Class Ic

IV DoseNo IV form
Oral dose50-200 mg/m2/day divided q 12 hours Maximum 400 mg/day. Or
6.7-9.5 mg/kg/d divided tid in Japanese study Acta Paediatr Jpn 1994 Feb;36(1):44-8 Improved efficacy with TID dosage in young children and patients with toxicity. Increase in 50 mg/m2 increments every 4 days
Decrease by 50% when used with amiodarone.
LevelsTherapeutic effects at 0.200-1.000 ug/ml.
Increased proarrhythmia and toxicity at > 1.0 ug/ml.
KineticsElimination half-life 7-19 hours (mean 13). in adults, and 7-12 hours (mean 8.7) in children aged 1 month to 13 years.
Reduced clearance in congestive heart failure.
Peak levels at 2-3 hours after oral dose.
CautionsProarrhythmic effect worst in poor LV function. Significant negative inotropic effect.
InteractionsAmiodarone increases levels by 100%.
Additive negative inotropic effect when used with propranolol, verapamil, or disopyramide.
Increases digoxin levels 24% average.
PreparationsTambocor scored tablets: 50, 100 mg.
FDA approval in childrenno