Acute and subacute effects of nicorandil and isosorbide dinitrate on vessel wall properties of large arteries and hemodynamics in healthy volunteers

Therapeutic potential of nicorandil beyond anti-anginal drug: A review on current and future perspectives

Nicorandil (NIC) is a well-known anti-anginal agent, which has been recommended as one of the second-line treatments for chronic stable angina as justified by the European guidelines. It shows an efficacy equivalent to that of classic anti-anginal agents. NIC has also been used clinically in various cardiovascular diseases such as variant or unstable angina and reperfusion-induced damage following coronary angioplasty or thrombolysis. Different mechanisms have been involved in the protective effects of nicorandil in various diseases, including opening of adenosine triphosphate-sensitive potassium (KATP) channel and donation of nitric oxide (NO). In recent years, NIC has been found to show numerous pharmacological activities such as neuroprotective, nephroprotective, hepatoprotective, cardioprotective, and testicular protective effects, among other beneficial effects on the body. The present review dwells on the pharmacological potentials of NIC beyond its anti-anginal action.

Prognostic Impact of Chronic Vasodilator Therapy in Patients With Vasospastic Angina

Background

Chronic vasodilator therapy with long‐acting nitrate is frequently used to treat vasospastic angina. However, the clinical benefits of this approach are controversial. We investigated the prognostic impact of vasodilator therapy in patients with vasospastic angina from the multicenter, prospective VA‐KOREA (Vasospastic Angina in KOREA) registry.

Methods and Results

We analyzed data from 1895 patients with positive intracoronary ergonovine provocation test results. The patients were divided into 4 groups: no vasodilator (n=359), nonnitrate vasodilator (n=1187), conventional nitrate (n=209), and a combination of conventional nitrate and other vasodilators (n=140). The primary end point was a composite of cardiac death, acute coronary syndrome, and new‐onset arrhythmia at 2 years. Secondary end points were the individual components of the primary end point, all‐cause death, and rehospitalization due to recurrent angina.

The groups did not differ in terms of the risk of the primary end point. However, the acute coronary syndrome risk was significantly higher in the conventional nitrate (hazard ratio [HR], 2.49; 95% CI, 1.01–6.14; P=0.047) and combination groups (HR, 3.34; 95% CI, 1.15–9.75, P=0.027) compared with the no‐vasodilator group, as assessed using the inverse probability of treatment weights. Subgroup analyses revealed prominent adverse effects of nitrate in patients with an intermediate positive ergonovine provocation test result and in those with low Japanese Coronary Spasm Association scores.

Conclusions

Long‐acting nitrate‐based chronic vasodilator therapy was associated with an increased 2‐year risk of acute coronary syndrome in patients with vasospastic angina, especially in low‐risk patients.

The Role of Nicorandil in the Management of Chronic Coronary Syndromes in the Gulf Region

Chronic coronary syndromes (CCS) and stable angina are a growing clinical burden worldwide. This is of particular concern in the Gulf region given its high prevalence of cardiovascular risk factors, especially diabetes mellitus and smoking. Despite recommendations on the use of first- and second-line anti-anginal medication, management challenges remain. Current guidelines for pharmacologic treatment are not determined by the range of pathophysiological mechanisms of ischaemia and consequent angina, which may occur either in isolation or co-exist. In this article, we highlight the need to improve knowledge of the epidemiology of chronic coronary syndromes in the Middle East and Gulf region, and the need for studies of stratified pharmacologic approaches to improve symptomatic angina and quality of life in the large and growing number of patients with coronary artery disease from this region. We discuss the role of nicorandil, currently recommended as a second-line anti-anginal drug in CCS patients, and suggest that this may be a particularly useful add-on therapy for patients in the Gulf region.

Impact of different nitrate therapies on long-term clinical outcomes of patients with vasospastic angina: A propensity score-matched analysis

BACKGROUND

Despite the short-term vasodilatory effects of nitrates, the prognostic effects of long-term nitrate therapy in patients with vasospastic angina (VSA) remains unclear. We investigated the prognostic impact of chronic nitrate therapy in VSA patients.

