Mexiletine Hydrochloride Tablets

It is a class Ib antiarrhythmic drug that can inhibit sodium influx in myocardial cells, reduce the speed of phase 0 depolarization of action potential, and shorten the effective refractory period of Purkinje fibers. In patients with normal cardiac conduction system, mexiletine has little effect on the generation and conduction of cardiac impulses. Clinical trials have not found that mexiletine causes II or III degree atrioventricular block. Mexiletine does not prolong the duration of ventricular depolarization and repolarization, so it can be used for ventricular arrhythmias with prolonged QT interval. The drug has antiarrhythmic, anticonvulsant and local anesthetic effects. It has a small inhibitory effect on the myocardium. The effective blood concentration of mexiletine is 0.5-2ug/ml, and the toxic blood concentration is close to the effective blood concentration, which is above 2ug/ml. A small number of patients can experience serious adverse reactions at the effective blood concentration.

The chemical name of this product is: 1-(2,6-dimethylphenoxy)-2-propylamine hydrochloride. Molecular formula: C11H17NOHCl Molecular weight: 215.72.

This product is white tablets.

This product is suitable for chronic ventricular arrhythmias, including ventricular premature beats and ventricular tachycardia.

Oral: 200-300 mg for the first dose, and 100-200 mg after 2 hours if necessary. The general maintenance dose is about 400-800 mg per day, divided into 2-3 doses. The maximum dose for adults is 1200 mg per day, divided into 2 doses.

About 20%-30% of patients experience adverse reactions after oral administration. 1 Gastrointestinal reactions: the most common. Including nausea, vomiting, etc. There are reports of abnormal liver function, including increased GOT. 2 Neurological: the second most common adverse reaction. Including dizziness, tremor (first appearing hand tremor), ataxia, nystagmus, drowsiness, coma and convulsions, diplopia, blurred vision, mental disorder, insomnia. 3 Cardiovascular: Sinus bradycardia and sinus arrest generally occur less frequently. Occasionally, chest pain, arrhythmogenic effects such as ventricular tachycardia, hypotension and heart failure are exacerbated. Treatment includes discontinuation of medication, use of atropine, pressor drugs, pacemakers, etc. 4 Allergic reactions: rash. 5 Very few cases have leukopenia and thrombocytopenia.

It is contraindicated in patients with cardiogenic shock, II or III degree atrioventricular block, and sick sinus syndrome.

Precautions for children: The safety and effectiveness of mexiletine hydrochloride in children are not yet clear. Precautions for pregnancy and lactation: 1. No teratogenic or reproductive effects were found in pregnant rats, mice, and rabbits at a dose of 4 times the maximum human oral dose, but there are no related reports in humans, so it is only used for treatment that is beneficial to the fetus. 2. The concentration of mexiletine hydrochloride in breast milk is the same as that in maternal blood, so it is recommended that lactating women not use this drug. Precautions for the elderly: Liver function needs to be monitored when taking the drug in the elderly.

1 Clinical trials have reported that there is no mutual effect between mexiletine and commonly used anti-anginal, antihypertensive and antifibrinolytic drugs. 2 The therapeutic effect of mexiletine combined with quinidine, propranolol or amiodarone is better. It can be used for refractory ventricular arrhythmias that are ineffective with a single drug. However, it should not be used in combination with Class Ib drugs. 3 If phenytoin sodium or other liver enzyme inducers such as rifampicin and phenobarbital are used in combination with mexiletine, the blood concentration of mexiletine can be reduced. 4 It has been reported that benzodiazepines do not affect the blood concentration of mexiletine. 5 The combination of mexiletine and digoxin, diuretics and propranolol does not affect the PR, QRS and QT intervals of the electrocardiogram. 6 In the early stage of acute myocardial infarction, morphine delays and reduces the absorption of this product, which may be related to delayed gastric emptying. 7 Antacids can reduce the blood concentration of this product when taken orally, but the blood concentration may also increase due to increased urine pH.

Keep away from light, tightly closed and in a cool place.

0.1g

24 months