What Is Verapamil and How Does It Work?
Verapamil is indicated to treat hypertension, treat and prevent chest pain (angina), supraventricular arrhythmia and atrial fibrillation/flutter, chronic atrial fibrillation, paroxysmal supraventricular tachycardia, supraventricular tachycardia (pediatric), and tardive dyskinesia.
What Are Side Effects Associated with Using Verapamil?
Side effects associated with the use of Verapamil, include the following:
- Increased liver enzymes
- Low blood pressure (hypotension)
- Shortness of breath
- Sleep disturbance
- Swelling (edema)
- Swollen gums
Other side effects of verapamil reported include:
- Abnormal ECG
- High blood pressure (hypertension)
- Elevated liver function test results
- Weakness or lack of energy
Call your doctor at once if you have the following serious side effects:
- blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
- fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness;
- low levels of sodium in the body with severe headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady; or
- severe nervous system reaction with very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, and feeling like you might pass out.
This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.
What Are Dosages of Verapamil?
Dosages of Verapamil:
Adult and Pediatric Dosage Forms and Strengths
- 2.5 mg/mL
- 40 mg
- 80 mg
- 120 mg
Tablet/capsule, extended release
- 100 mg
- 120 mg
- 180 mg
- 200 mg
- 240 mg
- 300 mg
- 360 mg
Dosage Considerations – Should be Given as Follows:
- Adult, Immediate release: 80 mg orally every 8 hours initially; usual range: 80-120 mg orally every 8 hours; not to exceed 480 mg/day
- Adult, Extended-release: Covera-HS: 180 mg/day orally at bedtime initially; maintenance: 180-540 mg/day orally at bedtime
- Geriatric, Immediate release: 80 mg orally every 8 hours initially; usual range: 80-120 mg orally every 8 hours; not to exceed 480 mg/day
- Geriatric, Extended-release (Covera-HS): 180 mg orally at bedtime initially; maintenance: 180-540 mg orally at bedtime
Adult, Immediate release: 80 mg orally every 8 hours initially; maintenance: 80-320 mg orally every 12 hours
- Calan, Isoptin SR: 180 mg/day orally given in the morning (120 mg/day initially if the patient is elderly or of small stature); for the desired response, may be increased to 240 mg/day, then to 360 mg/day (either 180 mg every 12 hours or 240 mg in the morning and 120 mg in the evening)
- Verelan: 180 mg/day orally (120 mg/day initially if the patient is elderly or of small stature); for the desired response, may be increased to 240 mg/day orally, then by 120 mg/day at weekly intervals; not to exceed 480 mg/day
- Verelan PM: 200 mg/day orally at bedtime (100 mg/day if patient elderly or of small stature); may be increased by 100 mg/day at weekly intervals as needed; not to exceed 400 mg/day
- Covera-HS: 180 mg/day orally at bedtime (120 mg/day initially if the patient is elderly or of small stature); for the desired response, may be increased to 240 mg/day, then by 120 mg/day at weekly intervals; not to exceed 480 mg/day
- Immediate release: 40 mg orally every 8 hours initially; maintenance: 80-320 mg orally every 12 hours
- Extended-release (Calan SR, Isoptin SR, Verelan): 120 mg/day orally given in the morning
- Extended-release (Covera-HS): 180 mg/day orally at bedtime
- Extended-release (Verelan PM): 100 mg/day orally at bedtime
Supraventricular Arrhythmia and Atrial Fibrillation/Flutter
- 2.5-5 mg intravenously (IV) over 2 minutes; 5-10 mg dose may be repeated after 15-30 minutes
- Alternatively, 0.075-0.15 mg/kg (not to exceed 10 mg) IV over 2 minutes; dose may be repeated once 30 minutes after the first dose
Chronic Atrial Fibrillation and Paroxysmal Supraventricular Tachycardia
- Treatment of chronic atrial fibrillation (rate control); prevention of paroxysmal supraventricular tachycardia
- Immediate release: 240-480 mg/day orally divided every 6-8 hours
Supraventricular Tachycardia, Pediatric
- Children 1-15 years old: 0.1-0.3 mg/kg (not to exceed 5 mg) intravenously (IV) over 2 minutes; second dose (not to exceed 10 mg) may be given after 30 minutes
- Alternatively (not well established), 4-8 mg/kg/day orally divided every 8 hours
- 40 mg orally every 8 hours; maybe titrated to 120 mg every 8 hours
- 160-320 mg orally every 6-8 hours
- Renal impairment: Use with caution; monitor ECG; for Verelan PM, the manufacturer recommends 100 mg at bedtime initially; if CrCl is less than 10 mL/min, reduce dose by 25-50%
- Hepatic impairment: In cirrhosis, reduce dose by 20-50% of normal for oral and intravenous (IV) administration
- Geriatric: In general, lower initial doses are warranted; doses should be adjusted on basis of clinical response
What Other Drugs Interact with Verapamil?
