Ranolazine

Ranolazine (RS-43285) is a racemic piperazine acetamide derivative and the first selective inhibitor of the cardiac late sodium current (INaL) approved for clinical use, registered by the United States Food and Drug Administration in January 2006 for the treatment of chronic stable angina pectoris and subsequently authorized in the European Union and other jurisdictions under the trade name Ranexa. The compound occupies a mechanistically unique position among antianginal agents: unlike beta-adrenergic antagonists, calcium channel blockers, and organic nitrates, ranolazine produces anti-ischemic and antianginal effects without clinically meaningful reductions in heart rate, blood pressure, or rate-pressure product, instead acting through selective inhibition of the persistent (late) component of the cardiac voltage-gated sodium channel (NaV1.5) that is pathologically augmented in ischemia, heart failure, and inherited channelopathies.

The late sodium current mechanism was formally characterized by Belardinelli, Bhatt, Bhagat, and colleagues at CV Therapeutics in the early 2000s, superseding an earlier metabolic hypothesis that attributed the antianginal effect to partial inhibition of fatty acid beta-oxidation (pFOX). At therapeutic plasma concentrations (2 to 6 micromolar), ranolazine inhibits INaL with an IC50 of approximately 5 to 7 micromolar while sparing peak sodium current (IC50 approximately 244 micromolar), producing an approximately 38-fold selectivity ratio that distinguishes the compound from classical sodium channel blockers. By reducing pathological late sodium entry, ranolazine attenuates the reverse-mode sodium-calcium exchange that drives intracellular calcium overload during ischemia, thereby reducing diastolic wall tension, improving subendocardial perfusion, and preserving myocardial ATP stores without altering systemic hemodynamics.

A secondary electrophysiological action, inhibition of the rapid delayed rectifier potassium current (IKr) with an IC50 of approximately 12 micromolar, produces dose-dependent QTc interval prolongation on the surface electrocardiogram. Paradoxically, the net electrophysiological effect is antiarrhythmic rather than proarrhythmic, because the INaL inhibition shortens the effective action potential duration at the cellular level, suppresses early afterdepolarizations, and reduces beat-to-beat repolarization variability. This composite electrophysiology was demonstrated in the MERLIN-TIMI 36 trial (6,560 patients with non-ST-elevation acute coronary syndrome), which showed significant reductions in ventricular tachycardia, supraventricular tachycardia, and new-onset atrial fibrillation in ranolazine-treated patients compared to placebo, and which generated the antiarrhythmic research program that has since extended to the HARMONY and RAFFAELLO atrial fibrillation trials.

The MERLIN-TIMI 36 trial also identified a glycometabolic effect: ranolazine reduced hemoglobin A1c by approximately 0.30 percentage points at 4 months in the overall cohort and by 0.64 percentage points in diabetic patients, with a 32 percent relative reduction in the incidence of new fasting hyperglycemia in non-diabetic patients. The mechanism is attributed to inhibition of late sodium current in pancreatic alpha cells, reducing glucagon secretion, though direct confirmation of this pathway remains incomplete. Pharmacokinetics are dominated by hepatic CYP3A4 metabolism (70 to 75 percent of clearance), with a plasma elimination half-life of approximately 7 hours, a large volume of distribution (85 to 180 liters), and moderate plasma protein binding (approximately 65 percent to alpha-1-acid glycoprotein). The compound is contraindicated with strong CYP3A4 inhibitors and with hepatic cirrhosis; dose reduction to 500 mg in the published literature is required with moderate CYP3A4 inhibitors.

This monograph reviews the chemistry, synthesis, and stereochemistry of ranolazine; the late sodium current mechanism in molecular and electrophysiological detail; the comprehensive human pharmacokinetic record including CYP3A4 dependence; the clinical evidence base across the chronic stable angina, acute coronary syndrome, atrial fibrillation, heart failure with preserved ejection fraction, pulmonary hypertension, and glycometabolic indications; the reconstitution, sourcing, and stack-interaction considerations for laboratory work; and a comparative assessment of five alternative antianginal or anti-ischemic candidates against ranolazine on five competency standards (novelty, effect size, promising potential, side-effect profile, and overall validation). The compound is a registered medicine in the United States, the European Union, and other jurisdictions. Research-grade ranolazine is widely available from multiple suppliers at greater than 98 percent purity; investigators should obtain analytical confirmation of identity and purity on every lot.