Quinidine: Warnings, Indications, Side Effects, Interactions, Administration and Clinical Monitoring

It is used to treat and prevent irregular heartbeat.

Quinidine sulfate can also be used to treat malaria .

Quinidine oral tablet is only available as a generic drug. There is no branded version available.

Quinidine comes as an immediate-release oral tablet, an extended-release oral tablet, and an injectable solution.

Important warnings

Quinidine can increase the risk of death. Your risk may be higher if you have structural heart disease. Two analyzes of evidence from studies showed that people who took quinidine to prevent irregular heartbeats had a higher risk of dying than those who did not take the drug.

Other warnings

Irregular heart rate warning : Quinidine can cause a serious type of irregular heartbeat called torsade de pointes. This can be fatal.

Sick sinus syndrome warning: If you have sick sinus syndrome, quinidine can cause a very low heart rate.

Risk of other conditions: Quinidine cannot be used in people who have myasthenia gravis, complete atrioventricular blocks in the heart, or a junctional or idioventricular pacemaker. Quinidine is also not safe for you if your doctor has told you that an anticholinergic drug would not be safe.

Quinidine is a drug that only your doctor prescribes. It comes as an oral tablet, an oral extended-release tablet, and an injectable solution.

When quinidine tablets are used to treat malaria, they are used after initial treatment with quinidine gluconate injection.

Indications

Quinidine is used to help treat and prevent atrial fibrillation or flutter and ventricular arrhythmias, types of irregular heart rate. It is used only after other medications have been tried, but it did not work to treat the condition. Quinidine sulfate is also used to treat malaria.

When you first start taking quinidine or increase your dose, you will be monitored in a hospital or clinic. This is done so that your heart rate and heart function can be seen continuously.

How does it work?

Quinidine is a class 1a antiarrhythmic. It works in the heart to slow down the electrical impulses that cause the heart muscle to contract and pump blood. During an arrhythmia, the contractions of the heart muscle are irregular. Decreasing electrical impulses can regulate your heartbeat and stop arrhythmia.

Malaria is caused by a parasite. Quinidine works to treat malaria by preventing the parasite from growing.

Quinidine side effects

Common

The most common side effects that occur with quinidine include:

  • Diarrhea.
  • Stomachache.
  • Daze.
  • Headache.
  • Fatigue.
  • Feel your heart beat faster.
  • Chest pain.
  • Dizziness.
  • Acne.
  • Blurred or double vision

If these effects are mild, they can go away in a few days to a couple of weeks. If they are more severe or do not go away, talk to your doctor or pharmacist.

Serious side effects

Serious side effects and their symptoms may include the following:

  • Liver damage: Symptoms may include yellowing of your skin or the whites of your eyes.
  • Low blood pressure – Symptoms may include dizziness, feeling faint, shortness of breath.
  • Autoimmune or inflammatory problems: Symptoms can include shortness of breath, seizures, fever, itching, rashes, inflammation, and muscle pain.
  • Cinchonism syndrome: This is more likely to occur if you use quinidine long-term and have toxicity. Symptoms can include ringing in your ears, hearing loss, feeling like you are moving when you are not (vertigo), blurred or double vision, and confusion.
  • Disorders of your blood cells (blood dyscrasias): Symptoms may include fatigue, weakness, bruising, and bleeding.
  • Skin reactions

Interactions with other medications

Arrhythmia medications

Taking amiodarone with quinidine can increase the amount of quinidine in your body. This can lead to more side effects and toxicity.

Taking other arrhythmia medications with quinidine can increase the amount of these medications in your body. This can lead to more side effects and toxicity. Examples of these medications include:

  • Digoxin.
  • Mexiletine.
  • Procainamida.

Antacids

Taking these drugs with quinidine can increase the amount of quinidine in your body. This can lead to more side effects and toxicity. Examples of these medications include:

  • Baking soda (Alka-Seltzer).
  • Cimetidine.

Antifungal medication

Taking ketoconazole with quinidine can increase the amount of quinidine in your body. This can lead to more side effects.

Medications for high blood pressure

Taking these drugs with quinidine can decrease the amount of quinidine in your body. This means that it may not work to treat your condition. Examples of these medications include:

  • Nifedipine.
  • Thiazide diuretics.
  • Propranolol.
  • Diltiazem.
  • Verapamil .

Anticonvulsant medications

Taking these drugs with quinidine can decrease the amount of quinidine in your body. This means that it may not work to treat your condition. Examples of these medications include:

  • Phenobarbital.
  • Phenytoin

Antibiotic

Taking rifampin with quinidine can decrease the amount of quinidine in your body. This means that it may not work to treat your condition.

Blood thinner

Taking warfarin with quinidine can increase the amount of warfarin in your body. This means that it may have more side effects.

Medications for depression

Taking certain depression medications with quinidine can increase the amount of these medications in your body. This means that it may have more side effects. Examples of these medications include:

  • Doxepina.
  • Amitriptilina.
  • Imipramina.
  • Desipramina.

