Comparative efficacy and tolerability of two long-acting calcium antagonists, mibefradil and amlodipine, in essential hypertension. Mibefradil Hypertension Study Group

Efficacy and safety of the dual L- and T-type calcium channel blocker, ACT-280778: a proof-of-concept study in patients with mild-to-moderate essential hypertension

ACT-280778 is an oral, non-dihydropyridine, dual L-/T-type calcium channel blocker. This phase 2a, double-blind, randomized, placebo- and active-controlled study investigated the efficacy and safety of 10 mg ACT-280778. Patients with mild-to-moderate essential hypertension received once-daily placebo (n=53), ACT-280778 10 mg (n=52) or amlodipine 10 mg (n=54) for 4 weeks. The primary end point was the change from baseline to week 4 in placebo-adjusted mean trough sitting diastolic blood pressure (SiDBP) with ACT-280778. Tolerability was assessed by recording treatment-emergent adverse events (TEAEs). Baseline clinical characteristics were similar across groups. No significant difference was observed at week 4 in mean trough SiDBP between placebo (-9.9 (95% confidence limit (CL) -12.7, -7.0) mm Hg) and ACT-280778 (-9.5 (-12.4, -6.5) mm Hg; P=0.86); amlodipine reduced mean trough SiDBP by -16.8 (-19.0, -14.5) mm Hg, confirming assay validity. Change in mean PR interval at week 4 (pre-dose) differed between placebo (-1.0 (95% CL -4.4, 2.3) ms) and ACT-280778 (6.5 (3.5, 9.6) ms); amlodipine did not increase PR interval (1.1 (-1.6, 3.9) ms).Treatment-emergent adverse events (TEAE) frequency was 32.1% (placebo), 32.7% (ACT-280778) and 33.3% (amlodipine). The most common TEAEs were headache, peripheral edema, hypertension and second-degree atrioventricular block. ACT-280778 (10 mg) did not lower blood pressure in mild-to-moderate hypertension.

Excellent tolerance to cilnidipine in hypertensives with amlodipine - induced edema

Background:

Ankle edema is a common adverse effect of amlodipine, an L-type calcium channel blocker (CCB). Cilnidipine is a newer L/N-type CCB, approved for treatment of essential hypertension.

Aim:

This study was designed to determine whether cilnidipine can produce resolution of amlodipine-induced edema while maintaining adequate control of hypertension.

Materials and Methods:

A prospective study was performed on 27 patients with essential hypertension with amlodipine-induced edema. Concomitant nephropathy, cardiac failure, hepatic cirrhosis, or other causes of edema, and secondary hypertension were excluded by appropriate tests. Amlodipine therapy was substituted in all the cases with an efficacy-equivalent dose of cilnidipine. Clinical assessment of ankle edema and measurement of bilateral ankle circumference, body weight, blood pressure, and pulse rate were performed at onset of the study and after 4 weeks of cilnidipine therapy.

Results:

At completion of the study, edema had resolved in all the patients. There was a significant decrease in bilateral ankle circumference and body weight (P < 0.001). There was no significant change in mean arterial blood pressure and pulse rate.

Conclusions:

Therapy with cilnidipine resulted in complete resolution of amlodipine-induced edema in all the cases without significant worsening of hypertension or tachycardia. Cilnidipine is an acceptable alternative antihypertensive for patients with amlodipine-induced edema.

Peripheral edema associated with calcium channel blockers: incidence and withdrawal rate--a meta-analysis of randomized trials

OBJECTIVE

Peripheral edema is considered to be a common and annoying adverse effect of calcium channel blockers (CCBs). It has been thought to occur secondary to arteriolar dilatation causing intracapillary hypertension and fluid extravasation. We aimed to evaluate the incidence and withdrawal rate of peripheral edema with CCBs.

METHODS

A systematic search was made in PubMed, EMBASE and CENTRAL from 1980 to January 2011 for randomized clinical trials reporting peripheral edema with CCBs in patients with hypertension. Trials enrolling at least 100 patients in the CCB arm and lasting at least 4 weeks were included in the analysis. Both the incidence and withdrawal rate due to edema were pooled by weighing each trial by the inverse of the variance. Head-to-head comparison was done to evaluate the risk of edema between newer lipophilic dihydropyridine (DHP) CCBs and older DHPs.

