propafenone (Rythmol, Baxarytmon)
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Introduction
Tradename: Rythmol.
Indications
- supraventricular arrhythmias
- atrial fibrillation
- atrial flutter
- including Wolff-Parkinson-White (WPW) syndrome
- AV nodal re-entry tachycardia
- auxiliary pathway-mediated tachycardia
- chemical cardioversion of atrial fibrillation
- treatment of life-threatening ventricular arrhythmias
Contraindications
- avoid in patients with impaired ventricular function in the setting of coronary artery disease
Dosage
- start 150 mg PO TID
- max 900-1200 mg/day
- dosage adjustment necessary with renal insufficiency
Tabs: 150, 225, 300 mg.
Pharmacokinetics
- well absorbed form GI tract
- large 1st pass hepatic metabolism, thus oral bio- availability is variable
- metabolism genetically variable; extensive vs slow metabolizers
- time to peak serum concentrations: 2-3 hours
- serum levels do not correlate with clinical response
- 85-95% of drug bound to plasma proteins
- metabolized by cyt P450 2D6
- elimination 1/2life is 5-17 hours, depending upon metabolizer status
elimination via liver
elimination via kidney
Adverse effects
- common (> 10%)
- less common (1-10%)
- disturbance of taste (metallic & bitter), cardiac conduction disturbances, AV block (1st & 2nd degree), palpitations, congestive heart failure, angina, bradycardia headache, blurred vision, loss of balance, dyspnea, anxiety, constipation, diarrhea, nausea/vomiting, anorexia, abdominal pain, dyspepsia, flatulence
- uncommon (< 1%)
- new or worsening arrhythmias (pro-arrhythmic effect), abnormal speech, visual disturbance, nightmares, paresthesias, leukopenia, thrombocytopenia, agranulocytosis, bundle branch block
- cardiac
- exacerbation of ventricular arrhythmia
- prolongation of PR & QRS intervals
- negative inotropic effects
- other
Drug interactions
- propafenone increases serum levels of:
- quinidine, cimetidine & beta blockers increase propafenone levels in extensive metabolizers
- cyclosporine: increased serum levels & decreased renal function
- rifampin decreases propafenone serum levels
- propafenone inhibits cyt P450 2D6
- inhibits its own metabolism
- may increase levels of drugs metabolized by cyt P450 2D6
- any drug that inhibits cyt P450 2D6 may increase levels of propafenone
- drug interaction(s) of antiarrhythmic agents in combination with diuretics
- drug interaction(s) of beta-adrenergic receptor antagonists with propafenone
Mechanism of action
- both type Ic antiarrhythmic & beta-adrenergic antagonist effects
- suppresses complex non-sustained ventricular ectopy
- slows atrial & ventricular conduction velocity without prolonging repolarization
- non-selective beta-blocker
- negative inotropic effects
More general terms
Additional terms
References
- ↑ The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- ↑ Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (ed), Companion Handbook, McGraw Hill, NY, 1994.
- ↑ Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 158
- ↑ Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998 - not on National VA formulary
- ↑ Kaiser Permanente Northern California Regional Drug Formulary, 1998
- ↑ Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
- ↑ Prescriber's Letter 13(3): 2006 Cytochrome P450 drug interactions Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=220233&pb=PRL (subscription needed) http://www.prescribersletter.com