mex-IL-e-teen

Therapeutic Classification: antiarrhythmics (class IB)

• Prophylaxis/treatment of serious ventricular arrhythmias, including ventricular tachycardia.

Unlabeled Uses:

• Management of chronic neuropathic pain.

• Decreases the duration of the action potential and effective refractory period in cardiac conduction tissue by altering transport of sodium across myocardial cell membranes.
• Has little or no effect on heart rate.

• Control of ventricular arrhythmias.

Absorption: Well absorbed from the GI tract.

Distribution: Enters breast milk in concentrations similar to plasma.

Metabolism/Excretion: Mostly metabolized by the liver; 10% excreted unchanged by the kidneys.

Half-life: 10–12 hr.

(antiarrhythmic effects†)

†Provided a loading dose has been given.

Contraindicated in:

• Hypersensitivity
• Cardiogenic shock
• 2nd- or 3rd-degree heart block (if a pacemaker has not been inserted)
• Lactation: Lactation.

Use Cautiously in:

• Sinus node or intraventricular conduction abnormalities
• Hypotension
• HF
• Severe hepatic impairment (dosage ↓ suggested)
• OB: Pedi: Safety not established.

CV: palpitations, ARRHYTHMIAS, chest pain, edema.

Derm: rash.

EENT: tinnitus, blurred vision.

GI: nausea, heartburn, vomiting, HEPATIC NECROSIS.

Hemat: blood dyscrasias.

Neuro: dizziness, nervousness, tremor, coordination difficulties , confusion, fatigue, headache, paresthesia, sleep disorder.

Resp: dyspnea.

Drug-Drug:

• Opioid analgesics, atropine, and antacids may slow absorption.
• Metoclopramide may speed absorption.
• Phenytoin, rifampin, cigarette smoking, orphenobarbital may ↑ metabolism and ↓ effectiveness.
• Cimetidine may ↑ levels.
• May ↑ levels and risk of toxicity from theophylline.
• Additive cardiac effects may occur with other antiarrhythmics.
• Drugs that drastically alter urine pH may alter blood levels (alkalinization ↑ reabsorption and blood levels; acidification ↑ excretion and ↓ levels).

Drug-Food:

• Foods that drastically alter urine pH may alter blood levels. Alkalinization ↑ reabsorption and ↑ levels. Acidification ↑ excretion and may ↓ effectiveness (see Appendix M).

• PO (Adults): 400-mg loading dose initially, then 200 mg 8 hr later, then 200–400 mg q 8 hr; dosage alterations of 50–100 mg may be made q 2–3 days. If controlled on 300 mg q 8 hr, can give same daily dose at 12-hr intervals (not to exceed 1200 mg/day). Some patients may require q 6 hr dosing.

(Generic available)

• Capsules: 100 mg; 150 mg; 200 mg; 250 mg;

• Monitor pulse, BP, and ECG periodically throughout therapy. Continuous Holter monitoring and chest x-ray examinations may be necessary to determine efficacy and aid in dose adjustment.
• Pain: Assess type, location, and severity of pain prior to and periodically throughout therapy.

• May occasionally cause a positive ANA test result.
  • May cause a transient increase in AST concentrations.
  • May cause thrombocytopenia within a few days after initiation of therapy. Blood counts usually return to normal within 1 mo after discontinuation of therapy.

• Serum mexiletine concentrations may be determined during dose adjustment. Incidence of side effects is greater with concentrations >2 mcg/mL.

• When changing from other antiarrhythmic therapy, give the 1st dose of mexiletine 6–12 hr after the last dose of quinidine, 3–6 hr after last dose of procainamide. When changing from parenteral lidocaine, decrease lidocaine dose or discontinue lidocaine 1–2 hr after administration of mexiletine or administer lower initial doses of mexiletine.
  • Transfer of patients with life-threatening arrhythmias from other antiarrhythmics to mexiletine should be managed in the hospital.
• PO: Administer with food or antacids to minimize GI irritation.

• Advise patient to take medication exactly as directed, at evenly spaced intervals, even if feeling well. Missed doses should be taken within 4 hr or omitted. Do not skip or double up on missed doses.
• Teach patients to monitor pulse. Advise patient to contact health care professional if pulse rate is <50 bpm or becomes irregular.
• May cause dizziness and light-headedness. Caution patient to avoid driving and other activities requiring alertness until response to medication is known.
• Instruct patient to avoid changes in diet that may drastically acidify or alkalinize the urine (see Appendix M for foods included).
• Advise patient to notify health care professional of disease process and medication regimen prior to treatment or surgery.
• Advise patient to notify health care professional if general tiredness, yellowing of the skin or eyes, fever, sore throat, or persistent side effects occur.
• Patient should carry identification describing disease process and medication regimen at all times.

• Decrease in frequency or resolution of serious ventricular arrhythmias.
• Decrease in severity of chronic neurogenic pain.

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