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mexiletine
generic
Black Box Warnings .
Increased Mortality
excessive mortality or nonfatal cardiac arrest rate (7.7% encainide/flecainide vs. 3% placebo) in asymptomatic non-life-threatening ventricular arrhythmias with MI 6 days - 2 years prior; restrict use to life-threatening ventricular arrhythmias, no survival benefit in patients without life-threatening arrhythmias
Adult Dosing .
Dosage forms: CAP: 150 mg, 200 mg, 250 mg
ventricular arrhythmias
- [200 mg PO q8h]
- Alt: 450 mg PO q12h; Info: rarely indicated, consult cardiologist
neuropathic pain, diabetic (off-label)
- [10 mg/kg/dose PO qd]
- Start: 150 mg PO qd x3 days then 300 mg PO qd x3 days then 10 mg/kg/dose PO qd; Info: not 1st-line tx
renal dosing
- [no adjustment]
- renal impairment: no adjustment
- HD: no adjustment, on dialysis days administer after dialysis; consider supplement if next maintenance dose not due right after dialysis; PD: no adjustment; no supplement
hepatic dosing
- [adjust dose amount]
- hepatic impairment: decr. usual dose, amount not defined
Peds Dosing .
Peds dosing is currently unavailable or not applicable for this drug.
Contraindications / Cautions .
- hypersensitivity to drug or ingredient
- cardiogenic shock
- caution: AV block, 1st degree
- caution: hepatic impairment
- caution: seizure disorder
- caution: smoking habit change
Drug Interactions .
Overview
mexiletine
antiarrhythmic, class Ib
- CYP1A2 substrate
- CYP2D6 substrate
- CYP1A2 inhibitor, moderate
- affected by altered gastrointestinal motility
- binds to polyvalent cations
- lowers seizure threshold
- urine pH sensitive
Contraindicated
Avoid/Use Alternative
Monitor/Modify Tx
Caution Advised
Adverse Reactions .
Serious Reactions
- ventricular arrhythmia
Common Reactions
- dyspepsia
- dizziness
- tremor
- impaired coordination
- insomnia
- diarrhea
- palpitations
- nervousness
- headache
- tinnitus
- depression
- rash
- dyspnea
- xerostomia
- arthralgia
- fever
- anorexia
- angina
- fatigue
Safety/Monitoring .
Therapeutic Drug Levels
0.5-2 mcg/mL; Toxic Levels: >2 mcg/mL; Timing: <2h before next dose; Time to Steady State: 4-5h; Info: consider levels if hepatic impairment
Monitoring Parameters
Cr, electrolytes at baseline; ECG
Pregnancy/Lactation .
Pregnancy
Clinical Summary
weigh risk/benefit during pregnancy; risk of fetal harm not expected based on limited human data; no known risk of teratogenicity, though risk of fetal death based on animal data at 4x MRHD
Lactation
Clinical Summary
weigh risk/benefit while breastfeeding; no known risk of infant harm based on limited human data and drug properties; no human data available to assess effects on milk production
Pharmacology .
Metabolism: for mexiletine: liver; CYP450: 1A2, 2D6 (primary) substrate
Excretion: for mexiletine: urine (10% unchanged); Half-life: 10-12h, 15.7h (CrCl <10), 25h (severe hepatic impairment)
Subclass: Antiarrhythmics, Oral ; Neuropathy/Neuralgia
Mechanism of Action
for mexiletine: stabilizes membranes; depresses action potential phase 0 (class Ib antiarrhythmic)
Formulary .
No Formulary Selected
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