If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.
- Severe Interactions of Verapamil Include:
- Verapamil has serious interactions with at least 69 different drugs.
- Verapamil has moderate interactions with at least 282 different drugs.
- Verapamil has mild interactions with at least 129 different drugs.
This information does not contain all possible interactions or adverse effects. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you, and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns, or for more information about this medicine.
What Are Warnings and Precautions for Verapamil?
- This medication contains verapamil
- Do not take Isoptin SR, Calan SR, Covera HS, Isoptin, Isoptin IV, Calan, Verap, Verapamil SR, Verelan, or Verelan PM if you are allergic to verapamil or any ingredients contained in this drug
- Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately
- Hypersensitivity to verapamil or other calcium channel blockers
- Cardiogenic shock
- Congestive heart failure
- Symptomatic hypotension
- Sick sinus syndrome (unless a permanent pacemaker is in place)
- 2°/3° AV block (unless a permanent pacemaker is in place)
Effects of Drug Abuse
- No information provided
- Low blood pressure (hypotension), initially or after dose increases
- Worsening of chest pain (angina) during initiation of treatment, after a dose increase, or after withdrawal of beta-blocker
- See "What Are Side Effects Associated with Using Verapamil?"
- Skin necrosis is reported with use; caution in patients at risk for hemorrhage, necrosis, or gangrene.
- See "What Are Side Effects Associated with Using Verapamil?”
- Aortic stenosis
- Atrial fibrillation/flutter with accessory bypass tract
- 1° AV block
- Hypertrophic cardiomyopathy (e.g., idiopathic hypertrophic subaortic stenosis)
- Hypotension (initially or after dose increases)
- Exacerbation of angina (during initiation of treatment, after a dose increase, or after withdrawal of beta-blocker)
- Neuromuscular transmission defects; may exacerbate myasthenia gravis
- Hepatic or renal impairment
- Persistent progressive dermatologic reactions
- Generic products may not be bioequivalent
- Do not prescribe Covera-HS or Verelan PM for shift workers
- Concurrent beta-blocker therapy
- Concurrent ivabradine therapy
- Slows AV conduction; use cautiously with beta-blockers
- Hypotension and bradyarrhythmias were observed with concurrent use of other CYP3A4 substrates (e.g., cyclosporine, telithromycin) because of competitive metabolism
- Co-administration with CYP3A4 inhibitors (e.g., erythromycin, itraconazole) may decrease metabolism and thus increase toxicity
- Sinus bradycardia resulting in hospitalization and pacemaker insertion has been reported in association with concurrent use of clonidine with verapamil; monitor heart rate if coadministered
- Verapamil is no longer part of the Pediatric Advanced Life Support tachyarrhythmia algorithm
- The potential toxic dose in patients younger than 6 years old: 15 mg/kg
Pregnancy and Lactation
- Use verapamil with caution during pregnancy if the benefits outweigh the risks. Animal studies show risk and human studies are not available, or neither animal nor human studies were done
- Verapamil is distributed in milk; nursing infant doses range from less than 0.01% to 0.1% of the mother's dose. The manufacturer suggests refraining from nursing (though the American Academy of Pediatrics committee states that verapamil is compatible with nursing)
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