). The regional CBF was also maintained. In the chronic stage of ischemic stroke, azelnidipine could safely decrease systemic blood pressure without decreasing CBF.

The effect of angiotensin II on the proliferation of human gingival fibroblasts

Angiotensin not only raises blood pressure and modifies body fluids and electrolytes but also induces differentiation and proliferation of fibroblasts in the circulatory system in order to repair damage. The purpose of the present study was to observe the influence of the addition of angiotensin II (AngII) or nifedipine (NIF) alone or both sequentially on proliferative activity, the intracellular Ca(2+) concentration ([Ca(2+)]i), and the inositol-1,4,5-triphosphate (IP3) level in cultivated human gingival fibroblasts. Addition of 10(-8)-10(-4) M NIF or 10(-5)-10(-4) M AngII alone increased the proliferation of cultivated gingival fibroblasts, and the interaction of NIF and AngII suppressed proliferation. Addition of AngII alone increased [Ca(2+)]i, with a peak 60 s afterward and a return to a level slightly higher than the pretreatment level at 120 s. Addition of both AngII and NIF did not increase [Ca(2+)]i as much as the addition of AngII alone. When Ca(2+) was absent from the extracellular environment, the AngII-induced increase in [Ca(2+)]i was suppressed. AngII increased the concentration of IP(3), with a peak at 120 s after its addition. From these results we concluded that AngII increased the proliferation of gingival fibroblasts by causing an influx of Ca(2+), which increased [Ca(2+)]i.

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.

Cardiovascular drugs as antidiabetic agents: evidence for the prevention of type 2 diabetes

Given the long-term health consequences and increasing incidence of type 2 diabetes, there is great interest to potentially prevent or delay its onset. Primary prevention studies have demonstrated that intensive exercise and weight reduction, and to a lesser extent certain antidiabetic agents, can reduce new onset diabetes in at-risk individuals. Results from post hoc analyses and secondary end-point outcomes of large randomized controlled trials of cardiovascular drugs suggest that these may also have beneficial effects, reducing the incidence of new onset diabetes in addition to their proven cardiovascular benefits. Multiple meta-analyses confirm that drugs primarily acting on the renin-angiotensin system (RAS) reduce the incidence of diabetes in the populations studied, perhaps via improved insulin sensitivity and/or effects on pancreatic beta cells. However, results from the recent Diabetes REduction Approaches with Medication study specifically failed to show a significant reduction in the incidence of diabetes with ramipril in individuals with abnormal glucose tolerance at baseline. There is only limited evidence that statins improve glucose tolerance, and although beta-blockers tend to have detrimental effects on glucose tolerance, newer agents with vasodilatory properties may confer benefits. With current guidelines, the use of cardiovascular drugs modifying the RAS will increase in at-risk individuals, but at present, they cannot be recommended to prevent diabetes.

Efficacy and safety of two treatment combinations of hypertension in very elderly patients

The study compared valsartan/amlodipine combination with irbesartan/hydrochlorothiazide (HCTZ) combination in very elderly hypertensives. After a 4-week placebo period, 94 hypertensives, aged 75-89 years were randomized to valsartan 160mg/amlodipine 5mg or irbesartan 300mg/HCTZ 12.5mg for 24 weeks according to a prospective, parallel group study. After 4 weeks amlodipine or HCTZ was doubled in non-responders. Patients were checked every 4 weeks. At each visit clinical sitting, lying and standing blood pressure (BP), systolic BP (SBP) and diastolic BP (DBP) were evaluated, and an electrocardiogram was performed. At the end of the placebo period and of the treatment period a non-invasive 24-h ambulatory BP monitoring (ABPM) was performed and electrolytes and uric acid were evaluated. Both combinations significantly reduced ambulatory BP. In the valsartan/amlodipine group the mean reduction (-29.9/-15.6 for 24h, -28.6/-14.5mmHg for day-time and -26.2/-17.4mmHg for night-time SBP/DBP) was similar to that of the irbesartan/HCTZ group (-29.6/-15.4 for 24h, -29.3/-14.9mmHg for day-time and -25.4/-16.9mmHg for night-time SBP/DBP). Both combinations significantly reduced clinical sitting and lying BP values with no difference between treatments. BP changes from lying to standing position were significantly greater in the irbesartan/HCTZ group (-17.2/-9.1mmHg) than in the valsartan/amlodipine group (-10.1/-1.9mmHg, p<0.05 for SBP and p<0.01 for DBP vs. irbesartan/HCTZ). Potassium significantly decreased and uric acid significantly increased (-0.4mmol/l, p<0.05 and +0.5mg/dl, p<0.05 vs. baseline, respectively) only in the irbesartan/HCTZ group. In conclusion, both combinations were similarly effective in reducing ambulatory and clinical BP in very elderly hypertensives. However, valsartan/amlodipine offered some advantages in terms of less pronounced BP orthostatic changes and absence of metabolic adverse effects.

