Adult:
As hydrochloride: 400 mg as loading dose followed after 2 hr by 200-250 mg 3-4 times daily. Maintenance: 600-900 mg daily in divided doses. Max dose: 1200 mg daily. Patient with MI: Higher loading dose e.g. 600 mg may be needed, especially if opioid analgesics were also given.
Intravenous
TREATMENT OF VENTRICULAR ARRHYTHMIAS
Adult:
As hydrochloride: 100-250 mg slow inj at 25 mg/min followed by 250 mg infusion over 1 hr, 250 mg for the next 2 hr and then 0.5 mg/min for maintenance, according to response. Transfer to oral dose of 200-250 mg 3-4 times daily when possible. Alternatively, 200 mg at 25 mg/min followed by 400 mg orally upon completion of inj, with subsequent oral dose of 200-250 mg 3-4 times daily.
Administration
Should be taken with food.
Precautions
Acute MI, sinus node dysfunction, conduction defects, bradycardia, hypotension, heart failure, hepatic impairment. Monitor ECG and BP. Correct electrolyte imbalance prior to and during therapy. Pregnancy.
Potentially Life-threatening
Adverse Drug Reactions
Increased risk of arrhythmias with other antiarrhythmics or arrhythmogenic drugs. May precipitate lidocaine toxicity.
Levels/effects may be reduced with CYP1A2 inducers (e.g. aminoglutethimide, carbamazepine, phenobarbital, rifampicin). Levels/effects may be increased with CYP1A2 inhibitors (e.g. ciprofloxacin, ketoconazole, norfloxacin, ofloxacin, rofecoxib), CYP2D6 inhibitors (e.g. chlorpromazine, delavirdine, fluoxetine, miconazole, paroxetine, pergolide, quinidine, quinine, ritonavir, ropinirole) and urinary alkalinisers (e.g. antacids, sodium bicarbonate, acetazolamide). May increase the levels/effects of CYP1A2 substrates e.g. aminophylline, fluvoxamine, mirtazapine, ropinirole, theophylline, trifluoperazine. Clearance reduced with fluvoxamine. Delayed absorption with opioid analgesics.
Food may reduce rate but not the extent of oral absorption. Avoid dietary changes that alter urine pH since these may increase or decrease excretion of mexiletine.
