Mexiletine (Mexitil®) is a medication first developed in the 1980s that belongs to a group of drugs called sodium channel blockers. More specifically, this drug is an Ib sodium channel blocker, and its ability to block sodium movement into cells at certain rates makes it effective as an anti-arrhythmia drug. Since mexiletine can create heart rhythm disturbances, it tends to be used only to treat severe heart arrythmias like ventricular tachycardia. Recent investigation of the drug suggests it has uses in pain relief, too, like another Ib drug, lidocaine, but safety of this medication for a patient who doesn’t already have a condition like ventricular tachycardia is not established.
The medication is administered in two ways. It can be infused through an intravenous line or taken in oral pill form. Some doctors recommend that mexiletine first be given in a hospital setting to observe patient response. After a hospitalized induction phase, patients are sent home. Dosage at home varies by patient and might be anything from 50-1000 milligrams in pill form.
Presently, mexiletine is only recommended for those with severe ventricular arrythmias because it can cause conditions like atrioventricular block. It’s also not recommended for use in pregnant or nursing women. Caution is advised if this drug is taken in concert with other conditions like slow heartbeat, presence of a pacemaker, seizure disorders, and liver disease. The medication doesn’t always work well with other drugs. Patients should talk to their doctors about all medicines, herbs, supplements, and over the counter formulas they take.
Many side effects are reported with use of mexiletine. These can be grouped into adverse effects requiring quick medical intervention, and side effects that are expected, but that should be reported to doctors if they become uncomfortable. In the second group, possible adverse effects include nausea and/or vomiting, blurred vision, dizziness, lightheadedness, feeling nervous, poor coordination, constipation, and tremor.
More severe effects include allergy to mexiletine with symptoms of hives, itchiness, swollen tongue, lips, and mouth, difficulty breathing, and asthma. Other symptoms that are of grave concern are changes to heart rhythm where it is too fast or too slow. Pronounced dizziness, flulike symptoms especially with sore throat, fainting, or bad pain in the stomach are of immediate concern and need medical attention right away.
Another area of concern exists with mexiletine. Since patients may have vision problems or dizziness, they may need help and supervision at first. If the medication continues to impair coordination, balance, equilibrium and/or vision, patients should not drive or operate other types of machinery.