Flecainide

From Anvita Health Wiki

Contents 1 Introduction 2 Indications 3 Contraindications 4 Dosage 5 Dosage-adjustment-in-renal-failure 6 Pharmacokinetics 7 Monitor 8 Adverse-effects 9 Drug-interactions 10 Laboratory 11 Mechanism-of-action 12 More General Terms 13 Additional Terms 14 Internet Database 15 References

Introduction

• Tradename: Tambocor.

Indications

• supraventricular arrhythmias

• atrial fibrillation
• atrial flutter
• paroxysmal supraventricular tachycardia ( PSVT)

• chemical cardioversion of atrial fibrillation
• prevention & suppression of documented life-threatening ventricular arrhythmias

Contraindications

• pre-existing 2nd or 3rd degree AV block
• right bundle branch block associated with left hemiblock
• cardiogenic shock
• myocardial depression (impaired ventricular function in the setting of coronary artery disease)

• Caution:

• pre-existing sinus node dysfunction
• sick sinus syndrome
• history of congestive heart failure
• new bundle-branch block
• patients with pacemakers
• renal or hepatic impairment
  

• pregnancy category = c
• safety in lactation = -

Dosage

• start 50-100 mg PO BID

• PRN dosing for paraxysmal atrial fibrillation [8]

• max 400 mg/day

• Tabs: 50, 100, 150 mg.

Dosage-adjustment-in-renal-failure

• for creatinine clearance < 20 mL/min, decrease dose by 25-50%

Pharmacokinetics

• metabolized in the liver by cyt P450 2D6
  

• elimination via liver 65 %
• elimination via kidney 35 %
• 1/2life = 7-23 hours
• protein binding = 32-58 %
• elimination by hemodialysis = -

Monitor

• baseline serum K+;

• correct hypokalemia or hyperkalemia prior to administration [9]

• plasma flecainide

• hepatic insufficiency
• heart failure (goal is trough < 0.7 ug/mL)
• creatinine clearance < 35 mL/min/1.75 m2
• concurrent administration of amiodarone (recommended)
• elderly (daily during dose adjustment) [9]

Adverse-effects

• common (> 10%)

• dizziness, visual disturbances ( blurred vision), dyspnea

• less common (1-10%)

• headache, nausea, fatigue, palpitations, chest pain, asthenia, tremor, constipation, edema, fever, abdominal pain, tachycardia, rash, exacerbation of ventricular arrhythmia (5%)

• uncommon (< 1%)

• bradycardia, heart block, increased PR interval, increased QRS duration, congestive heart failure, nervousness, hypoesthesia, paresthesia, alopecia, blood dyscrasia, hepatic dysfunction

• other

• negative inotropic effect
• confusion
• irritability
  
• drug adverse effects of antiarrhythmic agent, Group IC

Drug-interactions

• flecainide increases serum levels of digoxin
• flecainide & propranolol increase each other's serum levels
• amiodarone, cimetidine, smoking, antacids, carbonic anhydrase inhibitors & verapamil increase flecainide levels
• flecainide potentiates AV block of beta blockers & Ca+2 channel blockers
• any pharmaceutical agent that inhibits cyt P450 2D6 may increased levels of flecainide
  
• drug interaction(s) of antiarrhythmic agents in combination with diuretics
• drug interaction(s) of beta-adrenergic receptor antagonists with flecainide

Laboratory

• specimen:

• serum, plasma ( heparin, EDTA)
• collect at trough concentration

• methods: GLC, HPLC, FPIA, fluorometry
• interferences:

• propranol & quinidine interfere with fluorometry

• therapeutic range: 0.2-1.0 ug/mL (trough) [9]

Mechanism-of-action

• suppresses ventricular ectopy & non sustained ventricular tachycardia (variably effective & not routinely indicated because of proarrhythmic effects)
• does not favorably affect survival or sudden death
• increases PR interval > 300 ms
• increases QRS duration > 180 ms
• QTc increases

More General Terms

• antiarrhythmic agent, Group IC

Additional Terms

• cytochrome P450 2D6 (cytochrome P450 2D, cytochrome P450 DB1, debrisoquine-4-hydroxylase, CYP2D6)

Internet Database

PubChem: 3356
PubChem: 41022
PubChem: 3355

References

1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
2. Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (ed), Companion Handbook, McGraw Hill, NY, 1994
3. Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 157
4. Kaiser Permanente Northern California Regional Drug Formulary, 1998
5. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
6. Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed., W.B. Saunders, 1995
7. Prescriber's Letter 13(3): 2006 Cytochrome P450 drug interactions Detail-Document#: [1] (subscription needed) [2]
8. Prescriber's Letter 12(1): 2005 "Pill-in-the-Pocket" Approach to Treating Atrial Fibrillation Detail-Document#: [3] (subscription needed) [4]
9. Prescriber's Letter 17(7): 2010 Recommended Lab Monitoring for Common Medications Detail-Document#: [5] (subscription needed) [6]

flecainide (Tambocor)