Quinidine

Quinidine (Cardioquin, Serecor)

Mechanism of action

• Complex electrophysiological effect that is still not fully understood.
• Blocks the fast inward sodium current, mostly in Purkinje fibres, which slows down its rapid depolarization.
• Also inhibits potassium and L-type calcium channels which leads to prolongation of the action potential duration.

Indications and dose

Pharmacokinetics

Onset of action: 2 hours

Half-life of elimination: 6–8 hours

Metabolism: Hepatic (CYP 3A4)

Elimination: Kidneys (less than 20 % of unchanged drug)

Directions for administration

Patients should not drink grapefruit juice while taking this medication.

ECG monitoring of possible QT interval prolongation should be done when giving quinidine long term. 

Medicinal forms

Pills 

• immediate-release 200 mg, 300 mg 
• extended-release 324 mg

Side-effects

QT prolongation

Arrhythmia (torsades de pointes)

Nausea, vomiting

Fever, chills

Ringing in the ears

Blurred vision

Confusion, weakness

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References‍

1. Quinidine: Uses, Interactions, Mechanism of Action | DrugBank Online
2. Quinidine - StatPearls - NCBI Bookshelf (nih.gov)
3. Quinidine Uses, Side Effects & Warnings - Drugs.com
4. Quinidine: MedlinePlus Drug Information

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