Propafenone-Induced Liver Injury

Propafenone hepatotoxicity: report of a new case and review of the literature

Propafenone is a class Ic antiarrhythmic drug. It is a beta-adrenergic blocker that causes bradycardia and bronchospasm. It is metabolized primarily in the liver. Its bioavailability and plasma concentration differ among patients under long-term therapy. They are genetically determined by the hepatic cytochrome P-450 2D6. Hepatic toxicity is highly uncommon. To date, only eight patients were reported in the reviewed world literature. In this article, one new case will be reported emphasizing the importance of medication history taking in patients presenting with new-onset liver enzymes abnormalities.

Bicarbonate therapy for unstable propafenone-induced wide complex tachycardia

A previously healthy 73-year-old woman presented to hospital with acute atrial fibrillation. After intravenous procainamide failed to restore sinus rhythm, she was treated with 300 mg of oral propafenone and discharged with a prescription for propafenone and propranolol. Six hours later she took 150 mg of propafenone as prescribed. Within 1 hour she became dyspneic and collapsed. On arrival in hospital she was unconscious, with a wide complex tachycardia and no obtainable blood pressure. After defibrillation and lidocaine, she converted to a wide complex sinus rhythm, but remained profoundly hypotensive despite intravenous epinephrine and dopamine. Hypertonic sodium bicarbonate (HCO3) was administered and, shortly thereafter, her blood pressure increased, her QRS duration normalized and her clinical status improved dramatically. In this case of severe refractory propafenone-related cardiac toxicity, intravenous HCO3 led to a profound clinical improvement. Emergency physicians should be familiar with the syndrome of sodium-channel blocker poisoning and recognize the potentially important role of bicarbonate in its treatment.

Use of propafenone for conversion of chronic atrial fibrillation in horses

OBJECTIVE

To investigate effects of IV administration of propafenone for naturally occurring and experimentally induced chronic atrial fibrillation in horses.

ANIMALS

2 horses with naturally occurring atrial fibrillation and 4 horses with pacing-induced atrial fibrillation.

PROCEDURES

Horses received a bolus of propafenone (2 mg/kg, IV over 15 minutes). If atrial fibrillation persisted after 20 minutes, a continuous infusion of propafenone (7 microg/kg/min) was given for 120 minutes. Before, during, and after treatment, plasma propafenone concentrations, hematologic and serum biochemical values, and electolyte concentrations analyses were determined and clinical signs were monitored. Surface ECGs were recorded. If propafenone treatment failed, quinidine sulfate was administered.

RESULTS

Bolus and continuous infusion induced minimal adverse effects. During the 15-minute bolus administration, a slight increase in heart rate was observed and horses appeared more sensitive to external stimuli. Throughout treatment, no significant changes were observed in respiratory rate, QRS or corrected QT duration, or results of hematologic analyses. Although a significant increase in F-wave interval and atrial fibrillation cycle length was observed and plasma propafenone concentrations (569 to 1,268 ng/mL) reached the human therapeutic range (64 to 1,044 ng/mL), none of the horses cardioverted to sinus rhythm. Sinus rhythm could be restored in all horses via standard oral administration of quinidine.

CONCLUSIONS AND CLINICAL RELEVANCE

A slow IV bolus of 2 mg of propafenone/kg followed by a continuous infusion of 7 microg/kg/min over 2 hours was not an effective treatment for chronic atrial fibrillation in horses.

Propafenone hepatotoxicity: report of two new cases

Two patients developed acute cholestatic hepatitis during treatment with propafenone. Viral infections, alcohol abuse, hepatotoxicity by other drugs, and biliary obstruction were excluded as causes. In one patient, liver biopsy showed changes consistent with a drug-associated injury. Another patient had autoimmune antibodies (ANA) in the serum. Following propafenone withdrawal, the clinical and biochemical profiles of both patients improved. Hepatic toxicity from the antiarrhythmic drug propafenone is highly uncommon. Moreover, the drug produces hepatocellular injury by an unknown mechanism. Most of the seven cases reported here had acute cholestatic hepatitis after a latency period of two to four weeks.