Other Antianginals
High-yield Verified · Oct 2026The classic antianginals cut oxygen demand by slowing the heart, weakening contraction or unloading it. Ranolazine does none of these: it targets the late sodium current that drives calcium overload in ischemic muscle — which is why it is added to them rather than replacing them.
Nursing view → administration, monitoring and patient teaching
Drugs
Mechanism
Ranolazine has anti-ischemic and antianginal effects that do not depend on reducing heart rate or blood pressure; its exact antianginal mechanism is not established. At therapeutic levels it inhibits the cardiac late sodium current, which in ischemic myocytes lowers intracellular sodium and, through the sodium–calcium exchanger, intracellular calcium, reducing wall tension and oxygen consumption. It also blocks IKr, which prolongs the QT interval.
How the classic antianginals lower oxygen demand
Beta-blockers inhibit the chronotropic and inotropic effects of sympathetic stimulation, so heart rate falls; the negative chronotropic and inotropic effects lower oxygen demand, and blood pressure falls too. Non-dihydropyridine calcium channel blockers (verapamil, diltiazem) inhibit the SA and AV nodes, slowing conduction and contractility and reducing oxygen demand, whereas the dihydropyridines act mainly as peripheral vasodilators with minimal direct myocardial effect.
Nitroglycerin relaxes vascular smooth muscle, mainly veins: pooling blood peripherally lowers venous return and left ventricular end-diastolic pressure (preload). Myocardial oxygen consumption — measured by the pressure-rate product — falls, while heart rate usually rises slightly as a reflex to the fall in blood pressure. Ranolazine is different: its antianginal effect does not depend on lowering heart rate or blood pressure, and it does not change the rate-pressure product at maximal exercise.
The late sodium current and calcium overload
In ischemic cardiac myocytes, ranolazine inhibits the late phase of the inward sodium current. Less sodium accumulates inside the cell, so less calcium enters through the sodium–calcium exchanger; the lower intracellular calcium decreases ventricular wall tension and myocardial oxygen consumption without significantly changing blood pressure or heart rate. The label is cautious — ranolazine inhibits the late sodium current at therapeutic levels, but how that relates to angina relief is not established.
Ranolazine also inhibits fatty acid oxidation, shifting the heart toward glucose oxidation and reducing lactic acid production. In trials, improvements in exercise tolerance were dose- and concentration-dependent and independent of heart rate, blood pressure or background antianginal therapy.
Two channels, one paradox: QT prolongation with little torsades
Ranolazine also inhibits the rapid delayed rectifier potassium current, IKr, which prolongs the ventricular action potential and the QTc in proportion to the plasma level; T-wave amplitude can fall and T waves can notch. Yet its main action — late sodium current inhibition — shortens or barely changes action potential duration at the cellular level, which accounts for the low torsades risk despite QT prolongation.
On 7-day Holter monitoring of 3162 acute coronary syndrome patients, no proarrhythmia was seen, and arrhythmias were less frequent than with placebo (80% versus 87%), though this did not reduce mortality or arrhythmia hospitalization. In long QT syndrome type 3, caused by gain-of-function mutations that increase late sodium current, ranolazine shortens the prolonged QTc.
Comparing the drugs
Antianginals compared
| Drug | Main action | Heart rate | Blood pressure | How O₂ demand falls |
|---|---|---|---|---|
| Ranolazine | Late Na⁺ current inhibition (also IKr block) | Change < 2 bpm | Systolic change < 3 mm Hg | Less Ca²⁺ overload and wall tension; rate-pressure product unchanged |
| Beta-blockers | β-receptor blockade | Lowered | Lowered (↓ renin, ↓ cardiac output) | Negative chronotropy and inotropy |
| Verapamil, diltiazem | L-type Ca²⁺ channel block at SA/AV nodes and myocardium | Slower conduction | Lowered | Slower conduction and contractility |
| Dihydropyridine CCBs | L-type Ca²⁺ channel block in vascular smooth muscle | Minimal direct myocardial effect | Lowered (peripheral vasodilation) | Peripheral vasodilation |
| Nitroglycerin | Vascular smooth-muscle relaxation, veins > arteries | Slight reflex rise | Falls | Lower preload; pressure-rate product falls |
Pharmacokinetics
- Absorption
- Highly variable (steady-state peak 400–6100 ng/mL at the maximum dose); peak at 2–5 hours; bioavailability of the extended-release tablet 76% relative to solution. As a P-gp substrate, its absorption rises with P-gp inhibitors; food has no important effect.
