Sympathetic activation after two weeks of nifedipine treatment in primary Raynaud's patients and controls

Calcium channel blockers for primary and secondary Raynaud's phenomenon

BACKGROUND

Raynaud's phenomenon is a vasospastic disease characterized by digital pallor, cyanosis, and extremity pain. Primary Raynaud's phenomenon is not associated with underlying disease, but secondary Raynaud's phenomenon is associated with connective tissue disorders such as systemic sclerosis, systemic lupus erythematosus, and mixed connective tissue disease. Calcium channel blockers promote vasodilation and are commonly used when drug treatment for Raynaud's phenomenon is required.

OBJECTIVES

To assess the benefits and harms of calcium channel blockers (CCBs) versus placebo for treatment of individuals with Raynaud's phenomenon with respect to Raynaud's type (primary vs secondary) and type and dose of CCBs.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (May 19, 2017), MEDLINE (1946 to May 19, 2017), Embase (1947 to May 19, 2017), clinicaltrials.gov, and the World Health Organization (WHO) International Clinical Trials Registry Portal. We applied no language restrictions. We also searched bibliographies of retrieved articles and contacted key experts for additional and unpublished data.

SELECTION CRITERIA

All randomized controlled trials (RCTs) comparing calcium channel blockers versus placebo.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed search results and risk of bias and extracted trial data. We used the GRADE approach to assess the quality of evidence.

MAIN RESULTS

This review contains 38 RCTs (33 cross-over RCTs) with an average duration of 7.4 weeks and 982 participants; however, not all trials reported all outcomes of interest. Nine of the identified trials studied patients with primary Raynaud's phenomenon (N = 365), five studied patients with secondary Raynaud's phenomenon (N = 63), and the rest examined a mixture of patients with primary and secondary Raynaud's phenomenon (N = 554). The most frequently encountered risk of bias types were incomplete outcome data and poor reporting of randomization and allocation methods.When researchers considered both primary and secondary Raynaud's phenomenon, evidence of moderate quality (downgraded for inconsistency) from 23 trials with 528 participants indicates that calcium channel blockers (CCBs) were superior to placebo in reducing the frequency of attacks. CCBs reduced the average number of attacks per week by six ( weighted mean difference (WMD) -6.13, 95% confidence interval (CI) -6.60 to - 5.67; I² = 98%) compared with 13.7 attacks per week with placebo. When review authors excluded Kahan 1985C, a trial showing a very large reduction in the frequency of attacks, data showed that CCBs reduced attack frequency by 2.93 per week (95% CI -3.44 to -2.43; I² = 77%).Low-quality evidence (downgraded for imprecision and inconsistency) from six trials with 69 participants suggests that the average duration of attacks did not differ in a statistically significant or clinically meaningful way between CCBs and placebo (WMD -1.67 minutes, 95% CI -3.29 to 0); this is equivalent to a -9% difference (95% CI -18% to 0%).Moderate-quality evidence (downgraded for inconsistency) based on 16 trials and 415 participants showed that CCBs reduced attack severity by 0.62 cm (95% CI -0.72 to - 0.51) on a 10-cm visual analogue scale (lower scores indicate less severity); this was equivalent to absolute and relative percent reductions of 6% (95% CI -11% to -8%) and 9% (95% CI -11% to -8%), respectively, which may not be clinically meaningful.Improvement in Raynaud's pain (low-quality evidence; downgraded for imprecision and inconsistency) and in disability as measured by a patient global assessment (moderate-quality evidence; downgraded for imprecision) favored CCBs (pain: WMD -1.47 cm, 95% CI -2.21 to -0.74; patient global: WMD -0.37 cm, 95% CI -0.73 to 0, when assessed on a 0 to 10 cm visual analogue scale, with lower scores indicating less pain and less disability). However, these effect estimates were likely underpowered, as they were based on limited numbers of participants, respectively, 62 and 92. For pain assessment, absolute and relative percent improvements were 15% (95% -22% to -7%) and 47% (95% CI -71% to -24%), respectively. For patient global assessment, absolute and relative percent improvements were 4% (95% CI -7% to 0%) and 9% (95% CI -19% to 0%), respectively.Subgroup analyses by Raynaud's type, CCB class, and CCB dose suggest that dihydropyridine CCBs in higher doses may be more effective for primary Raynaud's than for secondary Raynaud's, and CCBs likely have a greater effect in primary than in secondary Raynaud's. However, differences were small and were not found for all outcomes. Dihydropyridine CCBs were studied as they are the subgroup of CCBs that are not cardioselective and are traditionally used in RP treatment whereas other CCBs such as verapamil are not routinely used and diltiazem is not used as first line subtype of CCBs. Most trial data pertained to nifedipine.Withdrawals from studies due to adverse effects were inconclusive owing to a wide CI (risk ratio [RR] 1.30, 95% CI 0.51 to 3.33) from two parallel studies with 63 participants (low-quality evidence downgraded owing to imprecision and a high attrition rate); absolute and relative percent differences in withdrawals were 6% (95% CI -14% to 26%) and 30% (95% CI -49% to 233%), respectively. In cross-over trials, although a meta-analysis was not performed, withdrawals were more common with CCBs than with placebo. The most common side effects were headache, dizziness, nausea, palpitations, and ankle edema. However, in all trials, no serious adverse events (death or hospitalization) were reported.

