Expanding the understanding of the treatment of chronic angina: a 21st century approach-part II

Three randomized, clinical trials of the drug ranolazine relate to patients with symptomatic myocardial ischemia. A fourth randomized, controlled, clinical trial compares optimal medical therapy with percutaneous coronary intervention (PCI) plus medical therapy.

What's new in clinical pharmacology and therapeutics

The US Food and Drug Administration (FDA) has approved several new drugs in the past 2 years. This article provides an overview of some of the newer drugs that are likely to find wider use in the future. The drugs reviewed in this article can be used to treat cardiovascular system problems, diabetes mellitus, multiple sclerosis, hepatitis B infection, hyponatremia, Parkinson's disease, rheumatoid arthritis, pain, constipation, and insomnia. Another drug discussed can be used to help a patient stop smoking. The article also discusses Gardasil, the recombinant vaccine against human papilloma virus (types 6, 11, 16, and 18).

Mechanism of action of the new anti-ischemia drug ranolazine

Myocardial ischemia is associated with reduced ATP fluxes and decreased energy supply resulting in disturbances of intracellular ion homeostasis in cardiac myocytes. In the recent years, increased persistent (late) sodium current was suggested to contribute to disturbed ion homeostasis by elevating intracellular sodium concentration with subsequent elevation of intracellular calcium. The new anti-ischemia drug ranolazine, a specific inhibitor of late sodium current, reduces sodium overload and hence ameliorates disturbed ion homeostasis. This is associated with symptomatic improvement of angina in patients. Moreover, ranolazine was shown to exhibit anti-arrhythmic effects. In the present article, we review the relevant pathophysiological concepts for the role of late sodium inhibition and summarize the most recent data from basic as well as clinical studies.

The cardiac persistent sodium current: an appealing therapeutic target?

The sodium current in the heart is not a single current with a mono-exponential decay but rather a mixture of currents with different kinetics. It is not clear whether these arise from distinct populations of channels, or from modulation of a single population. A very slowly inactivating component, [(INa(P))] I(Na(P)) is usually about 1% of the size of the peak transient current [I(Na(T))], but is enhanced by hypoxia. It contributes to Na(+) loading and cellular damage in ischaemia and re-perfusion, and perhaps to ischaemic arrhythmias. Class I antiarrhythmic agents such as flecainide, lidocaine and mexiletine generally block I(NA(P)) more potently than block of I(Na(T)) and have been used clinically to treat LQT3 syndrome, which arises because mutations in SCN5A produce defective inactivation of the cardiac sodium channel. The same approach may be useful in some pathological situations, such as ischaemic arrhythmias or diastolic dysfunction, and newer agents are being developed with this goal. For example, ranolazine blocks I(Na(P)) about 10 times more potently than I(Na(T)) and has shown promise in the treatment of angina. Alternatively, the combination of I(Na(P)) block with K(+) channel block may provide protection from the induction of Torsades de Pointe when these agents are used to treat atrial arrhythmias (eg Vernakalant). In all of these scenarios, an understanding of the role of I(Na(P)) in cardiac pathophysiology, the mechanisms by which it may affect cardiac electrophysiology and the potential side effects of blocking I(Na(P)) in the heart and elsewhere will become increasingly important.

[Determination of residual solvents in ranolazine by headspace gas chromatography]

OBJECTIVE

To determine the contents of the residual solvents, methanol, ethanol, toluene, dichloromethane and dioxane in ranolazine raw material.

METHODS

Headspace gas chromatography was used to analyze the residual solvents quantitatively. Samples were analyzed on an HP-INNOWAX column with column temperature at 45 degrees Celsius; using water as solvent.

RESULTS

Five residual solvents were completely separated. The liner range and recoveries were satisfied. RSD of precision and accuracy was less than 8% with average recoveries between 87.1% and 105.6%.

CONCLUSION

The method could be used for the quality control of ranolazine raw material.

Effect of Ranolazine, an Antianginal Agent With Novel Electrophysiological Properties, on the Incidence of Arrhythmias in Patients With Non–ST-Segment–Elevation Acute Coronary Syndrome

Background— Ranolazine, a piperazine derivative, reduces ischemia via inhibition of the late phase of the inward sodium current (late I Na ) during cardiac repolarization, with a consequent reduction in intracellular sodium and calcium overload. Increased intracellular calcium leads to both mechanical dysfunction and electric instability. Ranolazine reduces proarrhythmic substrate and triggers such as early afterdepolarization in experimental models. However, the potential antiarrhythmic actions of ranolazine have yet to be demonstrated in humans.