METHODS

Between January 2003 and December 2014, a total of 1154 VSA patients proven by ergonovine provocation tests were classified into nitrate (n=676) and non-nitrate (n=478) groups according to prescriptions for oral nitrates, including isosorbide mononitrate (ISMN) and nicorandil. The primary outcome was major adverse cardiovascular events (MACE), defined as a composite of cardiac death, myocardial infarction, any revascularization, or rehospitalization due to recurrent angina.

RESULTS

The nitrate group was found to have a higher risk of MACE (22.9% vs. 17.6%, hazard ratio [HR] 1.32, 95% confidence interval [CI] 1.01-1.73, p=0.043) than the non-nitrate group. After propensity score matching, the nitrate group had greater risks of MACE (HR 1.32, 95%CI 1.01-1.73, p=0.049). Patients who received the immediate-release formula of ISMN (HR 1.80, 95%CI 1.35-2.39, p<0.001) or were administered any forms of ISMN other than at bedtime (HR 1.90, 95%CI 1.41-2.57, p<0.001) had a significantly higher risk of MACE compared with the non-nitrate group. Nicorandil was shown to have a neutral effect on VSA patients (HR 1.11, 95%CI 0.73-1.69, p=0.62).

CONCLUSIONS

The long-term use of nitrate therapy was associated with increased risk of adverse cardiac events in VSA patients. The use of immediate-release ISMN or the administration of ISMN other than at bedtime was related with poor outcomes of VSA patients.

Nicorandil and Long-acting Nitrates: Vasodilator Therapies for the Management of Chronic Stable Angina Pectoris

Nicorandil and long-acting nitrates are vasodilatory drugs used commonly in the management of chronic stable angina pectoris. Both nicorandil and long-acting nitrates exert anti-angina properties via activation of nitric oxide (NO) signalling pathways, triggering vascular smooth muscle cell relaxation. Nicorandil has additional actions as an arterial K⁺ _ATP channel agonist, resulting in more "balanced" arterial and venous vasodilatation than nitrates. Ultimately, these drugs prevent angina symptoms through reductions in preload and diastolic wall tension and, to a lesser extent, epicardial coronary artery dilatation and lowering of systemic blood pressure. While there is some evidence to suggest a modest reduction in cardiovascular events among patients with stable angina treated with nicorandil compared to placebo, this prognostic benefit has yet to be proven conclusively. In contrast, there is emerging evidence to suggest that chronic use of long-acting nitrates might cause endothelial dysfunction and increased cardiovascular risk in some patients.

Vasodilator Therapy: Nitrates and Nicorandil

Nitrates have been used to treat symptoms of chronic stable angina for over 135 years. These drugs are known to activate nitric oxide (NO)-cyclic guanosine-3',-5'-monophasphate (cGMP) signaling pathways underlying vascular smooth muscle cell relaxation, albeit many questions relating to how nitrates work at the cellular level remain unanswered. Physiologically, the anti-angina effects of nitrates are mostly due to peripheral venous dilatation leading to reduction in preload and therefore left ventricular wall stress, and, to a lesser extent, epicardial coronary artery dilatation and lowering of systemic blood pressure. By counteracting ischemic mechanisms, short-acting nitrates offer rapid relief following an angina attack. Long-acting nitrates, used commonly for angina prophylaxis are recommended second-line, after beta-blockers and calcium channel antagonists. Nicorandil is a balanced vasodilator that acts as both NO donor and arterial K(+) ATP channel opener. Nicorandil might also exhibit cardioprotective properties via mitochondrial ischemic preconditioning. While nitrates and nicorandil are effective pharmacological agents for prevention of angina symptoms, when prescribing these drugs it is important to consider that unwanted and poorly tolerated hemodynamic side-effects such as headache and orthostatic hypotension can often occur owing to systemic vasodilatation. It is also necessary to ensure that a dosing regime is followed that avoids nitrate tolerance, which not only results in loss of drug efficacy, but might also cause endothelial dysfunction and increase long-term cardiovascular risk. Here we provide an update on the pharmacological management of chronic stable angina using nitrates and nicorandil.

