Mexiletene

Mechanism :

It is a class 1B antiarrhythmic used in the treatment of ventricular arrhythmias.

Indication :

Ventricular tachycardia Premature ventricular beats Prevention of ventricular fibrillation.

Contraindications :

Hypersensitivity cardiogenic shock caution if 1st degree AV block, seizure disorder, smoking habit changes.

Dosing :

1.4-5 mg/kg/dose PO every 8 hourly. Begin with lower dose and titrate upwards.

Adverse Effect :

Nausea, vomiting, heartburn, light-headedness, arrhythmias, bradycardia, hypotension, dizziness, tremor, ataxia, weakness, GI discomfort.

Interaction :

Aminophylline Mexiletine increases the effect and toxicity of theophylline Bendamustine Affects hepatic CYP1A2 metabolism, thus increasing bendamustine levels. Concentration of active metabolites may be decreased due to decreased conversion. Dyphylline Mexiletine increases the effect and toxicity of theophylline Eltrombopag Affects hepatic CYP1A2 metabolism, increases Eltrombopag level or affect. Ethotoin The hydantoin decreases the effect of mexiletine Etravirine Mexiletine, when used concomitantly with etravirine (a strong CYP3A4 inducer), may experience a decrease in serum concentration. It is recommended to monitor mexiletine therapy for reduced effectiveness. Fluvoxamine Fluvoxamine may increase the therapeutic and adverse effects of mexiletine. Fosphenytoin The hydantoin decreases the effect of mexiletine Mephenytoin The hydantoin decreases the effect of mexiletine Oxtriphylline Mexiletine increases the effect and toxicity of theophylline Phenytoin The hydantoin decreases the effect of mexiletine Propafenone Propafenone may increase the effect and toxicity of mexilitine. Ramelteon Mexiletine increases levels/toxicity of ramelteon Rifampicin Rifampin decreases the effect of mexiletine Tacrine The metabolism of Tacrine, a CYP1A2 substrate, may be reduced by strong CYP1A2 inhibitors such as Mexiletine. Consider modifying therapy to avoid Tacrine toxicity. Monitor the efficacy and toxicity of Tacrine if Mexiletine is initiated, discontinued or if the dose is changed. Terbinafine Terbinafine may reduce the metabolism and clearance of Mexiletine. Consider alternate therapy or monitor for therapeutic/adverse effects of Mexiletine if Terbinafine is initiated, discontinued or dose changed. Terfenadine Increased risk of cardiotoxicity and arrhythmias Theophylline Mexiletine increases the effect and toxicity of theophylline Thiothixene The strong CYP1A2 inhibitor, Mexiletine, may decrease the metabolism and clearance of Thiothixene, a CYP1A2 substrate. Consider alternate therapy or monitor for changes in Thiothixene therapeutic and adverse effects if Mexiletine is initiated, discontinued or dose changed. Tizanidine Mexilitene may decrease the metabolism and clearance of Tizanidine. Consider alternate therapy or use caution during co-administration. Vilazodone Monitor for increased serum concentrations/toxic effects of mexiletine if a selective serotonin reuptake inhibitor (SSRI) is initiated/dose increased, or decreased concentrations/effects if an SSRI is discontinued/dose decreased.

Renal Dose :

Dose in Renal Impairment GFR (mL/min)

20-50	Dose as in normal renal function
10-20	Dose as in normal renal function
<10	50–75% of normal dose and titrate according to response

Dose in Patients undergoing Renal Replacement Therapies

CAPD	Not dialysed. Dose as in GFR<10 mL/min
HD	Not dialysed. Dose as in GFR<10 mL/min
HDF/High flux	Dialysed. Dose as in GFR<10 mL/ min
CAV/VVHD	Not dialysed. Dose as in normal renal function

Hepatic Dose :

Based on experience in adult patients with hepatic impairment or hepatic congestion secondary to heart failure, dosing adjustment suggested; half-life is approximately doubled in adult patients with hepatic impairment.