Methods and Results— The Metabolic Efficiency With Ranolazine for Less Ischemia in Non–ST-Elevation Acute Coronary Syndrome (MERLIN)–Thrombolysis in Myocardial Infarction (TIMI) 36 (MERLIN-TIMI 36) trial randomized 6560 patients hospitalized with a non–ST-elevation acute coronary syndrome to ranolazine or placebo in addition to standard therapy. Continuous ECG (Holter) recording was performed for the first 7 days after randomization. A prespecified set of arrhythmias were evaluated by a core laboratory blinded to treatment and outcomes. Of the 6560 patients in MERLIN-TIMI 36, 6351 (97%) had continuous ECG recordings that could be evaluated for arrhythmia analysis. Treatment with ranolazine resulted in significantly lower incidences of arrhythmias. Specifically, fewer patients had an episode of ventricular tachycardia lasting ≥8 beats (166 [5.3%] versus 265 [8.3%]; P <0.001), supraventricular tachycardia (1413 [44.7%] versus 1752 [55.0%]; P <0.001), or new-onset atrial fibrillation (55 [1.7%] versus 75 [2.4%]; P =0.08). In addition, pauses ≥3 seconds were less frequent with ranolazine (97 [3.1%] versus 136 [4.3%]; P =0.01).

Conclusions— Ranolazine, an inhibitor of late I Na , appears to have antiarrhythmic effects as assessed by continuous ECG monitoring of patients in the first week after admission for acute coronary syndrome. Studies specifically designed to evaluate the potential role of ranolazine as an antiarrhythmic agent are warranted.

Atrium-selective sodium channel block as a strategy for suppression of atrial fibrillation: differences in sodium channel inactivation between atria and ventricles and the role of ranolazine

BACKGROUND

The development of selective atrial antiarrhythmic agents is a current strategy for suppression of atrial fibrillation (AF).

METHODS AND RESULTS

Whole-cell patch clamp techniques were used to evaluate inactivation of peak sodium channel current (I(Na)) in myocytes isolated from canine atria and ventricles. The electrophysiological effects of therapeutic concentrations of ranolazine (1 to 10 micromol/L) and lidocaine (2.1 to 21 micromol/L) were evaluated in canine isolated coronary-perfused atrial and ventricular preparations. Half-inactivation voltage of I(Na) was approximately 15 mV more negative in atrial versus ventricular cells under control conditions; this difference increased after exposure to ranolazine. Ranolazine produced a marked use-dependent depression of sodium channel parameters, including the maximum rate of rise of the action potential upstroke, conduction velocity, and diastolic threshold of excitation, and induced postrepolarization refractoriness in atria but not in ventricles. Lidocaine also preferentially suppressed these parameters in atria versus ventricles, but to a much lesser extent than ranolazine. Ranolazine produced a prolongation of action potential duration (APD90) in atria, no effect on APD90 in ventricular myocardium, and an abbreviation of APD90 in Purkinje fibers. Lidocaine abbreviated both atrial and ventricular APD90. Ranolazine was more effective than lidocaine in terminating persistent AF and in preventing the induction of AF.

CONCLUSIONS

Our study demonstrates important differences in the inactivation characteristics of atrial versus ventricular sodium channels and a striking atrial selectivity for the action of ranolazine to produce use-dependent block of sodium channels, leading to suppression of AF. Our results point to atrium-selective sodium channel block as a novel strategy for the management of AF.

Ranolazine in patients with coronary artery disease

Traditional anti-anginal agents such as beta-blockers and nitrates improve symptoms of cardiac ischemia by affecting either blood pressure or heart rates. Despite aggressive therapy, many patients suffer persistent angina, and optimal therapy is limited by intolerance to traditional agents. Ranolazine, a novel anti-anginal agent that is approved for use in the US, is felt to improve ischemic symptoms by reducing myocardial cellular sodium and calcium overload via inhibition of the late sodium current (I(Na)) of the cardiac action potential. Several Phase-III trials in patients with chronic angina have demonstrated that ranolazine improves exercise tolerance and reduces ischemic symptoms as compared with placebo. In the largest evaluation of ranolazine, the MERLIN-TIMI 36 trial (Metabolic Efficiency with Ranolazine for Less Ischemia in non ST elevation acute coronary syndrome), ranolazine did not reduce the risk of death or recurrent myocardial infarction in patients with non-ST-elevation acute coronary syndromes, but it did improve ischemic symptoms over the subsequent year of therapy. Thus, ranolazine offers clinicians a new therapy in the long-term treatment of patients with chronic angina.