Involvement of guanylate cyclase and K+ channels in relaxation evoked by ferulate nitrate in rat aorta artery

Vasorelaxant properties of N-2-(ferulamidoethyl)-nitrate (ferulate nitrate, FLNT), a newly synthesized nitrate, were compared with those of isosorbide dinitrate, nicorandil, nitroglycerin, and 8-bromoguanosine 3,5-cyclic monophosphate (8-Br-cGMP) in rat aorta pre-contracted by phenylephrine. FLNT produced vasorelaxation in a concentration-dependent manner (0.1 - 100 µM). The degree of relaxation induced by FLNT was similar to that induced by isosorbide dinitrate. In addition, removal of endothelium did not affect the relaxant effect of FLNT. FLNT caused a rightward shift of the cumulative concentration-response curves of phenylephrine and reduced the maximal efficacy of contraction. 1H-[1,2,4]Oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ, 10 µM) and K(+)-channel blockers charybdotoxin (CHT, 0.1 µM) and BaCl(2) (1 µM) reduced the relaxant effect of FLNT in the endothelium-denuded arteries, whereas glibenclamide (1 µM) and 4-aminopyridine (1 mM) failed to influence FLNT-induced vasorelaxation. Furthermore, in the presence of ODQ, both CHT (0.1 µM) and BaCl(2) (1 µM) still significantly reduced the relaxation evoked by FLNT. Pretreatment of vessels with hydroxocobalamin, a nitric oxide scavenger, abolished the FLNT effect. These findings demonstrate that FLNT induces relaxation of the rat aorta rings endothelium-independently. Furthermore, we demonstrated that FLNT-induced vasorelaxation is related to its stimulation of soluble guanylate cyclase and activation of K(+) channels.

Pharmacological modulation of arterial stiffness

Arterial stiffness has emerged as an important marker of cardiovascular risk in various populations and reflects the cumulative effect of cardiovascular risk factors on large arteries, which in turn is modulated by genetic background. Arterial stiffness is determined by the composition of the arterial wall and the arrangement of these components, and can be studied in humans non-invasively. Age and distending pressure are two major factors influencing large artery stiffness. Change in arterial stiffness with drugs is an important endpoint in clinical trials, although evidence for arterial stiffness as a therapeutic target still needs to be confirmed. Drugs that independently affect arterial stiffness include antihypertensive drugs, mostly blockers of the renin-angiotensin-aldosterone system, hormone replacement therapy and some antidiabetic drugs such as glitazones. While the quest continues for 'de-stiffening drugs', so far only advanced glycation endproduct cross-link breakers have shown promise.

Clinical applications of arterial stiffness: therapeutics and pharmacology

This short review describes the effects of drugs and nonpharmacologic treatments on large artery stiffness in clinical trials. Arterial stiffness is generally accepted as a predictive factor for cardiovascular morbidity and mortality. The drug-induced reduction in arterial stiffness may parallel the reduction in cardiovascular work. This review summarizes the discussion of a task force that worked on the therapeutic aspects during a Consensus Conference on the 'Clinical applications of arterial stiffness," held in Paris on June 17, 2000. The effects of drugs on arterial stiffness are detailed in patients with hypertension, heart failure, and other arterial diseases. Other issues are raised, including the reversibility of arterial changes following pharmacologic treatment, and the possibility for nonpharmacologic treatment to be effective on arterial stiffness. Directions for future therapeutic trials are suggested.

Is it possible to develop drugs that act more selectively on large arteries?

BACKGROUND

Patients with high pulse pressures have an increased risk for cardiovascular events. Drugs that selectively decrease high pulse pressure may be of interest for these patients. Such drugs have a more pronounced effect on large arteries than on resistance vessels.

