Propafenone

INTRODUCTION

Indications

Treatment of life-threatening ventricular arrhythmias, including ventricular tachycardia. Prolongs the time to recurrence of symptomatic paroxysmal atrial arrhythmias, including paroxysmal atrial fibrillation/flutter (PAF) and paroxysmal supraventricular tachycardia (PSVT). Unlabeled Use: Single-dose treatment for atrial fibrillation.

Action

Slows conduction in cardiac tissue by altering transport of ions across cell membranes. Therapeutic Effects: Suppression of ventricular arrhythmias.

Adverse Reactions/Side Effects

CNS: dizziness, shaking, weakness. EENT: blurred vision. CV: SUPRAVENTRICULAR ARRHYTHMIA, VENTRICULAR ARRHYTHMIAS, conduction disturbances, angina, bradycardia, hypotension. GI: altered taste, constipation, nausea, vomiting, diarrhea, dry mouth. Derm: rash. MS: joint pain.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Assess heart rate, ECG, and heart sounds, especially during exercise (See Appendices G, H). Although intended to treat certain arrhythmias, this drug can unmask or precipitate new arrhythmias (proar-rhythmic effect). Report any rhythm disturbances or symptoms of increased arrhythmias, including palpitations, chest pain, shortness of breath, fainting, and fatigue/weakness.

• Assess blood pressure periodically and compare to normal values (See Appendix F). Report low blood pressure (hypotension), especially if patient experiences dizziness or syncope.

• Assess any joint pain to rule out musculoskeletal pathology; that is, try to determine if pain is drug induced rather than caused by anatomic or biomechanical problems.

• Assess dizziness and weakness that might affect gait, balance, and other functional activities (See Appendix C). Report balance problems and functional limitations to the physician, and caution the patient and family/caregivers to guard against falls and trauma.

Interventions

• Because of the risk of CHF and arrhythmias, use extreme caution during aerobic exercise and other forms of therapeutic exercise. Assess exercise tolerance frequently (blood pressure, heart rate, fatigue levels), and terminate exercise immediately if any untoward responses occur (See Appendix L).

Patient/Client-Related Instruction

• Advise patient and family or caregivers about the signs of arrhythmias (see above under Examination and Evaluation) and to seek immediate medical assistance if these signs develop

• Instruct patient and family/caregivers to report other side effects such as severe or prolonged shaking, blurred vision, skin rash, or GI problems (nausea, vomiting, diarrhea, constipation, altered taste, dry mouth).

Pharmacokinetics

Absorption: Although well absorbed following oral administration, undergoes rapid hepatic metabolism (bioavailability 3–11%).

Distribution: Widely distributed; crosses the placenta.

Metabolism and Excretion: Extensively metabolized by the liver (CYP1A2, CYP2D6, and CYP3A4 enzyme systems); some metabolites have antiarrhythmic activity. >90% of patients are considered extensive metabolizers. Others metabolize propafenone more slowly.

Half-life: 2–10 hr in extensive metabolizers; 10–32 hr in ...