Ranolazine in patients with angina and coronary artery disease

The optimal management of coronary artery disease is based on achieving two parallel objectives: 1) prevention of major cardiovascular events, and 2) resolution of symptoms. Traditional antianginal agents improve ischemic symptoms by reducing myocardial oxygen demand through modulation of heart rate, preload, and/or afterload. Ranolazine is a novel antianginal agent believed to relieve ischemia by reducing myocardial cellular sodium and calcium overload via inhibition of the late sodium current of the cardiac action potential. In three randomized double-blind trials in selected patients with chronic angina, ranolazine prolonged exercise duration and reduced symptoms when compared with placebo when given as either monotherapy or in combination with traditional antianginal pharmacotherapy. When evaluated in patients with non-ST-elevation acute coronary syndromes, ranolazine reduced recurrent ischemia but did not significantly reduce the risk of death or myocardial infarction at 1 year. Ranolazine complements traditional antianginal agents and offers clinicians a new option in the long-term treatment of patients with angina.

Molecular basis of ranolazine block of LQT-3 mutant sodium channels: evidence for site of action

1 We studied the effects of ranolazine, an antianginal agent with promise as an antiarrhythmic drug, on wild-type (WT) and long QT syndrome variant 3 (LQT-3) mutant Na(+) channels expressed in human embryonic kidney (HEK) 293 cells and knock-in mouse cardiomyocytes and used site-directed mutagenesis to probe the site of action of the drug. 2 We find preferential ranolazine block of sustained vs peak Na(+) channel current for LQT-3 mutant (DeltaKPQ and Y1795C) channels (IC(50)=15 vs 135 microM) with similar results obtained in HEK 293 cells and knock-in myocytes. 3 Ranolazine block of both peak and sustained Na(+) channel current is significantly reduced by mutation (F1760A) of a single residue previously shown to contribute critically to the binding site for local anesthetic (LA) molecules in the Na(+) channel. 4 Ranolazine significantly decreases action potential duration (APD) at 50 and 90% repolarization by 23+/-5 and 27+/-3%, respectively, in DeltaKPQ mouse ventricular myocytes but has little effect on APD of WT myocytes. 5 Computational modeling of human cardiac myocyte electrical activity that incorporates our voltage-clamp data predicts marked ranolazine-induced APD shortening in cells expressing LQT-3 mutant channels. 6 Our results demonstrate for the first time the utility of ranolazine as a blocker of sustained Na(+) channel activity induced by inherited mutations that cause human disease and further, that these effects are very likely due to interactions of ranolazine with the receptor site for LA molecules in the sodium channel.

Ranolazine and late cardiac sodium current--a therapeutic target for angina, arrhythmia and more?

Ranolazine is a new antianginal drug approved for clinical use in the United States in January 2006. A study published in this same issue of the British Journal of Pharmacology characterizes ranolazine block of late sodium current caused by the long QT syndrome 3 mutations. This commentary discusses the implications of that study and the background and implications for block of late cardiac sodium current in general.

Safety and Efficacy of Extended-Release Ranolazine in Patients Aged 70 Years or Older With Chronic Stable Angina Pectoris

This analysis examined the safety and efficacy of extended-release ranolazine among patients aged 70 years or older (n=363) compared with patients younger than 70 years (n=1024) enrolled in 2 large multinational prospective clinical trials. The primary end points were exercise capacity and number of weekly angina episodes. Beneficial effects of ranolazine, relative to placebo, were generally similar for each of these outcomes among older and younger participants. For example, at a ranolazine dose of 1000 mg bid, mean exercise duration increased by 19.8+/-13.1 seconds (mean +/- SE) relative to placebo in patients younger than 70 years and by 32.4+/-19.7 seconds relative to placebo in patients 70 years or older. Adverse effects were more common in older than in younger patients, but the incidence of serious adverse effects attributable to ranolazine did not differ significantly between age groups. Outcomes were also similar at dosages of either 750 mg or 1000 mg bid. In conclusion, pooled data from 2 large randomized trials indicate that the efficacy of ranolazine is similar in older and younger patients but that adverse effects are more common in the elderly.