Review: Concomitant calcium entry blockade and inhibition of the renin-angiotensin system: a rational and effective means for treating hypertension

Pharmacological treatment of hypertension is effective in preventing cardiovascular and renal complications. Calcium antagonists (CAs) and blockers of the renin-angiotensin system [angiotensin-converting enzyme (ACE) inhibitors and angiotensin II antagonists (ARBs)] are widely used today to initiate antihypertensive treatment but, when given as monotherapy, do not suffice in most patients to normalise blood pressure (BP). Combining a CA and either an ACE-inhibitor or an ARB considerably increases the antihypertensive efficacy, but not at the expense of a deterioration of tolerability. Several fixed-dose combinations are available (CA + ACE-inhibitors: amlodipine + benazepril, felodipine + ramipril, verapamil + trandolapril; CA + ARB: amlodipine + valsartan). They are expected not only to improve BP control, but also to facilitate long-term adherence with ON antihypertensive therapy, thereby providing renal damage caused by high BP. maximal protection against the cardiovascular and renal damage caused by high BP.

Does a change in angiotensin II formation caused by antihypertensive drugs affect the risk of stroke?

BACKGROUND

Stroke prevention by antihypertensive therapy is believed to be related to the fall in blood pressure (BP). Experimental data have documented that activation of non-AT1 receptors of angiotensin II may exert anti-ischaemic mechanisms in the brain. The present meta-analysis of various randomized clinical trials attempts to relate stroke risk to angiotensin II formation during antihypertensive therapy.

METHODS

Primary and secondary stroke prevention was examined in 26 prospective, randomized clinical trials including 206,632 patients without heart failure, in whom a total of 7,108 strokes occurred. The trials were selected because a difference in angiotensin II generation was expected between the two treatment arms on the basis of the drugs' pharmacodynamic effects, and allowed 36 evaluations of the relative risk of stroke.

FINDINGS

In placebo-controlled trials, stroke risk was significantly higher with angiotensin II-decreasing than increasing drugs, but systolic BP decreased less in the former. Compared with an active therapy having a neutral effect on angiotensin II formation, stroke risk was also higher with angiotensin-decreasing drugs than with angiotensin-increasing drugs, whereas BP decrease was comparable with both drug classes. When angiotensin II-decreasing drugs were directly compared with angiotensin II-increasing drugs in the same trials, stroke risk was significantly increased. On-treatment systolic BP was minimally and significantly higher with angiotensin II-decreasing drugs, but not large enough to explain the excess in stroke risk.

CONCLUSION

Within the limitations of the methodology, our meta-analysis supports the hypothesis that angiotensin II-decreasing drugs are less stroke protective than angiotensin II-increasing drugs, although this difference is not entirely explained by their smaller BP-lowering effect.

Treatment of hypertension in patients with diabetes mellitus

Antihypertensive treatment in diabetes mellitus, especially in diabetics known to have cardiac autonomic neuropathy, may have to consider the status of the autonomic nervous system. In diabetic subjects with cardiac autonomic neuropathy, vagal activity during the night is often reduced. The reduction results in relative or absolute sympathetic activation, which could increase cardiovascular risk. Pathophysiological and clinical data suggests that antihypertensive treatment should reduce rather than induce sympathetic activity in this setting. Beta blocking agents, ACE inhibitors, calcium antagonists of verapamil or diltiazem type and selective imidazoline receptor agonists reduce sympathetic activity and, therefore, may have a beneficial effect in diabetic patients with disturbed sympathovagal balance.