AUTHORS' CONCLUSIONS

Randomized controlled trials with evidence of low to moderate quality showed that CCBs (especially the dihydropyridine class) may be useful in reducing the frequency, duration, severity of attacks, pain and disability associated with Raynaud's phenomenon. Higher doses may be more effective than lower doses and these CCBs may be more effective in primary RP. Although there were more withdrawals due to adverse events in the treatment groups, no serious adverse events were reported.

Ovariectomy does not affect the cardiac sympathovagal balance of female SHR but estradiol does

The low incidence of cardiovascular diseases, including hypertension, in premenopausal women has led to the conclusion that ovarian hormones may have a protective effect on the cardiovascular system. We evaluated the effects of ovariectomy and/or estradiol on sympathovagal balance and heart rate variability (HRV) in female spontaneously hypertensive rats (SHR) with tachycardia and compared them to Wistar rats (12 weeks old; N = 8-12). Ovariectomy (OVX) and/or estradiol (10 µg/kg) did not affect basal arterial pressure in either rat strain, but estradiol increased basal heart rate (HR) in OVX SHR (454 ± 18 vs 377 ± 9 bpm). HR changes elicited by methylatropine and propranolol were used to evaluate the sympathovagal balance. Ovariectomy did not affect the cardiac sympathovagal balance of any group, while estradiol increased sympathetic tone in OVX SHR (120 ± 8 vs 56 ± 10 bpm) and sham-operated Wistar rats (57 ± 7 vs 28 ± 4 bpm), and decreased the parasympathetic tone only in OVX SHR (26 ± 7 vs 37 ± 5 bpm). HRV was studied in the frequency domain (Fast Fourier Transformation). Spectra of HR series were examined at low frequency (LF: 0.2-0.75 Hz) and high frequency (HF: 0.75-3 Hz) bands. The power of LF, as well as the LF/HF ratio, was not affected by ovariectomy, but estradiol increased both LF (29 ± 4 vs 18 ± 3 nu in Wistar sham-operated, 26 ± 5 vs 15 ± 3 nu in Wistar OVX, 50 ± 3 vs 38 ± 4 nu in SHR sham-operated, and 51 ± 3 vs 42 ± 3 nu in SHR OVX) and LF/HF (0.48 ± 0.08 vs 0.23 ± 0.03 nu in Wistar sham-operated, 0.41 ± 0.14 vs 0.19 ± 0.05 nu in Wistar OVX, 0.98 ± 0.11 vs 0.63 ± 0.11 nu in SHR sham-operated, and 1.10 ± 0.11 vs 0.78 ± 0.1 nu in SHR OVX). Thus, we suggest that ovariectomy did not affect the cardiac sympathovagal balance of SHR or Wistar rats, while estradiol increased the sympathetic modulation of HR.

Effects of calcium channel blockers on antidepressant action of Alprazolam and Imipramine

Alprazolam is effective as an anxiolytic and in the adjunct treatment of depression. In this study, the effects of calcium channel antagonists on the antidepressant action of alprazolam and imipramine were investigated. A forced swimming maze was used to study behavioral despair in albino mice. Mice were divided into nine groups (n = 7 per group). One group received a single dose of 1% Tween 80; two groups each received a single dose of the antidepressant alone (alprazolam or imipramine); two groups each received a single dose of the calcium channel blocker (nifedipine or verapamil); four groups each received a single dose of the calcium channel blocker followed by a single dose of the antidepressant (with same doses used for either in the previous four groups). Drug administration was performed concurrently on the nine groups. Our data confirmed the antidepressant action of alprazolam and imipramine. Both nifedipine and verapamil produced a significant antidepressant effect (delay the onset of immobility) when administered separately. Verapamil augmented the antidepressant effects of alprazolam and imipramine (additive antidepressant effect). This may be due to the possibility that verapamil might have antidepressant-like effect through different mechanism. Nifedipine and imipramine combined led to a delay in the onset of immobility greater than their single use but less than the sum of their independent administration. This may be due to the fact that nifedipine on its own might act as an antidepressant but blocks one imipramine mechanism that depends on L-type calcium channel activation. Combining nifedipine with alprazolam produced additional antidepressant effects, which indicates that they exert antidepressant effects through different mechanisms.

Attenuation of contractile responses to sympathetic co-transmitters in veins from subjects with essential hypertension

Neuropeptide Y (NPY), noradrenaline (NA) and ATP are cotransmitters of the sympathetic nervous system and exert vasocontractile effects. The aim of this study was to determine the role of these sympathetic co-transmitters in human hypertension. Subcutaneous vessels from 12 patients with essential hypertension and 12 matched controls were studied in vitro. Vascular contractile responses to NPY, NA, alpha,beta-methylene ATP (alpha,beta-mATP) and potassium were studied in isolated arteries and veins (diameter 0.1-1.1 mm) with intact endothelium. The dilatory effect of acetylcholine was used to test the endothelial function. There was no difference in potency (pD2) or contractile response to NPY, NA or alpha,beta-mATP between hypertensive and control arteries. In veins, however, the contractile response to NPY was significantly reduced in hypertensives and the responses to NA were unchanged. Furthermore, the sensitivity (pD2) to alpha,beta-mATP was significantly reduced in veins from hypertensives. There was no difference in the dilatory response to acetylcholine between the hypertensives and the controls, neither in the arteries nor in the veins, indicating that the observed changes in vascular reactivity to NPY, NA and alpha,beta-mATP were not endothelium-dependent. In conclusion, the postjunctional contractile effect of NPY and sensitivity (pD2) to alpha,beta-mATP, co-transmitters of the peripheral sympathetic nervous system, are attenuated in veins in essential hypertension.