Classifications: antiarrhythmic, class ib; Therapeutic: antiarrhythmic, class ib
Pregnancy Category: C
150 mg, 200 mg, 250 mg capsules
Analog of lidocaine with class IB electrophysiologic properties similar to those of procainamide. Shortens action potential
refractory period duration and improves resting potential. Has little or no effect on atrial tissue and produces modest suppression
of sinus node automatically and AV nodal conduction. Prolongs the His-to-ventricular interval (HQ) only if patient has preexisting
Has antiarrhythmic properties for ventricular disturbances.
Acute and chronic ventricular arrhythmias; prevention of recurrent cardiac arrests; suppression of PVCs due to ventricular
Wolff-Parkinson-White syndrome and supraventricular arrhythmias.
Severe left ventricular failure, cardiogenic shock, severe bradyarrhythmias. Preexisting second- or third-degree heart block;
cardiogenic shock; pregnancy (category C); concurrent administration of drugs which alter urinary pH.
Patients with sinus node conduction irregularities, intraventricular conduction abnormalities; hypotension; severe congestive
heart failure; renal failure; liver dysfunction.
Route & Dosage
Adult: PO 200300 mg q8h (max: 1200 mg/d)
Child: PO 1.45 mg/kg q8h
- Give with food or milk to reduce gastric distress.
Adverse Effects (≥1%)CNS: Dizziness, tremor, nervousness, incoordination,
headache, blurred vision, paresthesias, numbness. CV: Exacerbated arrhythmias,
palpitations, chest pain, syncope, hypotension. GI: Nausea, vomiting, heartburn, diarrhea
, dry mouth, abdominal pain. Skin:
Rash. Body as a Whole: Dyspnea
, edema, arthralgia
, fever, malaise
, hiccups. Urogenital:
Impotence, urinary retention.
InteractionsDrug: Phenytoin, phenobarbital, rifampin
may decrease mexiletine levels; cimetidine, fluvoxamine
may increase mexiletine levels; may increase theophylline
levels; may increase proarrhythmic effects of dofetilide
by at least 1 wk).
Readily from GI tract. Peak:
23 h. Distribution:
Distributed into breast milk. Metabolism:
In liver. Elimination:
In urine; renal
elimination increases with urinary acidification. Half-Life:
Assessment & Drug Effects
- Check pulse and BP before administration; make sure both are stabilized.
- Effective serum concentration range is 0.52 mcg/mL.
- Lab tests: Baseline and periodic liver function tests.
- Supervise ambulation in the weak, debilitated patient or the older adult during drug stabilization period. CNS adverse reactions
predominate (e.g., intention tremors, nystagmus, blurred vision, dizziness, ataxia, confusion, nausea).
- Encourage drug compliance; affected particularly by the distressing adverse effects of tremor, ataxia, and eye symptoms.
- Check frequently with patient about adherence to drug regimen. If adverse effects are increasing, consult physician. Dose
adjustment or discontinuation may be needed.
Patient & Family Education
- Learn about pulse parameters to be reported: Changes in rhythm and rate (bradycardia = pulse below 60); symptomatic bradycardia
(light-headedness, syncope, dizziness), and postural hypotension.