Antipsychotic medications

Taking certain antipsychotic medications with quinidine can increase the amount of these medications in your body. This means that it may have more side effects. Examples of these medications include:

  • Haloperidol.
  • Phenothiazines

Pain medication

Taking certain pain relievers with quinidine can decrease the amount of these medications in your body. This means that they may not work to treat your pain. Examples of these medications include:

  • Codeine.
  • Hydrocodone.

Other precautions

Keep this medicine out of the reach of children. Taking the medicine accidentally can be fatal.

Drug Contact: Do not share this drug with others, even if they have the same medical condition. It can affect them significantly.

Management

All possible dosages and forms may not be included here. Your dose, form, and how often you take it will depend on:

  • Your age.
  • The condition being treated.
  • How serious is your condition.
  • Other medical conditions you have.
  • How you react to the first dose.

Dosage to prevent and treat atrial fibrillation

  • Generic: Quinidine Sulfate.

Form: immediate release oral tablet.

Strengths: 200 mg and 300 mg.

Form : extended-release oral tablet.

Strength : 300 mg.

  • Generic: Quinidine gluconate.

Form: extended-release oral tablet.

Strength : 324 mg.

Dosage for adults (over 18 years)

Quinidine Sulfate Oral Tablet

Irregular heart rate treatment: There is no optimal dose for quinidine in treating irregular heart rates. You will likely start with a dose given 3 or 4 times a day. Your doctor will increase your dose as needed to achieve a normal heart rhythm.

Prevention of irregular heart rate and treatment of irregular heart rate in the ventricles: The typical dose is 200 mg taken every 6 hours. Your doctor may increase your dose. The quinidine levels in your blood can be controlled.

Prolonged-release tablet quinidine sulfate

Treatment of irregular heart rate: typical dose is 300-600 mg every 8-12 hours. Your doctor may increase your dose after 4-5 doses.

Prevention of irregular heart rate and treatment of irregular heart rate in the ventricles: The typical dose is 300 mg taken every 8-12 hours. Your doctor may increase your dose.

Quinidine gluconate extended-release oral tablet

Irregular heart rate treatment: There is no optimal dose for quinidine in treating irregular heart rates. You will likely start with a dose given 3 times a day.

Your doctor will increase your dose as needed to achieve a normal heart rate and rhythm. As your dose is adjusted, your heart rate may increase. This does not mean that quinidine is not working.

Child dosage (ages 0-17 years)

The safety and efficacy of using quinidine for atrial fibrillation in people younger than 18 years have not been established.

Dosage for malaria

Generic: Quinidine Sulfate.

Form: immediate release oral tablet.

Strengths: 200 mg and 300 mg.

For adult dosage (over 18 years):

When quinidine tablets are used to treat malaria, they are used after receiving the initial treatment with quinidine gluconate injection. Your doctor can inform you of the dosage information.

For the dose in children and adolescents (ages 0-17 years):

The dose is based on your child’s age and weight.

Special dosing considerations

For people with liver problems: If you have liver problems, your doctor may decrease the dose of quinidine.

For people with heart problems : If you have heart failure, your doctor may lower the dose of quinidine.

Dosing warnings

When you first start taking quinidine or increase your dose, you will be seen in a hospital or clinic. This is done so that your heart rate and heart function can be continuously monitored with EKGs. This is important if you have heart disease or other risk factors for quinidine toxicity.

If your heart rate becomes too high or too low, or if your blood pressure is too low, you can stop your quinidine treatment.

Take as directed

Quinidine is used for the long-term treatment or prevention of heart rate problems. It is a short-term drug treatment for malaria. It includes serious risks if you don’t take it as prescribed.

If you don’t take it all the way on schedule, or suddenly stop taking it, your irregular heartbeat could worsen and cause fatal side effects.

Taking too much increases the risk of dangerous side effects, such as arrhythmias or liver damage.

What to do if you miss a dose : Take it as soon as you remember. If it is only a few hours before the time for your next dose, take only one dose at that time.

Never try to catch up by taking two doses at the same time. This could lead to toxic side effects.

How to tell if the medicine is working: Your heart rate should return to normal or it should take longer for your irregular heart rate to return. Your doctor will monitor your heart rate and heart function.

If you are taking this medicine for malaria, your doctor will tell you if it is working.

Important Considerations for Taking Quinidine

Keep these considerations in mind if your doctor prescribes quinidine for you:

General

  • Quinidine can be taken with food to avoid an upset stomach.
  • You can crush or cut quinidine sulfate tablets.
  • You can cut quinidine sulfate extended release tablets. You can also cut quinidine gluconate extended release tablets.
  • You cannot crush or chew quinidine sulfate or quinidine gluconate extended-release tablets.

Storage

  • Store quinidine at room temperature between 68 ° F and 77 ° F (20 ° C and 25 ° C).
  • Store quinidine out of light and high temperature.
  • Do not store this medicine in humid areas, such as bathrooms.

Clinical monitoring

When you take quinidine, your doctor will check the following to make sure you are taking the correct dose and that the medicine is working:

  • Kidney function.
  • Liver function
  • Heart function, including your blood pressure and heart rate.

They may do tests for side effects that affect blood cells and electrocardiograms (tests that show how well your heart is working).

Is there an alternative?

There are a number of helpful medications to treat your condition. Some may be tighter for you than others. Talk to your doctor about possible options.