Ranolazine: a novel agent that improves dysfunctional sodium channels

Treatment for coronary heart disease is usually directed at either increasing myocardial oxygen supply or decreasing myocardial oxygen demand. Although combination therapy with beta-blockers, calcium-channel blockers and nitrates are effective, many patients suffer from adverse effects of hypotension and bradycardia. Ranolazine is a novel medication that reduces ischaemia by preventing sodium induced calcium overload in myocardial cells without adversely affecting haemodynamic parameters. This agent is the first in the USA to be approved to treat angina in over 10 years. The purpose of this review is to evaluate the pharmacology, pharmacokinetics, clinical trials for safety and efficacy, precautions, adverse effects, drug interactions, and dosage and administration of ranolazine in the treatment of chronic stable angina and acute coronary syndrome.

Effects of ranolazine on recurrent cardiovascular events in patients with non-ST-elevation acute coronary syndromes: the MERLIN-TIMI 36 randomized trial

CONTEXT

Ranolazine is a novel antianginal agent that reduces ischemia in patients with chronic angina but has not been studied in patients with acute coronary syndromes (ACS).

OBJECTIVE

To determine the efficacy and safety of ranolazine during long-term treatment of patients with non-ST-elevation ACS.

DESIGN, SETTING, AND PATIENTS

A randomized, double-blind, placebo-controlled, multinational clinical trial of 6560 patients within 48 hours of ischemic symptoms who were treated with ranolazine (initiated intravenously and followed by oral ranolazine extended-release 1000 mg twice daily, n = 3279) or matching placebo (n = 3281), and followed up for a median of 348 days in the Metabolic Efficiency With Ranolazine for Less Ischemia in Non-ST-Elevation Acute Coronary Syndromes (MERLIN)-TIMI 36 trial between October 8, 2004, and February 14, 2007.

MAIN OUTCOME MEASURES

The primary efficacy end point was a composite of cardiovascular death, myocardial infarction (MI), or recurrent ischemia through the end of study. The major safety end points were death from any cause and symptomatic documented arrhythmia.

RESULTS

The primary end point occurred in 696 patients (21.8%) in the ranolazine group and 753 patients (23.5%) in the placebo group (hazard ratio [HR], 0.92; 95% confidence interval [CI], 0.83-1.02; P = .11). The major secondary end point (cardiovascular death, MI, or severe recurrent ischemia) occurred in 602 patients (18.7%) in the ranolazine group and 625 (19.2%) in the placebo group (HR, 0.96; 95% CI, 0.86-1.08; P = .50). Cardiovascular death or MI occurred in 338 patients (10.4%) allocated to ranolazine and 343 patients (10.5%) allocated to placebo (HR, 0.99; 95% CI, 0.85-1.15; P = .87). Recurrent ischemia was reduced in the ranolazine group (430 [13.9%]) compared with the placebo group (494 [16.1%]; HR, 0.87; 95% CI, 0.76-0.99; P = .03). QTc prolongation requiring a reduction in the dose of intravenous drug occurred in 31 patients (0.9%) receiving ranolazine compared with 10 patients (0.3%) receiving placebo. Symptomatic documented arrhythmias did not differ between the ranolazine (99 [3.0%]) and placebo (102 [3.1%]) groups (P = .84). No difference in total mortality was observed with ranolazine compared with placebo (172 vs 175; HR, 0.99; 95% CI, 0.80-1.22; P = .91).

CONCLUSIONS

The addition of ranolazine to standard treatment for ACS was not effective in reducing major cardiovascular events. Ranolazine did not adversely affect the risk of all-cause death or symptomatic documented arrhythmia. Our findings provide support for the safety and efficacy of ranolazine as antianginal therapy.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00099788.