- Distribution
- Protein binding about 62% on the label (about 65%, mainly to α1-acid glycoprotein, in StatPearls); steady-state volume 85–180 L.
- Metabolism
- Extensively metabolized in the gut and liver, mainly by CYP3A and less by CYP2D6; less than 5% is excreted unchanged. Ketoconazole raised levels 220%, diltiazem 50–130%, rifampin cut them about 95%.
- Elimination
- Apparent terminal half-life about 7 hours, steady state within 3 days of twice-daily dosing; about 75% of a dose appears in urine and 25% in feces.
- Effects on other drugs
- Ranolazine and its O-demethyl metabolite weakly inhibit CYP3A and moderately inhibit CYP2D6 and P-gp, and ranolazine inhibits OCT2 — raising simvastatin (100%), digoxin (50%) and metformin (up to 80%) exposure.
- Hepatic and renal impairment
- Peak levels rose 30% (Child-Pugh A) and 80% (Child-Pugh B) in cirrhosis, with a 3-fold greater QT effect; in renal impairment peak levels rose 40–50%. A small creatinine rise reflects blocked tubular creatinine secretion, not reduced GFR.
Uses & drug choice
- Chronic angina — added to beta-blockers, nitrates, calcium channel blockers, antiplatelet, lipid-lowering, ACE-inhibitor or ARB therapy
Adverse effects
- Dizziness, headache, nausea, constipation
- Dose-related — dizziness may increase with dose, and doses above 1000 mg twice daily are poorly tolerated.
- QT prolongation
- IKr block prolongs the ventricular action potential; the QTc rises linearly with plasma level, so anything raising the level (CYP3A inhibitors, cirrhosis) increases it.
- Acute renal failure in severe renal impairment
- Reported with creatinine clearance below 30 mL/min; distinct from the benign ~0.1 mg/dL creatinine rise caused by inhibition of tubular creatinine secretion, which comes without a BUN change and reverses on stopping.
- Neurologic toxicity (tremor, myoclonus, incoordination)
- Exposure-driven — events often followed a dose increase or higher exposure and many resolved after stopping or reducing the dose.
Toxicity & antidote
Overdose has caused hypotension, QT prolongation, bradycardia, myoclonus, severe tremor, unsteady gait, dizziness, vomiting and hallucinations; high intravenous exposure caused diplopia, paresthesia, confusion and syncope, and extreme overdoses have been fatal.
There is no antidote: care is supportive with continuous ECG monitoring, and because ranolazine is about 62% protein-bound, hemodialysis is unlikely to clear it.
Interactions
Contraindications
- Strong CYP3A inhibitors (e.g., ketoconazole, itraconazole, clarithromycin, nefazodone, ritonavir, nelfinavir) — They raise ranolazine levels sharply (ketoconazole by about 220%), increasing QT prolongation and toxicity.
- CYP3A inducers (e.g., rifampin, rifabutin, phenobarbital, phenytoin, carbamazepine, St. John’s wort) — They lower ranolazine levels drastically (rifampin by about 95%).
- Liver cirrhosis — Drug levels rise, and QT prolongation was about 3-fold greater in cirrhotic patients.
- Known QT prolongation, congenital long QT syndrome or a family history of it, or other QT-prolonging drugs use caution — Ranolazine prolongs the QTc, and there is little experience in these patients.
- Severe renal impairment (creatinine clearance < 30 mL/min) use caution — Acute renal failure has occurred; renal function is monitored when creatinine clearance is below 60 mL/min.
High-yield
- Rate — heart rate changes by less than 2 bpm
- And Numbers — systolic pressure changes by less than 3 mm Hg; the rate-pressure product is unchanged
- The work is done inside the myocyte: late Na⁺ current ↓ → Ca²⁺ overload ↓ → wall tension ↓
- Strong CYP3A inhibitors (level up about 220%)
- CYP3A inducers (level down about 95%)
- Cirrhosis (3-fold greater QT effect)
Practice questions
Q1A 68-year-old man with chronic stable angina takes metoprolol, amlodipine and isosorbide mononitrate. His resting heart rate is 54 bpm and blood pressure 102/64 mm Hg, yet he still has exertional angina. A drug is added that improves his exercise tolerance without changing his heart rate or blood pressure.
Which mechanism best explains the added drug’s antianginal effect?
