Mexiletine dosage must be individualized on the basis of response and tolerance. Administration with food is recommended. Initiate Mexiletine hydrochloride therapy with 200 mg every 8 hours when rapid control of arrhythmia is not essential. A minimum of two to three days between dose adjustments is recommended. The dose may be adjusted up or down in 50 or 100 mg increments. Most patients achieve satisfactory control with between 200 - 300 mg every 8 hours.The total daily dose should not exceed 400 mg.

HEK293 cells stably expressing human homolog of human Nav1.5 and human Nav1.7 channels were maintained under standard tissue culture conditions (5% CO2; 37°C) in Dulbecco’s modified Eagle’s medium and F-12 medium mixture at 1:1 supplemented with 10% fetal bovine serum under selection of antibiotic G418 with a concentration of 500 μg/mL. Cells were passaged every three days with 0.25% Trypsin-EDTA. Whole-cell recordings were performed 18–24 h after plating at room temperature. Whole-cell patch-clamp recordings were conducted at room temperature (22–25°C) using an EPC-10 USB amplifier. The pipette solution contained (in mM): 140 CsF, 10 NaCl, 1 EGTA, and 10 HEPES; pH 7.3 with CsOH. The bath solution for recording contained (in mM): 140 NaCl, 3 KCl, 10 HEPES, 1 MgCl2, 1 CaCl2; pH 7.3 with NaOH. Mexiletine was diluted in bath solution to the desired concentration. Bath application of 0.3 mM mexiletine resulted in a reduction of Nav1.5 or Nav1.7 currents, while V1/2 values were not significantly shifted for even up to 1.0 mM.