Quinidine
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Drug Status
Government Approvals
US(FDA)
WHO Essential Medicine
NO
Known Teratogen
No
Pharmaceutical Class
Antiarrhythmic and Cytochrome P450 2D6 Inhibitor
Controlled Drug Substance
No
Quinidine
Summary
Quinidine is used to treat and prevent abnormal heart rhythms such as atrial fibrillation and ventricular arrhythmias. It is also used to treat severe cases of malaria caused by the Plasmodium falciparum parasite.
Quinidine works by blocking sodium channels in the heart. This slows down the electrical conduction, helping to stabilize the heartbeat and reduce abnormal heart rhythms. It also has mild antimalarial properties.
For adults, the usual dose for treating atrial fibrillation ranges from 200-400 mg every 6-8 hours. The dose for life-threatening arrhythmias may be higher. Pediatric dosing is based on weight and must be determined by a doctor.
Common side effects of Quinidine include nausea, diarrhea, dizziness, and headache. Serious side effects can include irregular heartbeat, severe allergic reactions, or low blood pressure.
People with severe heart block, myasthenia gravis, or an allergy to Quinidine should avoid it. It should be used cautiously in those with kidney or liver disease. Quinidine can interact with other medications and supplements, so inform your doctor about all medications you take.
Indications and Purpose
How does Quinidine work?
It blocks sodium channels in the heart, slowing electrical conduction and reducing abnormal heart rhythms. It also has mild antimalarial properties, affecting Plasmodium falciparum parasites.
Is Quinidine effective?
Yes, studies show Quinidine effectively restores and maintains normal heart rhythm. It is also highly effective in treating severe malaria. However, its use has declined due to newer, safer antiarrhythmic drugs.
What is Quinidine?
Quinidine is a medication used to treat certain heart rhythm disorders (arrhythmias) by helping the heart maintain a normal rhythm. It belongs to the class of antiarrhythmic drugs and works by blocking sodium channels in the heart, slowing electrical conduction and stabilizing the heartbeat.
Directions for Use
For how long do I take Quinidine?
The duration depends on the condition being treated. It may be used short-term for certain arrhythmias or long-term to prevent recurrence. Your doctor will determine the necessary duration based on your response.
How do I take Quinidine?
Take Quinidine with a full glass of water, with or without food. Swallow extended-release tablets whole—do not crush or chew them. Follow your doctor’s instructions carefully to avoid serious heart complications.
How long does it take for Quinidine to start working?
Quinidine begins affecting heart rhythm within 1–2 hours after taking an immediate-release tablet. However, full stabilization of the heart rhythm may take a few days of regular use.
How should I store Quinidine?
Store at room temperature (20–25°C) in a dry place away from moisture and heat. Keep it in its original container and out of reach of children.
What is the usual dose of Quinidine?
For adults, the usual dose varies based on the condition being treated. For atrial fibrillation, doses range from 200–400 mg every 6–8 hours. For life-threatening arrhythmias, higher doses may be needed. Pediatric dosing is based on weight and must be determined by a doctor.
Warnings and Precautions
Can I take Quinidine with other prescription drugs?
Quinidine interacts with digoxin, warfarin, amiodarone, and certain antibiotics, increasing the risk of serious heart issues. Inform your doctor about all medications you take.
Can Quinidine be taken safely while breastfeeding?
Quinidine passes into breast milk in small amounts. While generally considered safe, monitor the baby for any unusual symptoms like irritability or slow heart rate.
Can Quinidine be taken safely while pregnant?
It is generally not recommended unless absolutely necessary, as it may affect the baby's heart rhythm. Consult your doctor before using Quinidine during pregnancy.
Is it safe to drink alcohol while taking Quinidine?
Alcohol can worsen dizziness, low blood pressure, and irregular heartbeats. It is best to limit or avoid alcohol while on Quinidine.
Is it safe to exercise while taking Quinidine?
Moderate exercise is usually safe, but avoid intense physical activity if you experience dizziness or irregular heartbeats. Always consult your doctor before exercising.
Is Quinidine safe for the elderly?
Elderly patients may be more sensitive to Quinidine’s effects and are at a higher risk of side effects like low blood pressure and dizziness. Dosage adjustments may be needed.
Who should avoid taking Quinidine?
People with severe heart block, torsades de pointes, myasthenia gravis, or quinidine allergy should avoid it. It should be used cautiously in those with kidney or liver disease.
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