RESULTS

One hundred and six studies with 99 469 participants, mean age 56 ± 6 years, satisfied our inclusion criteria and were included in this analysis. The weighted incidence of peripheral edema was significantly higher in the CCBs group when compared with controls/placebo (10.7 vs. 3.2%, P < 0.0001). Similarly, the withdrawal rate due to edema was higher in patients on CCBs compared with control/placebo (2.1 vs. 0.5%, P < 0.0001). Both the incidence of edema and patient withdrawal rate due to edema increased with the duration of therapy with CCBs reaching 24 and 5%, respectively, after 6 months. The risk of peripheral edema with lipophilic DHPs was 57% lower than with traditional DHPs (relative risk 0.43; 95% confidence interval 0.34-0.53; P < 0.0001). Incidence of peripheral edema in patients on DHPs was 12.3% compared with 3.1% with non-DHPs (P < 0.0001). Edema with high-dose CCBs (defined as more than half the usual maximal dose) was 2.8 times higher than that with low-dose CCBs (16.1 vs. 5.7%, P < 0.0001).

CONCLUSION

The incidence of peripheral edema progressively increased with duration of CCB therapy up to 6 months. Over the long term, more than 5% of patients discontinued CCBs because of this adverse effect. Edema rates were lower with both non-DHPs and lipophilic DHPs.

The T- and L-type calcium channel blocker (CCB) mibefradil attenuates leg edema induced by the L-type CCB nifedipine in the spontaneously hypertensive rat: a novel differentiating assay

Among the L-type calcium channel blockers (CCBs), particularly dihydropyridines like nifedipine [1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinedicarboxylic acid dimethyl ester], a common adverse effect is vasodilatory edema. Newer CCBs, such as the T- and L-type CCB, mibefradil [(1S,2S)-2-[2[[3-(2-benzimidazolylpropyl]methylamino]ethyl]-6-fluoro-1,2,3,4-tetrahydro-1-isopropyl-2-naphthyl methoxyacetate dihydrochloride hydrate], demonstrate antihypertensive efficacy similar to that of their predecessors but seem to have a reduced propensity to cause edema. Using a magnetic resonance imaging (MRI) T(2) mapping technique, we investigated the ability of mibefradil to reduce extracellular water accumulation caused by the L-type CCB, nifedipine, in the hindleg skeletal muscle of the spontaneously hypertensive rat. Mibefradil (10 mg/kg i.v.) and nifedipine (1 mg/kg i.v.) lowered mean arterial blood pressure by 97 +/- 5 and 77 +/- 4 mm Hg, respectively. MRI edema index (expressed as percentage increase of integral T(2) over predrug control) was significantly higher with nifedipine (2606 +/- 86%; p < 0.05) than with mibefradil (981 +/- 171%) measured 30 to 60 min after the start of drug infusion. The hindleg edema caused by nifedipine was dose dependently decreased by coadministration of mibefradil (0, 0.3, or 3 mg/kg). The hindleg edema formation was not due to albumin leakage into the interstitial space based on immunostaining. However, a 4.2-fold increase in the arterial L-/T-type CC mRNA expression ratio was observed compared with the venous L/T ratio as shown by quantitative reverse transcription polymerase chain reaction. These results demonstrate the novel utility of MRI to measure extravascular water after acute exposure to CCBs and indicate that T-type CCB activity may reduce L-type CCB-induced vasodilatory edema in the skeletal muscle vasculature, possibly by a differential effect on arteriole and venule dilatation.