- A.Blockade of β1 receptors in the SA node
- B.Inhibition of the late sodium current, reducing calcium overload in ischemic myocytes
- C.Venodilation that reduces preload
- D.Blockade of L-type calcium channels in vascular smooth muscle
- E.Opening of ATP-sensitive potassium channels
Show answer
B. Inhibition of the late sodium current, reducing calcium overload in ischemic myocytes — Ranolazine inhibits the late inward sodium current in ischemic myocytes, lowering intracellular sodium and calcium influx through the Na⁺–Ca²⁺ exchanger, which reduces wall tension and oxygen consumption without significantly affecting heart rate or blood pressure. Beta-blockers, calcium channel blockers and nitrates lower oxygen demand by slowing the heart, reducing contractility or dilating vessels, and this patient’s heart rate and blood pressure are already low.
Q2A 60-year-old woman on ranolazine for chronic angina develops a respiratory infection and is prescribed clarithromycin. Two days later she reports palpitations and lightheadedness; her QTc has lengthened compared with baseline.
What is the most likely explanation?
- A.Clarithromycin, a strong CYP3A inhibitor, raised ranolazine levels and its IKr-mediated QT effect
- B.Ranolazine inhibits clarithromycin metabolism through OCT2
- C.Infection-related hypokalemia alone
- D.Ranolazine causes torsades independent of its plasma level
- E.Clarithromycin induces CYP3A, lowering ranolazine levels
Show answer
A. Clarithromycin, a strong CYP3A inhibitor, raised ranolazine levels and its IKr-mediated QT effect — Ranolazine is metabolized mainly by CYP3A; strong CYP3A inhibitors such as clarithromycin are contraindicated (ketoconazole raised ranolazine levels by 220%). The QTc rises linearly with ranolazine plasma concentration because of IKr block. Clarithromycin is an inhibitor, not an inducer, and ranolazine’s OCT2 inhibition affects drugs such as metformin.
Q3A 14-year-old with recurrent syncope is found to have long QT syndrome type 3, caused by a gain-of-function mutation in the cardiac sodium channel.
Why might ranolazine shorten his QTc even though it prolongs the QT interval in other patients?
- A.It activates IKr
- B.It raises heart rate, which shortens the QT
- C.It is a β1 antagonist
- D.It inhibits the excess late sodium current that prolongs the action potential in LQT3
- E.It blocks L-type calcium channels in the AV node
Show answer
D. It inhibits the excess late sodium current that prolongs the action potential in LQT3 — Long QT syndrome type 3 results from gain-of-function mutations that increase late inward sodium current. Ranolazine inhibits that current, shortening the abnormally prolonged QTc; in other patients its IKr block is what prolongs the QT, while late sodium inhibition shortens or barely changes action potential duration. Beta-blockers slow the heart and non-dihydropyridine calcium-channel blockers inhibit the SA and AV nodes, but ranolazine’s antianginal effects do not depend on lowering heart rate or blood pressure — mean heart rate changes by less than 2 bpm and systolic pressure by less than 3 mm Hg — so neither nodal block nor a faster rate explains the shorter QTc.
Q4A 72-year-old man starts ranolazine. At 2 weeks his creatinine has risen from 1.0 to 1.1 mg/dL; BUN and potassium are unchanged, and his creatinine clearance is 75 mL/min.
What best explains the change?
- A.Acute tubular necrosis
- B.Reduced glomerular filtration from afferent constriction
- C.Volume depletion
- D.Rhabdomyolysis
- E.Inhibition of tubular creatinine secretion — benign and reversible
Show answer
E. Inhibition of tubular creatinine secretion — benign and reversible — Ranolazine raises serum creatinine by about 0.1 mg/dL regardless of renal function, likely by inhibiting tubular creatinine secretion; the rise is rapid, does not progress, reverses on stopping and is not accompanied by a change in BUN, and ranolazine had no effect on glomerular filtration rate in healthy volunteers. A marked, progressive rise with rising BUN or potassium would instead suggest acute renal failure, reported in severe renal impairment.
Sources
- Ranolazine extended-release tablets (Zydus) — FDA label: contraindications, QT prolongation, renal failure, interactions — FDA / DailyMed
- Ranolazine — late sodium current, calcium overload, monitoring — StatPearls (NCBI)
- Beta Blockers — negative chronotropy and inotropy lower oxygen demand — StatPearls (NCBI)
- Calcium Channel Blockers — non-dihydropyridine nodal effects; dihydropyridine vasodilation — StatPearls (NCBI)
- Nitrostat (nitroglycerin) — venodilation, preload, pressure-rate product (FDA label) — FDA / DailyMed
By LearnDrugs
Educational summary for medical students. Always verify against current prescribing information and guidelines. Not medical advice.