Mexiletine

Use caution in CHF, hypotension, history of seizures

Monitor and adjust dose to prevent QTc prolongation

Patients with second or third-degree heart block may be treated if continuously monitored; use caution when used in such patients or in patients with pre-existing sinus node dysfunction or intraventricular conduction abnormalities

Use in less severe arrhythmias not recommended; avoid in treatment of asymptomatic ventricular premature contractions or conduction disturbances

Some abnormal liver function tests reported in first few weeks of therapy; most have been observed in setting of congestive heart failure or ischemia; patients with liver disease should be followed carefully while receiving therapy; caution should also be observed in patients with hepatic dysfunction secondary to congestive heart failure

Rare instances of severe liver injury, including hepatic necrosis, reported in association with treatment; recommended that patients in whom an abnormal liver test has occurred, or who have signs or symptoms suggesting liver dysfunction, be carefully evaluated; if persistent or worsening elevation of hepatic enzymes is detected, consider discontinuing therapy

Prior to use electrolyte imbalances (especially hypokalemia or hypomagnesemia) must be corrected

Avoid concurrent drug therapy or dietary regimens which may markedly alter urinary pH during therapy; the minor fluctuations in urinary pH associated with normal diet do not affect excretion of drug

Marked leukopenia, agranulocytosis and mild depressions of leukocytes and thrombocytopenia reported (rare); If significant hematologic changes observed, patient should be carefully evaluated, and, if warranted, therapy should be discontinued; blood counts usually return to normal within one month of discontinuation