OBJECTIVE

To compare the selectivity to large arteries of the new nitric oxide donor sinitrodil with the classic nitrate isosorbide dinitrate in healthy young men in order to investigate whether it is possible to develop drugs that act more selectively on large arteries.

DESIGN

The study had a double-blind, 5-way cross-over design. In randomized order, subjects received a single oral dose of 10 mg sinitrodil, 20 mg sinitrodil, 40 mg sinitrodil, isosorbide dinitrate and placebo. Measurements were performed before and 45 min after administration of the drugs. Between each drug administration, at least 3 days of wash-out was allowed.

METHODS

The effects of the drugs on large arteries and resistance vessels were assessed by their effects on brachial artery compliance and total peripheral resistance, respectively.

RESULTS

Brachial artery compliance increased gradually with increasing doses of sinitrodil (by 10, 20 and 27% with 10, 20 and 40 mg sinitrodil, respectively). Total peripheral resistance index decreased with isosorbide dinitrate (by 11%) and 40 mg sinitrodil (by 7%), while it remained unchanged with 10 mg and 20 mg sinitrodil.

CONCLUSIONS

The results of this study show that it may be possible to develop drugs with a higher selectivity for large arteries. Such drugs may be good candidates to decrease high pulse pressure without substantially decreasing mean and diastolic blood pressures.

[Nicorandil: acute hemodynamic effects of 2 different oral doses of a potassium channel opener in patients with coronary heart disease]

BACKGROUND

In medical treatment of angina pectoris the 3 major groups of antianginal agents are nitrates, beta blockers and calcium antagonists. Now a new class of drugs is introduced in the therapy: the potassium channel openers. One of the first potassium channel openers is nicorandil. We examined the acute hemodynamic effects of 2 different oral nicorandil doses in patients with coronary heart disease.

PATIENTS AND METHODS

Twenty patients with angiographic proven coronary heart disease and stable angina pectoris were treated with a dose of 2 x 10 mg Nicorandil on day 1 and 2 x 20 mg Nicorandil on day 2, while being hemodynamically monitored on an intensive care unit with a pulmonary artery catheter.

RESULTS

Through the hemodynamic monitoring a dose dependent, significant reduction of systolic blood pressure was found (6%/9%), while the heart rate increased dose dependently (6%/11%). The rate pressure product as a marker of myocardial oxygen demand did not increase significantly.

CONCLUSION

The oral application of nicorandil causes an acute, dose dependent, significant decrease in systolic blood pressure and induces a reflextachycardia.

Effects of antihypertensive agents on local arterial distensibility and compliance

Distensibility and compliance are important vessel wall properties. Distensibility is related to elastic properties of the arterial wall, and compliance reflects the buffering function of the artery. Distensibility is a determinant of stress on the vessel wall. A decreased distensibility might increase the risk of arterial wall damage. Therefore, a preserved local distensibility might be important in protecting the arterial wall of each particular artery and especially of those arteries that are more susceptible to vascular disease. Local distensibility and compliance of various large arteries can be measured noninvasively with echo tracking techniques. Studies on local distensibility and compliance revealed that with the calcium antagonist verapamil and the angiotensin-converting enzyme inhibitor perindopril arterial compliance increased mainly because of an increase in distensibility, with only a minor effect on arterial diameter. In contrast, the nitrate compound isosorbide dinitrate increased compliance mainly by increasing arterial diameter, without an increase in distensibility. This indicates that an increase in arterial compliance does not automatically imply an increase in arterial distensibility. The effect of antihypertensive drugs may also depend on the vascular territory. The diuretic amiloride/hydrochlorothiazide increased brachial artery compliance but not common carotid artery compliance. During angiotensin-converting enzyme inhibition the effect on arterial compliance was smaller at the carotid than the femoral artery. However, the opposite held for the nitrate compound. These distinctive effects of antihypertensive drugs on arterial distensibility and compliance and on vascular territories may be relevant to pharmacological prevention and management of arterial disease.