Calcium antagonist verapamil prevented pulmonary arterial hypertension in broilers with ascites by arresting pulmonary vascular remodeling

Calcium signaling has been reported to be involved in the pathogenesis of hypertension. Verapamil, one of the calcium antagonists, is used to characterize the role of calcium signaling in the development of pulmonary arterial hypertension syndrome in broilers. The suppression effect of verapamil on pulmonary arterial hypertension and pulmonary vascular remodeling was examined in broilers, from the age of 16 days to 43 days. Our results showed that oral administration of lower dose of verapamil (5 mg/kg body weight every 12 h) prevented the mean pulmonary arterial pressure, the ascites heart index and the erythrocyte packed cell volume of birds at low temperature from increasing, the heart rate from decreasing, and pulmonary arteriole median from thickening, and no pulmonary arteriole remodeling in broilers treated with the two doses of verapamil at low temperature was observed. Our results indicated that calcium signaling was involved in the development of broilers' pulmonary arterial hypertension, which leads to the development of ascites, and we suggest that verapamil may be used as a preventive agent to reduce the occurrence and development of pulmonary arterial hypertension in broilers.

Long-term calcium antagonist treatment of human hypertension with mibefradil or amlodipine increases sympathetic nerve activity

OBJECTIVES

Calcium antagonists are vasodilating drugs, which may cause reflex activation of the sympathetic nervous system with potentially untoward effects. We studied the effects of long-term treatment with amlodipine, a long-acting dihydropyridine-type calcium antagonist, and mibefradil, a phenylalkylamine-type calcium antagonist, on sympathetic nerve activity.

METHODS

Fourteen patients with primary hypertension participated in a double-blind, cross-over study comparing the effects of 6 weeks of treatment with mibefradil 100 mg daily and amlodipine 10 mg daily. Heart rate, direct arterial blood pressure and cardiac output by echocardiography were registered. Global sympathetic activity was estimated using a [3H]noradrenaline isotope dilution method with arterial and venous sampling; cardiac sympathetic activity was assessed indirectly by heart rate variability and tissue velocity echocardiography.

RESULTS

Both drugs lowered mean arterial pressure; the decrease was more pronounced with mibefradil (from 118 +/- 3 to 99 +/- 2 mmHg, compared to 118 +/- 3 to 104 +/- 2 mmHg for amlodipine, P < 0.01 between drugs). Mibefradil decreased heart rate (66 +/- 2 to 57 +/- 2 bpm), whereas amlodipine caused a slight increase (66 +/- 2 to 70 +/- 2 bpm; P < 0.001 between drugs) and tended to increase cardiac output. Noradrenaline spillover increased similarly with the two drugs, from 3.44 +/- 0.27 to 5.20 +/- 0.48 nmol/min per m2(P < 0.01) during mibefradil and to 5.72 +/- 0.49 nmol/min per m2 (P < 0.001) during amlodipine. There were minor effects on cardiac sympatho-vagal balance, but systolic and diastolic myocardial velocities were increased similarly by both drugs.

CONCLUSIONS

Mibefradil and amlodipine treatment increase global sympathetic nerve activity similarly during long-term treatment, despite opposite effects on heart rate. Increases in myocardial velocities suggest concomitant cardiac sympathetic activation.

Effects of benidipine, a long-lasting dihydropyridine-Ca2+ channel blocker, on cerebral blood flow autoregulation in spontaneously hypertensive rats

