mexiletine (Rx)

Brand and Other Names:
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

capsule

  • 150mg
  • 200mg
  • 250mg

Ventricular Arrhythmias (Life-Threatening)

Initial: 200 mg PO q8hr; may load with 400 mg followed by 200 mg PO q8hr if necessary for rapid control of ventricular arrhythmia

Dose range: 200-300 mg PO q8hr

May increase to 400 mg q8hr; not to exceed 1200 mg/day

Take with food or antacid

Therapeutic range: 0.5-2 mg/L

Organ Transplant Rejection (Orphan)

Prevention of acute and chronic rejection in patients who have received solid organ transplants

Orphan indication sponsor

  • James W Williams, MD; Rush-Presbyterian-St. Luke's Medical Ctr, Dept o, 1653 West Congress Parkway; Chicago, IL 60612-3833

Myotonia (Orphan)

Treatment of nondystrophic myotonia

Orphan indication sponsor

  • University of Rochester Medical Center; 1351 Mt. Hope Ave, Suite 203; Rochester, NY 14620

Renal Impairment

CrCl<10 mL/min: 50-75% of normal dose

Hepatic Impairment

Liver impairment or CHF: 25-30% of normal dose

Not FDA approved

Usual dose for arrhythmias: 2.5-5 mg/kg PO q8hr

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Interactions

Interaction Checker

and mexiletine

No Results

     activity indicator 
    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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            Adverse Effects

            >10%

            Nausea (40%)

            Vomiting (40%)

            Heartburn (40%)

            Ataxia (20%)

            Dizziness (20-25%)

            Lightheadedness (11-25%)

            Tremor (13%)

            1-10%

            Coordination difficulties (10%)

            Palpitation (4-7%)

            Hypotension (4-8%)

            Angina (2%)

            Headache (5-7%)

            Depression (2%)

            Xerostomia (3%)

            Proarrhythmia (10-15%)

            Rash (4%)

            Insomnia (5-7%)

            Confusion (5-7%)

            Chest pain (3-8%)

            Abdominal pain (1%)

            Dyspnea (3%)

            Constipation or diarrhea (4-5%)

            Premature ventricular contractions (1-2%)

            Blurred vision (5-7%)

            Nystagmus (6%)

            Frequency Not Defined

            Edema

            Exacerbation of CHF

            Pulmonary fibrosis

            Proarrhythmia

            Convulsions

            Mouth sores

            Tinnitus

            Systemic lupus erythematosus

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            Warnings

            Black Box Warnings

            National Heart, Lung, and Blood Institute's Cardiac Arrhythmia Suppression Trial (CAST): Excessive mortality or nonfatal cardiac arrest (7.7%) shown with encainide or flecainide compared with placebo (3%)

            CAST was a long-term, multicenter, randomized, double-blind study in patients with asymptomatic non-life-threatening ventricular arrhythmias who had a myocardial infarction (MI) >6 days but <2 yr previously

            Average duration of treatment w/ encainide or flecainide in CAST was 10 months

            Applicability of CAST results to other populations (eg, patients without recent MI) is uncertain

            Reserve use of Class IC antiarrhythmics for life-threatening ventricular arrhythmias: Considering the known proarrhythmic properties of mexiletine & lack of evidence of improved survival for any antiarrhythmic drug in patients without life-threatening arrhythmias, mexiletine use, as well as other antiarrhythmic agents, should be reserved for patients with life-threatening ventricular arrhythmias

            Contraindications

            Hypersensitivity to mexiletine

            Cardiogenic shock, 2°/3° AV block without pacemaker

            Cautions

            Use caution in CHF, hypotension, history of seizures

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

            Hepatic toxicity may occur

            Correct electrolyte imbalances

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

            Monitor and adjust dose to prevent QTc prolongation

            Seizure disorders, pregnancy

            Good for automatic and reentrant arrhythmias, not PSVT's

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            Pregnancy & Lactation

            Pregnancy Category: C

            Lactation: enters breast milk at concs comparable to maternal plasma (AAP Committee states compatible w/ nursing)

            Pregnancy Categories

            A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA: Information not available.

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            Pharmacology

            Mechanism of Action

            Class 1B antidysrhythmic; combines with fast Na channels & thereby inhibits recovery after repolarization resulting in decreasing myocardial excitability & conduction velocity

            Pharmacokinetics

            Bioavailability: 80-90%

            Protein Bound: 50-60%

            Half-Life: 10-14 hr (adults)

            Peak Plasma Time: 2-3 hr (PO)

            Therapeutic range: 0.5-2 mcg/mL

            Toxicity range: >2 mcg/mL

            Vd: 5-7 L/kg

            Metabolism: in liver to form parahydroxymexiletine & 2-hydroxymexiletine mainly by hepatic P450 enzyme CYP2D6 & partially by CYP1A2

            Metabolites: parahydroxymexiletine & 2-hydroxymexiletine (inactive)

            Excretion: urine 10-15%

            Dialyzable: HD: No; PD: No

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            Formulary

            FormularyPatient Discounts

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            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
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            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
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            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.