Class: Calcium Channel Blocker
Dosage Forms. Tablet: 40 mg, 80 mg, 120 mg; Tablet, Extended Release: 120 mg, 180 mg, 240 mg; Capsule (Extended Release): 100 mg, 120 mg, 180 mg, 200 mg, 240 mg, 300 mg, 360 mg
Common FDA Label Indication, Dosing, and Titration.
1. Angina: Immediate release, 80-120 mg po tid; Extended release, 180 mg po daily hs, may titrate up to 480 mg po daily
2. Atrial arrhythmia or paroxysmal supraventricular tachycardia: Immediate release, 240-320 mg/d in 3-4 divided doses, may titrate up to 480 mg/d in non-digitalized patients
3. Hypertension: Immediate release, 80 mg po tid; may titrate to 360-480 mg/d; Extended release 180-200 mg po daily, may titrate to 400-480 mg po daily
Off-Label Uses.
1. Migraine headache prophylaxis: 80 mg po tid-qid
MOA. Calcium-channel-blocking drug that prolongs AV nodal conduction. It is used to convert reentrant supraventricular tachycardias and slow ventricular rate in atrial fibrillation or flutter. Because it decreases contractility and arteriolar resistance, it is used in angina caused by coronary obstruction or vasospasm.
Drug Characteristics: Verapamil
Medication Safety Issues: Verapamil
Drug Interactions: Verapamil
Adverse Reactions: Verapamil
Efficacy Monitoring Parameters. Decreased blood pressure, improvement in heart rate and rhythm, reduction of chest pain, decreased number of weekly angina attacks, reduction in use of nitroglycerin for chest pain.
Toxicity Monitoring Parameters. Signs/symptoms of heart failure, decreased heart rate, signs/symptoms of liver toxicity. Exacerbations of angina pectoris or acute coronary insufficiency; while tapering chronic therapy, especially in patients with ischemic heart disease. Monitor LFTs, vital signs.
Key Patient Counseling Points. Do not crush or chew extended-release products. Contents of extended-release capsules may be sprinkled on food and swallowed without chewing, followed by water. Instruct patient to report symptomatic hypotension, bradyarrhythmia, peripheral edema, or syncope. Advise patients against sudden discontinuation of drug, as this may precipitate hypertensive rebound/crisis.
Clinical Pearls. Not approved in children under 18 y of age.