Mexiletine

Pharmacological properties

Mexiletine hydrochloride belongs to class I antiarrhythmic drugs. slows down the rapid transmembrane current of sodium ions, has a membrane-stabilizing and local anesthetic effect. the drug reduces the rate of depolarization and automatism of pacemakers, the speed of excitation in the fibers of the His - Purkinje, slightly reduces the effective refractory period and, to a greater extent, the duration of the action potential (PD), increases the ratio of the effective refractory period to the duration of PD. Mexiletine has little effect on hemodynamic parameters.

Mexiletine hydrochloride is rapidly absorbed in the digestive canal. It binds to plasma proteins by 50-60%. 85% of the administered mexiletine hydrochloride is metabolized in the liver to form inactive metabolites. It is excreted mainly with bile and only 10-15% is excreted in the urine unchanged. The half-life is an average of 11 hours (8-14 hours), with heart failure or with impaired liver function, it can be extended up to 25 hours, with acute myocardial infarction - up to 15-17 hours, and with severe renal failure increases by 30-35 % The drug crosses the placenta, passes into breast milk.

Indications

Prevention and treatment of ventricular extrasystoles, ventricular tachyarrhythmias.

Application

Inside, first 400 mg, then 200 mg every 6–8 hours. It is possible to prescribe a drug of 200–300 mg 3 times a day, if necessary, increase the dose by 50–150 mg every 3 days. the maximum daily dose is 800 mg, with renal failure - not more than 600 mg. in some cases, a single dose has to be increased to 600 mg. in the future, depending on the therapeutic effect, the dose can be gradually reduced. the duration of treatment depends on the severity and course of the disease. the capsule is swallowed whole without chewing, washed down with water.

Contraindications

Hypersensitivity to the drug, sinus node weakness, bradycardia, hypotension, cardiogenic shock, acute renal or hepatic failure, pregnancy, childhood. when prescribing the drug during lactation, it is necessary to decide on the termination of breastfeeding.

Side effects

Possible changes in taste, nausea, vomiting, diarrhea, constipation, nystagmus, disturbance of accommodation, ataxia, dysarthria, tremor, paresthesia, drowsiness, confusion, dizziness. in some cases, the drug can cause bradycardia, hypotension, dermatitis, impaired urination, psychosis, convulsions. arrhythmogenic effect is not excluded (development of ventricular extrasystoles, atrial fibrillation).

special instructions

Due to the possibility of developing life-threatening arrhythmias, drug discontinuation is carried out in a hospital setting. sudden cancellation of mexarhythm is life-threatening, therefore, the dose of the latter must be reduced gradually. when switching from treatment with lidocaine to treatment with mexarhythm, it is necessary to stop the lidocaine infusion immediately after taking the first dose of mexarhythm, while the system for iv administration of lidocaine is disconnected from the patient only after achieving a satisfactory antiarrhythmic effect using mexarhythm.

With caution, the drug is prescribed for patients with myasthenia, epilepsy, mental illness; with bradycardia, arterial hypotension, heart failure; diseases of the liver or kidneys. Meksaritm enhances the symptoms and severity of Parkinsons disease. During treatment with Mexarhythm, you should refuse to drive vehicles and work with potentially dangerous mechanisms. There is no experience with the use of the drug in children.

Interactions

Narcotic, sedative and ganglioblocking agents, antacids, metoclopramide, anticholinergics, n2-histaminoblockers slow down the absorption of mexarhythm; β-adrenoreceptor blockers, calcium antagonists - binding to plasma proteins. rifampicin, phenytoin and barbiturates accelerate the metabolism of the drug, reduce its concentration in the blood. sodium bicarbonate and diuretics slow the excretion of mexarhythm by the kidneys, increasing its concentration in blood plasma.with combined use of the drug with β-adrenoreceptor blockers or membrane stabilizing agents, an increase in the antiarrhythmogenic effect is observed, with lidocaine or other local anesthetics, the risk of cumulation of mexarhythm increases.

Overdose

Manifested by nausea, vomiting. possible diarrhea, constipation, drowsiness, hypotension, proarrhythmogenic effect. it is necessary to rinse the stomach, prescribe activated charcoal. symptomatic treatment.

Storage conditions

In a dry, dark place at a temperature of 15-25 ° C. Shelf life is 2 years.