encainide (Enkaid)

Pharmacokinetics: 1) metabolized by liver to 2 major metabolites a) O-demethylencaide (ODE) -> therapeutic level: 100-300 ng/mL b) 3-methoxy-O-demethylencaide (MODE) -> therapeutic level: 60-280 ng/mL 2) t1/2 1.2-3.4 hours 3) 7-9% of population are poor metabolizers -> t1/2 increases to 9 hours Adverse effects: 1) hypotension 2) bradycardia 3) seizures 4) chest pain 5) ventricular arrhythmias Drug interactions: -> cimetidine may increase encainide levels Laboratory: 1) specimen: serum, plasma (EDTA, heparin) 2) methods: RIA, HPLC 3) interferences: up to 18% cross-reactivity with N-demethyl metabolite with RIA Mechanism of action: Class Ic antiarrhythmic agent

Interactions

drug interactions drug adverse effects of antiarrhythmic agent, Group IC

Properties

MISC-INFO: elimination route LIVER 1/2life 1.2-3.4 HOURS therapeutic-range 1-400 NG/ML protein-binding 70-78%

References

Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed., W.B. Saunders, 1995