Angina is severe chest pain caused by reduced blood flow to the heart. Antianginal medications encompass a group of drug classes that either reduce the consumption of oxygen in the heart muscle or increase oxygen supply to the myocardium to prevent symptoms of angina. These drug classes include antianginals (ranolazine), beta adrenergic blockers
, calcium channel blockers
, and nitrates.
How do they work?
Angina occurs when the coronary arteries (the heart’s primary source of oxygen) supply insufficient oxygen to the myocardium. This increases the heart’s workload, increasing heart rate, preload (blood volume in the ventricle at the end of diastole), afterload (pressure in the arteries leading from the ventricle), and force of myocardial contractility.
Antianginal drugs relieve angina by decreasing one or more of these four factors. This diagram summarizes how antianginal drugs affect the cardiovascular system.
(Lippincott Williams & Wilkins, 2022)
|Drug Class & Indications
|Antianginal: chronic angina
||The mechanism of action and antianginal effects have not been determined.
|Beta Blockers: moderate to severe angina
|Prevent catecholamines from stimulating B1 adrenergic receptors resulting in a decrease in heart rate, blood pressure, and myocardial contraction.
|Calcium Channel Blockers: effort-induced angina and Printzmetal angina
|Inhibit flow of calcium through muscle cells, dilating coronary arteries, slowing the heart rate, and increasing myocardial oxygen supply. They also dilate the peripheral arteries which decreases systemic vascular resistance (afterload).
|Nitrates: recurrent angina, acute angina, unstable angina
||Isosorbide (dinitrate, mononitrate)
|Dilate veins, arteries, and coronary arteries by relaxing vascular smooth muscle, causing decreased afterload and left ventricular end-diastolic pressure (preload), and increased blood flow through collateral coronary vessels.
Ranolazine use is contraindicated with strong CYP3A inhibitors and inducers
and in patients with clinically significant liver impairment (Facts and Comparisons, 2022).
Beta blockers are contraindicated in patients with greater than a first-degree heart block; cardiogenic shock; decompensated, overt or uncontrolled cardiac failure; bronchial asthma; and sick sinus syndrome (except in patients with a functioning permanent pacemaker) (Facts and Comparisons, 2020).
Calcium channel blockers are contraindicated in patients who are taking beta blockers or who have heart failure with reduced ejection fraction, sick sinus syndrome, and second- or third-degree atrioventricular block.
Nitrates are contraindicated in the following (Kannam & Gersh, 2021):
- Patients who have taken sildenafil or vardenafil within 24 hours or tadalafil withing 48 hours as this may result in severe hypotension.
- Patients with hypertrophic cardiomyopathy in whom nitrates can increase outflow tract obstruction.
- Patients with suspected right ventricular infarction as this may cause hypotension.
For complete information and dosing, please consult each drug’s specific package insert or the Nursing2022 Drug Handbook® + Drug Updates