Chronic hypertension shifts cerebral blood flow (CBF) autoregulation towards higher blood pressure. We examined whether or not benidipine, a long-lasting dihydropyridine calcium channel blocker (CCB), improves the CBF autoregulation in spontaneously hypertensive rats (SHRs). CBF was analyzed by laser-Doppler flowmetry during stepwise hypotension by controlled bleeding. The lower limit of CBF autoregulation was calculated as the mean arterial blood pressure at which CBF decreased by 10% of the baseline. Mean arterial blood pressure and cerebral vascular resistance in SHRs were higher than those in normotensive Wistar rats. Oral administration of benidipine (3 mg/kg) for 8 d lowered the mean arterial blood pressure and cerebral vascular resistance, which were equivalent to the effects of amlodipine (3 mg/kg), another CCB, or candesartan (1 mg/kg), an Angiotensin II type-1 receptor blocker. The lower limit of CBF autoregulation in SHRs (142+/-4 mmHg) was significantly shifted to a higher-pressure level compared with Wistar rats (59+/-2 mmHg). The lower limit of CBF autoregulation was significantly lower in the benidipine-treated group (91+/-4 mmHg) than that in the control SHRs, and similar to that of the amlodipine group (97+/-6 mmHg). Benidipine reduced the lower limit of CBF autoregulation more effectively than candesartan (109+/-4 mmHg). In conclusion, benidipine shifted the limit of CBF autoregulation towards lower blood pressure in SHRs under hypotensive conditions by hemorrhage. These results suggest that benidipine may be useful for the treatment of hypertensive patients with the elderly or cerebrovascular disorders, in whom autoregulation of CBF is impaired.

Azelnidipine Attenuates Cardiovascular and Sympathetic Responses to Air-Jet Stress in Genetically Hypertensive Rats

Azelnidipine is a new dihydropyridine calcium channel blocker that causes minimal stimulation of the sympathetic nervous system despite its significant depressor effect. In the present study, we examined the effects of oral or intravenous administration of azelnidipine on cardiovascular and renal sympathetic nerve activity (RSNA) responses to air-jet stress in conscious, unrestrained stroke-prone spontaneously hypertensive rats. Oral administration of high-dose azelnidipine (10 mg/kg per day) or nicardipine (150 mg/kg per day) for 10 days caused a significant and comparable decrease in blood pressure, but low-dose azelnidipine (3 mg/kg per day) did not. Air-jet stress increased mean arterial pressure (MAP), heart rate (HR) and RSNA. High-dose azelnidipine significantly attenuated the increases in MAP, HR and RSNA in response to air-jet stress while nicardipine did not. Low-dose azelnidipine significantly attenuated the pressor response with a trend of decrease in RSNA. Intravenous injection of azelnidipine induced a slowly developing depressor effect. To obtain a similar time course of decrease in MAP by azelnidipine, nicardipine was continuously infused at adjusted doses. Both drugs increased HR and RSNA significantly, while the change in RSNA was smaller in the azelnidipine group. In addition, intravenous administration of azelnidipine attenuated the responses of MAP, HR, and RSNA to air-jet stress; by comparison, the inhibitory actions of nicardipine were weak. In conclusion, oral or intravenous administration of azelnidipine inhibited cardiovascular and sympathetic responses to air-jet stress. This action of azelnidipine may be mediated at least in part by the inhibition of the sympathetic nervous system.

Modified-release nifedipine: a review of the use of modified-release formulations in the treatment of hypertension and angina pectoris

Nifedipine is a dihydropyridine calcium channel antagonist with predominantly vasodilatory activity. Modified-release formulations of nifedipine are effective antihypertensive and antianginal therapies and are generally well tolerated. Among the available formulations, those that produce a gradual increase in plasma nifedipine concentration, which is then sustained over a 24-hour period, are preferred, as they cause a gradual onset of vasodilatation and avoid baroreflex sympathetic activation (for example, nifedipine gastrointestinal therapeutic system [GITS] and a Japanese controlled-release formulation). Modified-release nifedipine had beneficial effects on a number of markers of vascular function, and nifedipine GITS reduced the need for coronary procedures in patients with coronary artery disease. In patients with hypertension, nifedipine GITS and nifedipine retard had beneficial effects on the overall incidence of major cardiovascular events, as did nifedipine retard in patients with concurrent hypertension and coronary artery disease.

Sympatho-excitatory responses to once-daily dihydropyridines in young versus older hypertensive patients: amlodipine versus felodipine extended release

BACKGROUND

Once-daily dihydropyridines exert both indirect sympatho-excitatory and direct central sympatho-inhibitory effects. Age may affect this balance by influencing blood pressure (BP) or renin responses.