Spotlight on ranolazine in chronic stable angina pectoris

Ranolazine (Ranexa), a piperazine derivative, is a new antianginal agent approved for the treatment of chronic stable angina pectoris for use as combination therapy when angina is not adequately controlled with other antianginal agents. While the exact mechanism of action of ranolazine is not known, its antianginal and anti-ischemic effects do not appear to depend upon changes in BP or heart rate. An extended-release (ER) oral formulation of ranolazine has been developed to facilitate twice-daily administration whilst maintaining therapeutically effective plasma concentrations. In patients with chronic stable angina, ranolazine ER monotherapy was shown to improve exercise duration at trough plasma drug concentration in a dose-dependent manner compared with placebo. The drug was effective as adjunctive therapy in patients with chronic stable angina whose condition was not controlled adequately with conventional antianginal therapy. In randomized clinical trials, ranolazine ER was well tolerated, with no overt effects on cardiovascular hemodynamics or conduction, apart from a modest increase in corrected QT interval (but no torsades de pointes). Importantly, the efficacy and tolerability of ranolazine ER were not affected by old age and co-morbid conditions (heart failure or diabetes mellitus). Comparative trials of ranolazine ER with other antianginal agents and trials examining its effects on long-term morbidity and mortality in patients with ischemic heart disease are required to determine with greater certainty the place of the drug in current antianginal therapy. Nevertheless, ranolazine ER may well prove to be a useful alternative and adjunct to conventional hemodynamic antianginal therapy in the treatment of chronic stable angina.

Long-term safety of a novel antianginal agent in patients with severe chronic stable angina: the Ranolazine Open Label Experience (ROLE)

OBJECTIVES

This report describes safety and tolerability data from 746 chronic angina patients treated in the ROLE (Ranolazine Open Label Experience) program.

BACKGROUND

Ranolazine treats angina without depressing hemodynamic status. The long-term safety and tolerability of ranolazine have not been previously reported.

METHODS

Patients with severe functional impairment from angina (mean Duke Treadmill Score [DTS] of -14.4) who completed 1 of 2 randomized treadmill trials entered the ROLE program. Ranolazine was titrated to optimal dosages between 500 and 1,000 mg twice daily. Physical examination, laboratory tests, and adverse event reporting were performed periodically. We conducted analyses to evaluate possible predictors of ranolazine intolerance, such as advanced age, diabetes, poor exercise tolerance, or history of myocardial infarctions or congestive heart failure (CHF). The ROLE program's mortality was compared against the DTS predictive model and other contemporary cohorts of high-risk CHD patients.

RESULTS

Mean follow-up was 2.82 years. Two years after initial dosing, 571 patients (76.7%) remained on therapy and 72 patients (9.7%) discontinued ranolazine due to adverse events. Among 6 factors evaluated, only age > or =64 years predicted for higher withdrawal rates. Patients with a history of CHF had lower withdrawal rates. Mean QTc interval was prolonged by 2.4 ms. No treatment discontinuations occurred due to QTc prolongation, and no Torsades de Pointes was reported. Sixty-four deaths occurred during a total of 2,102 patient-years (3.0% annually) during the ROLE program. When extending observations to all patients exposed to ranolazine during the double-blind trials (n = 972) preceding the ROLE program, annual mortality was 2.8% compared with >5% as predicted by DTS.

CONCLUSIONS

Long-term therapy with ranolazine seems well tolerated in high-risk CHD patients. Survival analyses suggest that symptomatic improvements attributable to ranolazine are not offset by increased mortality.

Novel therapeutic approaches to treating chronic angina in the setting of chronic ischemic heart disease

Pharmacologic therapy to alleviate symptoms in chronic angina has been enhanced by the recent approval of several novel compounds that complement the traditional approach using beta-adrenergic blocking drugs, calcium antagonists, and long-acting nitrates. In the United States, ranolazine, a drug that inhibits late I(Na), was approved for patients with chronic angina that remain symptomatic on beta-blockers, calcium antagonists, or long-acting nitrates, on the basis of an acceptable safety profile and efficacy in several randomized placebo controlled studies. A slight increase in the QT interval is observed (<10 ms on average) at the maximum approved dose of 1,000 mg twice daily. Therefore, an ECG should be acquired at baseline and during follow-up, and the drug should not be used in patients with QT prolongation or those who are on QT prolonging drugs unless longer term randomized outcome data demonstrates no excess risk. The MERLIN trial of non-ST-elevation acute coronary syndrome (NSTE ACS) randomized 6,560 patients to assess the potential benefit of ranolazine in reducing the composite endpoint of cardiovascular death, myocardial infarction, and recurrent ischemia, with results expected in 2007. In Europe, ivabradine, a drug that inhibits the hyperpolarization-activated mixed sodium/potassium inward I(f) current, which slows the rest and exercise heart rate, was approved in 2005. Ivabradine at a dose of 10 mg twice daily has been shown to have similar efficacy to amlodipine 10 mg once daily or atenolol 100 mg once daily in alleviating chronic angina symptoms. In this review, several other novel investigational approaches are presented and patient selection considerations for the most recent approved drugs for chronic angina are discussed.