Choice of delta: requirements and reality--results of a systematic review

An essential problem in planning clinical non-inferiority or equivalence studies is the specification of the 'irrelevant difference' (irrelevance margin; delta). This quantifies the amount of non-inferiority or difference, respectively, between a new test therapy and an established standard treatment which is to be considered as tolerable. In the past, most recommendations and guidelines for clinical non-inferiority and equivalence studies contained only general statements and formulations concerning the specification of delta. The current unsatisfactory situation was the reason for performing a systematic review of published clinical non-inferiority and equivalence studies. It was the aim to gain an overview on the irrelevance margins used in such studies, and on reasons for choosing the particular margins. For the sake of comparability, the irrelevance margins were converted into standardized differences and odds ratios. Overall, there were 332 non-inferiority or equivalence trials obtained by means of an extensive literature search. The results of the systematic review show that current requirements on the choice of delta and the reality of recent clinical non-inferiority and equivalence trials differ substantially. In about one half of the trials a difference of 0.5 standard deviations or more was regarded as 'irrelevant' explicitly or implicitly. Estimates of standard-placebo differences formed the basis of the irrelevance margin in less than every tenth trial. Reasons for this very low proportion might be (1) the possibly resulting very small irrelevance margins, and (2) unsolved problems of the requirements themselves. Overall, it seems that a more global definition of 'irrelevance' might be warranted.

Effect of amlodipine on systolic blood pressure

BACKGROUND

Systolic hypertension is the most common form of hypertension, particularly in people aged >60 years. Caused by decreased compliance of large arteries, systolic hypertension is an independent risk factor for cardiovascular disease. Recent studies have demonstrated that it is more important to control systolic blood pressure (SBP) than diastolic blood pressure (DBP).

OBJECTIVE

The objective of this study was to perform a systematic literature review to examine the effectiveness of amlodipine in lowering SBP in a variety of patient subgroups and clinical settings.

METHODS

The literature review methodology included identifying, selecting, appraising, extracting, and synthesizing primary research studies. Following an a priori protocol, published literature was searched from 1980 to 2001 using 3 electronic databases. A manual review of the reference lists of recent review articles and all accepted studies was performed. Parallel-group, randomized, controlled trials that included at least 10 adults with baseline hypertension (SBP>or=140 mm Hg, DBP>or=90 mm Hg, or both), included at least 1 arm randomized to initial treatment with amlodipine monotherapy, had a minimum treatment duration of 8 weeks, and reported baseline and end-point blood pressure were included.

RESULTS

Of 696 citations identified, 85 primary studies met all inclusion criteria. Comparable treatment arms were pooled, and weightd mean SBP was calculated. In the amlodipine monotherapy arms, which included >5000 patients, SBP decreased by a mean of 17.5 mm Hg from baseline. The effect of amlodipine in reducing SBP was greater in elderly patients (age>or=60 years) and patients with author-defined isolated systolic hypertension. The dose was titrated to achieve the target blood pressure in 73 of 89 amlodipine treatment arms, whereas 16 treatment arms reported fixed doses. The median daily dose was 5 mg (range, 1.25-15 mg) in both the fixed-dose and dose-titration groups.

CONCLUSIONS

In this review of the published literature, amlodipine monotherapy was effective in reducing SBP. Antihypertensive agents such as amlodipine warrant consideration for the management of patients with inadequately controlled SBP.

Randomized comparison of T-type versus L-type calcium-channel blockade on exercise duration in stable angina: results of the Posicor Reduction of Ischemia During Exercise (PRIDE) trial

BACKGROUND

Mibefradil is a T-type calcium-channel antagonist and arterial vasodilator with negative chronotropic effects. It is not known if T-type calcium-channel blockade is superior to L-type calcium-channel blockade in patients with stable angina pectoris.

METHODS

A multicenter, randomized, double-blind trial was conducted in patients with documented coronary disease and stable angina to compare a 360 mg dose of diltiazem CD with 100 mg dose of mibefradil. The primary end point was change in time to symptom-limited exercise termination from baseline to 8 weeks. Secondary efficacy parameters included time to onset of persistent ST-segment depression, time to awareness of angina, and change in exercise duration from baseline to 2 and 4 weeks of treatment.

RESULTS

A total of 121 patients were randomized to mibefradil and 113 to diltiazem CD. At 8 weeks, the increase in exercise duration was 24.5 seconds greater in the mibefradil group (P =.017; 95% CI 4.4-44.7 seconds). At 8 weeks, time to development of > or =1 mm ST-segment depression was greater by 45.3 seconds (P =.0025; 95% CI 16.2-74.5) with mibefradil, but time to development of angina was not significantly different.

CONCLUSION

T-type calcium-channel antagonism with mibefradil improved treadmill exercise parameters compared with diltiazem in patients with chronic stable angina. Further investigation and development of antagonists of T-type calcium channels with fewer adverse drug interactions is warranted and may be promising in the management of ischemic heart disease.