METHODS

We evaluated BP, sympathetic and cardiac responses after the first dose and after 8 weeks of treatment with placebo, amlodipine 5 mg/day or felodipine extended release (ER) 5 mg/day in 29 young (22-50 years) versus 37 older (60-77 years) hypertensive patients, using a double-blind, parallel group design.

RESULTS

In the young group, neither dihydropyridine dose decreased BP after the first dose and both caused decreases by 5-10 mmHg after chronic treatment. In the older group, felodipine ER decreased BP rapidly and amlodipine more gradually, and after chronic treatment, systolic BP decreased by 20-25 mmHg. Felodipine ER increased the heart rate by 5-10 bpm after the first dose in both age groups and caused persistent increases in the cardiac index (by 0.2 l/min per square metre) and the ejection fraction only in the older group. Amlodipine did not affect cardiac function in the young, and with chronic dosing decreased the heart rate by 3-5 bpm and the cardiac index by 0.2 l/min per square metre in the older group. In the young hypertensive patients, both dihydropyridines increased plasma norepinephrine (NE) after chronic dosing, with little effect after the first dose. In contrast, in the older group felodipine ER increased plasma NE after the first dose but not with chronic dosing, whereas amlodipine had no effect after the first dose, and after chronic dosing tended to decrease plasma NE.

CONCLUSION

We conclude that age is a major determinant not only of the BP but also of the cardiac and sympathetic responses to once-daily dihydropyridines.

Pharmacological, Pharmacokinetic, and Clinical Properties of Benidipine Hydrochloride, a Novel, Long-Acting Calcium Channel Blocker

Benidipine is a dihydropyridine-derived calcium channel blocker developed in Japan, with several unique mechanisms of action, that is, triple calcium channels (L, N, and T) blocking action with a membrane approach. Benidipine has relatively high vascular selectivity and is expected to show protective effects on vascular endothelial cells. Renal protective effects of benidipine also have been shown in several basic and clinical studies. Moreover, anti-oxidative action and enhancing nitric oxide production have been noted with this drug, following its cardio-protective effects in patients with ischemic heart diseases. In fact, benidipine exerted a better prognostic effect than other calcium channel blockers in the therapy for patients with vasospastic angina. In addition, benidipine showed reliable antihypertensive, renoprotective effects if used in combination with angiotensin II type 1 receptor blockers (ARBs) when adequate anti-hypertensive effects are not achieved by ARBs alone, indicating that benidipine is an useful calcium channel blocker in combination therapy for hypertension. Benidipine was launched on the Japanese market 14 years ago, but few severe side effects have been reported, suggesting that this is a drug with established safety and long-acting pharmacological effects.

Fixed combination of manidipine and delapril in the treatment of mild to moderate essential hypertension: evaluation by 24-hour ambulatory blood pressure monitoring

This present study assessed the antihypertensive efficacy of the fixed combination of manidipine and delapril by ambulatory blood pressure monitoring in patients with hypertension inadequately controlled by monotherapy with either component. After a 2-week placebo period, 55 mild to moderate hypertensive patients were randomized to manidipine 20 mg o.d. or delapril 30 mg b.i.d. for 4 weeks. After this period, 30 patients, aged 30-76 years (18 males and 12 females) whose diastolic blood pressure was not adequately controlled (> or = 90 mmHg) by monotherapy were treated with the fixed combination of manidipine 10 mg plus delapril 30 mg o.d. for 8 weeks. A 24-h ambulatory blood pressure monitoring recording was performed at the end of the placebo washout, of the monotherapy and of the combination therapy. Blood pressure control over the 24 h was quantified by the trough-to-peak ratio and the smoothness index. As compared to placebo, the fixed combination of manidipine and delapril produced a statistically significant (p<0.01) decrease in sitting clinic (18 +/- 9/14 +/- 5 mmHg) and 24-h blood pressure (12 +/- 7/10 +/- 5 mmHg) without affecting heart rate. This reduction was greater than that observed with single components. At the end of the 8-week combination treatment period, the rate of normalilized patients was 73%. Treatment with the fixed combination was associated with a positively high smoothness index (1.2 +/- 0.7/13.8 +/- 0.8) and with a relatively good trough-to-peak ratio (0.46/0.60). The combination of manidipine and delapril produced significant and smooth reductions in blood pressure values, which persisted over the 24-h dosing interval. These results support the use of fixed manidipine-delapril combination in the treatment of mild to moderate hypertensive patients inadequately controlled by monotherapy.

