Cibenzoline

BRAND NAMES

• Cibenol 
• Cibenzolin (as a generic in some regions) 
• Cibenzoline Hydrochloride formulations

MECHANISM OF ACTION 

Cibenzoline is a class I antiarrhythmic drug that works primarily by blocking fast sodium channels in cardiac cells, slowing the conduction of electrical impulses through the heart. This action prolongs the refractory period and stabilizes cardiac rhythm, helping to prevent or treat both supraventricular and ventricular arrhythmias, including those resistant to other first-line therapies.

PHARMACOKINETICS

Absorption

Cibenzoline is well absorbed orally, with bioavailability typically around 70–80%. Peak plasma concentrations are usually reached within 1–2 hours after ingestion. Food may slightly delay absorption but does not significantly reduce the extent of absorption.

Distribution

Cibenzoline has a moderate distribution in the body, with a volume of distribution of about 2–3 L/kg and 50–60% plasma protein binding. It concentrates mainly in the heart, liver, and kidneys, ensuring effective antiarrhythmic action, while only minimally crossing the blood-brain barrier.

Metabolism

Cibenzoline is primarily metabolized in the liver by the cytochrome P450 system, especially CYP3A4, into inactive metabolites. This hepatic metabolism helps regulate its plasma levels and contributes to interindividual variability in drug response.

Excretion

Cibenzoline is eliminated mainly through renal excretion, with about 60–70% of the drugexcreted unchanged in urine. A smaller portion is excreted as inactive metabolites. Its elimination half-life is typically 5–12 hours, which can be prolonged in patients with i mpaired kidney function.

PHARMACODYNAMICS

Cibenzoline works by blocking fast sodium channels in the heart, slowing electrical conduction and prolonging the refractory period. This stabilizes cardiac rhythm and helps prevent or treat both supraventricular and ventricular arrhythmias, including cases resistant to other antiarrhythmic drugs.

ADMINISTRATION

Cibenzoline is an antiarrhythmic drug mainly used for the management of certain supraventricular and ventricular arrhythmias. Its administration depends on indication, patient condition, and renal function.

DOSAGE AND STRENGTH

Cibenzoline is usually taken orally, starting at 100 mg three times daily and adjusted according to response, with a typical maximum of 300–400 mg per day. It should be taken after meals, and dose adjustments are needed for patients with kidney or liver impairment. Regular ECG and blood pressure monitoring are recommended to ensure safety and effectiveness.

DRUG INTERACTIONS

• Other antiarrhythmics (e.g., quinidine, flecainide, amiodarone) – may increase risk of arrhythmias or conduction block.

• Beta-blockers or calcium channel blockers – can exacerbate bradycardia or AV block.

• CYP3A4 inhibitors or inducers (e.g., ketoconazole, rifampin) – may increase or decrease plasma levels, altering efficacy or toxicity.

• Drugs prolonging the QT interval – combined use may increase the risk of torsades de pointes.

FOOD INTERACTIONS

Cibenzoline absorption can be slightly delayed by food, but the overall bioavailability is not significantly affected. It is generally recommended to take the drug after meals to reduce gastrointestinal discomfort, but no specific food restrictions are required.

CONTRAINDICATIONS

• Severe heart block or sick sinus syndrome without a pacemaker 

• Severe heart failure or cardiogenic shock 

• Known hypersensitivity to cibenzoline or other class I antiarrhythmics 

• Severe renal or hepatic impairment where drug clearance is dangerously reduced 

• History of proarrhythmic reactions to class I antiarrhythmics

SIDE EFFECTS

• Bradycardia

• Hypotension

• Palpitations

• Conduction disturbances

• Nausea

• Vomiting

• Diarrhea

• Loss of appetite

• Dizziness

• Headache

• Fatigue

• Allergic reactions

• Proarrhythmic effects

OVER DOSE

• Severe bradycardia 

• Heart block 

• Hypotension 

• Ventricular arrhythmias 

• Dizziness 

TOXICITY

Cibenzoline toxicity primarily affects the heart, causing severe bradycardia, heart block, hypotension, and potentially life-threatening arrhythmias. It can also lead to dizziness, confusion, syncope, and gastrointestinal symptoms like nausea and vomiting. Severe cases require supportive care, cardiac monitoring, and sometimes temporary pacing or discontinuation of the drug.