Flecainide

Flecainide, an antiarrhythmic medication used to treat persistent ventricular tachycardia and paroxysmal supraventricular tachycardia, was approved by the US Food and Drug Administration on October 31, 1985. It works by inhibiting certain electrical signals in the heart that might cause an irregular heartbeat. It can also be used to prevent irregular heartbeats such as atrial fibrillation. This can reduce the likelihood of blood clots, excessively rapid heartbeats, heart attacks, and stroke.

BRAND NAME:

Tambocor: It consists of Flecainide acetate as the main active ingredient with the strengths of 50mg,100mg, and 150mg as oral tablets help in treating life-threatening heartbeats.

MECHANISM OF ACTION:

Flecainide is a rapid inward sodium channel with a strong affinity for activated or open sodium channels. Because of its sluggish release from binding, it prolongs depolarization and increases refractoriness while also having a strong effect on the His-Purkinje system, which is responsible for fast electric conduction in the ventricles. It also functions by blocking IKr channels, which delays potassium rectifier current and so prolongs action potential duration in both ventricular and arteriolar muscle fibers. It has been demonstrated to inhibit ryanodine receptor opening and reduce calcium release from the sarcoplasmic reticulum following depolarisation and induced activity.

PHARMACOKINETICS:

Absorption: Flecainide has a bioavailability of 85-90% and is absorbed fully from the gastrointestinal system. It takes 1–3 hours to achieve peak serum concentration.

Distribution: The apparent volume of distribution is approximately 40% of the medication was bound to plasma proteins.

Metabolism: It is metabolised in the liver by cytochromes (CYP2D6 and CYP1A2).

 Excretion: About 30% of orally administered drugs are excreted through urine unchanged.

PHARMACODYNAMICS:

It works by blocking the inward sodium channel Nav 1.5 in a rate- and voltage-dependent manner, reducing the rise of phase 0 of the action potential, especially in His-Purkinje tissue and ventricular muscle. It has a long duration of action, allowing for once-daily dosing.

DOSAGE AND STRENGTH:

The available dosage form of flecainide is 50mg,100mg, and 150mg. It is generally in the form of a tablet. And take once every 2 hours. If the patient takes flecainide once every 8 hours, they experience some side effects. It should be taken at regular time intervals every day. 

Patients with paroxysmal atrial fibrillation and supraventricular tachycardia can be administered dosage starting from 50 mg. The dosage should be taken daily and divided into 8 to 12-hour intervals. Starting with 50 mg orally every 12 hours and then increasing the drug dosage.

For Ventricular arrhythmia prophylaxis dosage can be administered starting from 100 to 400mg daily by mouth and divided into 12-hour intervals. Start with 100 mg for every 12 hours and increase the dose by 100 mg per day for every four hours. The maximum dose is 400 mg daily.

Flecainide may control your condition, but it will not cure it. Suddenly stopping flecainide makes the condition worsen. If you miss a dose, take it as soon as you remember within six hours.

CONTRAINDICATIONS:

Flecainide is contraindicated in patients with structural heart disease, including hypersensitivity, sinus syndrome, cardiogenic shock, and AV block.

DRUG INTERACTIONS:

If the patient is taking some other treatment or medication, they should need to check a few drugs with flecainide.

• Acetazolamide is used to treat altitude sickness, glaucoma, and other conditions.

• Fluconazole is used in treating some antifungal diseases.

• Ritonavir and tipranavir are used in the treatment of HIV.

• Antiseizure medications, including phenytoin and phenobarbital.

• Medicines are used in reducing blood pressure.

• Antibiotics such as erythromycin, and antiarrhythmic medications.

• Cimetidine is used in the treatment of Cimetidine.

FOOD INTERACTIONS:

Absorption is unaffected by food. So it can be administered with or without food.

ADVERSE EFFECTS:

• Constipation

• Stomach pain

• Dizziness

• Changes in vision

• Nausea

• Extreme tiredness

• Confusion

• Shortness of breath

• Bleeding and bruising

• Cough with blood

• Headache

• Chest pain

• Tremors

• Yellowish skin or eyes

• Swelling of hands, legs, and ankles

OVERDOSE:

• Symptoms of overdose may include

• Seizures

• Loss consciousness

• Sudden death

• Irregular heartbeat

• Dizziness

TOXICITY:

Severe toxicity due to flecainide has been reported to cause mortality of 22.5%. By depending on the ECG pattern, we can recognize the toxicity of flecainide.

STORAGE:

Store the drug in a firmly sealed container at room temperature, away from heat and moisture.