Ventricular arrhythmia following short-acting nifedipine administration

Short-acting nifedipine is still advocated for use in children with severe hypertension, but is no longer recommended for use in adults because of adverse effects from rapid blood pressure reduction. A 19 year-old adolescent with symptomatic, severe hypertension (blood pressure 180/120) received 10 mg of short-acting nifedipine sublingually for blood pressure reduction. Within minutes after the dose, the patient complained of palpitations. Tachycardia (heart rate 100 beats per minute) and bigeminy were noted on the cardiac monitor. The bigeminy resolved but premature ventricular contractions were noted for the duration of her hospital stay. We hypothesize that reflex sympathetic activation following an abrupt drop in blood pressure may cause arrhythmias because of elevated catecholamine levels. Given this, it may be more appropriate to treat severe hypertension in children with intravenous antihypertensive agents that can be titrated to produce controlled reductions in blood pressure.

Clinic blood pressure responses to two amlodipine salt formulations, adipate and besylate, in adult Korean patients with mild to moderate hypertension: A multicenter, randomized, double-blind, parallel-group, 8-week comparison

BACKGROUND

The commercially available formulation of amlodipine is conjugated with besylate salt to increase water solubility. Recently, a new amlodipine salt formulation has been developed in which the free base of amlodipine is conjugated with a chemically different salt, adipate.

OBJECTIVE

The goal of this study was to compare the antihypertensive effect and tolerability of amlodipine adipate with those of amlodipine besylate in patients with mild to moderate hypertension.

METHODS

This was a multicenter, randomized, doubleblind, parallel-group study in which patients received 8 weeks of treatment with either amlodipine adipate or amlodipine besylate. The primary efficacy variable was noninferiority of the difference in mean changes from baseline in trough diastolic blood pressure (DBP) after 8 weeks of treatment. Secondary efficacy variables included mean changes in DBP, systolic blood pressure (SBP), and response rate (defined as the proportion of patients whose DBP was <90 mm Hg or whose DBP had decreased from baseline by > or =10 mm Hg). The incidence of adverse events (AEs) was also assessed.

RESULTS

Two hundred eleven patients were randomly assigned to receive amlodipine adipate (n = 106) or amlodipine besylate (n = 105). Study patients were primarily female (54.5%), with a mean (SD) age of 52.2 (9.6) years and a mean body weight of 67.1 (10.2) kg; there were no between-group differences in demographic profiles. After 4 weeks of randomized treatment, 58 (27.5%) patients (29 [27.4%] amlodipine adipate, 29 [27.6%] amlodipine besylate) had not achieved a mean DBP <90 mm Hg, and their dose was doubled. Mean DBP changes at 8 weeks were -15.2 (7.3) mm Hg in the amlodipine adipate group and -14.2 (7.4) mm Hg in the amlodipine besylate group (P = NS). Because the 95% CI for the difference in mean DBP changes between groups (-0.53 to 2.55) was within the prespecified lower limit (-4 mm Hg), amlodipine adipate was considered noninferior to amlodipine besylate. Mean SBP changes were -24.9 (12.1) mm Hg in the amlodipine adipate group and -22.0 (14.7) mm Hg in the amlodipine besylate group (P = NS). The response rates were 92.0% for amlodipine adipate and 95.4% for amlodipine besylate (P = NS). The overall incidence of clinical AEs was 20.8% in the amlodipine adipate group and 25.7% in the amlodipine besylate group (P = NS). Drug-related clinical AEs occurred in 5.7% and 12.4% of patients in the respective treatment groups (P = NS). Serum uric acid levels decreased significantly from base-line in both groups (P < 0.001).

CONCLUSIONS

Eight weeks of treatment with amlodipine adipate produced significant reductions from baseline in blood pressure in these patients with mild to moderate hypertension. The efficacy of amlodipine adipate was not inferior to that of amlodipine besylate. Tolerability was comparable between the 2 treatment groups.