How Pacerone Works and How It’s Taken

Pacerone is a type of antiarrhythmic medicine. It affects electrical signals in the heart by blocking sodium, potassium, and calcium channels. These effects can slow electrical activity and help control certain dangerous heart rhythms.

Doctors prescribe Pacerone when adults have repeated, life-threatening rhythm problems in the heart’s lower chambers. These include ventricular fibrillation, when the lower chambers quiver instead of pumping blood, and hemodynamically unstable ventricular tachycardia, when the lower chambers beat dangerously fast and the heart cannot pump enough blood. Pacerone is used when other heart rhythm medicines have not worked or cannot be tolerated.

Pacerone is taken by mouth as a tablet. Take it the same way each time, either with or without food. Treatment with Pacerone should begin under hospital or specialist supervision in a setting with continuous electrocardiogram monitoring and cardiac-resuscitation capabilities.

Typical Dosing for Life-Threatening Ventricular Arrhythmias

The recommended starting dose of Pacerone is 800 to 1,600 milligrams per day until an initial response occurs, usually within one to three weeks.

Once the heart rhythm is controlled, or if side effects become more noticeable, the dose is lowered to 600 to 800 milligrams per day for one month. The maintenance dose is usually 400 milligrams per day.

The dose must be adjusted for each person.

This information is based on prescribing information, but your healthcare provider may tailor your treatment plan. Always follow their guidance.

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Pacerone Side Effects

Common side effects of Pacerone include:

• Pulmonary inflammation or fibrosis (lung inflammation or scarring)
• Cardiac arrhythmias, including ventricular tachycardia and sinus node dysfunction
• Congestive heart failure
• Hypothyroidism or hyperthyroidism (an underactive or overactive thyroid)
• Nausea or vomiting
• Constipation, decreased appetite, or abdominal pain
• Photosensitivity (sensitivity to sunlight)
• Malaise or fatigue, tremor or other abnormal involuntary movements, dizziness, paresthesia (tingling or numbness), or trouble with coordination or walking
• Decreased libido, insomnia, headache, or other sleep disturbances
• Visual disturbances (vision changes)
• Abnormal liver-function tests or other nonspecific liver problems
• Flushing, abnormal taste or smell, edema (swelling), abnormal salivation, or coagulation abnormalities (blood-clotting problems)

Serious Side Effects and Warnings

Pacerone can cause serious side effects that may require immediate medical attention. These include:

• Pulmonary toxicity — Serious lung inflammation or scarring can cause cough, shortness of breath, chest pain, fever, or coughing up blood.
• Hepatic injury — This can be life-threatening and may cause dark urine, severe tiredness, yellowing of the skin or eyes, nausea or vomiting, or pain in the upper-right abdomen.
• Worsened ventricular arrhythmias — These can include Torsade de Pointes, a dangerous fast heart rhythm associated with QT prolongation that can cause fainting.
• Bradycardia — A slow heart rate or sinus arrest can cause dizziness, lightheadedness, or fainting.
• Optic neuropathy or optic neuritis — These serious eye problems can cause vision loss that may be permanent.
• Thyroid abnormalities — Hyperthyroidism or hypothyroidism can cause weight changes, heat or cold intolerance, restlessness, or unusual fatigue.
• Severe allergic reactions — Anaphylaxis or angioedema can cause swelling of the face or throat, trouble breathing, or shock.

Get medical help right away if you think you are having a serious reaction.

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What To Know Before Taking Pacerone

Before starting Pacerone, your doctor will order:

• A chest X-ray and lung-function tests
• Thyroid blood tests
• Liver blood tests
• Blood tests for potassium, magnesium, and calcium

Low potassium, magnesium, or calcium levels should be corrected before treatment starts.

Tell your doctor about all medicines you take, including prescription drugs, over-the-counter medicines, vitamins, and herbal supplements.

Before taking Pacerone, tell your healthcare provider if you:

• Have lung or breathing problems
• Have liver problems
• Have or had thyroid problems
• Have a slow heart rate or blood pressure problems
• Have ongoing diarrhea
• Have an implanted pacemaker or defibrillator
• Plan to have surgery with general anesthesia

Do not drink grapefruit juice while taking Pacerone. It may increase the amount of Pacerone in your blood and raise the risk of side effects.

Pacerone can make your skin more sensitive to sunlight. Use sunscreen and wear a hat and protective clothing when outdoors. Contact your healthcare provider if you get a severe sunburn.

Do not take Pacerone if you:

• Have cardiogenic shock
• Have sick sinus syndrome
• Have second- or third-degree atrioventricular block
• Have bradycardia that has caused fainting and do not have a functioning pacemaker
• Are allergic to amiodarone, iodine, or any other ingredient in Pacerone

If you miss a dose, wait and take your next dose at the regular time. Do not take two doses at the same time. Continue with your normal dosing schedule.

Tell your doctor if you are pregnant, plan to become pregnant, or become pregnant during treatment. Pacerone may harm your baby if you are pregnant and can remain in your body for months after treatment stops.

Breastfeeding is not recommended during treatment with Pacerone.

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Community FAQs

These answers are fact-checked by our editorial staff.

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Learn More

On MyHeartDiseaseTeam, people share their experiences with heart disease, get advice, and find support from others who understand.

Learn more about Pacerone and heart disease care:

• Pacerone — Upsher-Smith Laboratories
• 3 Treatment Options for Atrial Fibrillation — MyHeartDiseaseTeam
• HCM and Arrhythmias: Risks and Treatment Options — MyHeartDiseaseTeam
• Heart Disease Treatments: Congenital, Heart Valve, and More — MyHeartDiseaseTeam
• What Is an Arrhythmia? — American Heart Association

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