Mexiletine Side Effects

Brand Names: Mexitil

Please note - some side effects for Mexiletine may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).

Side Effects of Mexiletine - for the Consumer

Mexiletine

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Mexiletine:

Blurred vision; clumsiness; constipation; diarrhea; dizziness or lightheadedness; headache; heartburn; incoordination; nausea; nervousness; stomach discomfort; tremor; vomiting.

Severe allergic reactions (rash; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision or other vision problems; chest pain; fainting; fever; irregular, fast, or slow heartbeat; severe dizziness or lightheadedness; severe stomach pain; sore throat; yellowing of the skin or eyes.

Mexiletine Side Effects - for the Professional

Mexiletine

Mexiletine hydrochloride commonly produces reversible gastrointestinal and nervous system adverse reactions but is otherwise well tolerated. Mexiletine has been evaluated in 483 patients in one month and three month controlled studies and in over 10,000 patients in a large compassionate use program. Dosages in the controlled studies ranged from 600 to 1200 mg/day; some patients (8%) in the compassionate use program were treated with higher daily doses (1600 to 3200 mg/day). In the three month controlled trials comparing Mexiletine to quinidine, procainamide and disopyramide, the most frequent adverse reactions were upper gastrointestinal distress (41%), lightheadedness (10.5%), tremor (12.6%) and coordination difficulties (10.2%). Similar frequency and incidence were observed in the one month placebo-controlled trial. Although these reactions were generally not serious, and were dose-related and reversible with a reduction in dosage, by taking the drug with food or antacid or by therapy discontinuation, they led to therapy discontinuation in 40% of patients in the controlled trials. Table 1 presents the adverse events reported in the one-month placebo-controlled trial.

Table 1: Comparative Incidence (%) of Adverse Events Among Patients Treated with Mexiletine and Placebo in the 4 Week, Double-blind Crossover Trial

Table 2 presents the adverse reactions occurring in one percent or more of patients in the three month controlled studies.

Table 2: Comparative Incidence (%) of Adverse Events Among Patients Treated with Mexiletine or Control Drugs in the 12 Week Double-blind Trials

Less than 1%: Syncope, edema, hot flashes, hypertension, short-term memory loss, loss of consciousness, other psychological changes, diaphoresis, urinary hesitancy/retention, malaise, impotence/decreased libido, pharyngitis, congestive heart failure.

An additional group of over 10,000 patients has been treated in a program allowing administration of Mexiletine hydrochloride under compassionate use circumstances. These patients were seriously ill with the large majority on multiple drug therapy. Twenty-four percent of the patients continued in the program for one year or longer. Adverse reactions leading to therapy discontinuation occurred in 15 percent of patients (usually upper gastrointestinal system or nervous system effects). In general, the more common adverse reactions were similar to those in the controlled trials. Less common adverse events possibly related to Mexiletine use include:

Cardiovascular System

Syncope and hypotension, each about 6 in 1000; bradycardia, about 4 in 1000; angina/angina-like pain, about 3 in 1000; edema, atrioventricular block/conduction disturbances and hot flashes, each about 2 in 1000; atrial arrhythmias, hypertension and cardiogenic shock, each about 1 in 1000.

Central Nervous System

Short-term memory loss, about 9 in 1000 patients; hallucinations and other psychological changes, each about 3 in 1000; psychosis and convulsions/seizures, each about 2 in 1000; loss of consciousness, about 6 in 10,000.

Digestive

Dysphagia, about 2 in 1000; peptic ulcer, about 8 in 10,000; upper gastrointestinal bleeding, about 7 in 10,000; esophageal ulceration, about 1 in 10,000. Rare cases of severe hepatitis/acute hepatic necrosis.

Skin

Rare cases of exfoliative dermatitis and Stevens-Johnson syndrome with Mexiletine treatment have been reported.

Laboratory

Abnormal liver function tests, about 5 in 1000; positive ANA and thrombocytopenia, each about 2 in 1000; leukopenia (including neutropenia and agranulocytosis), about 1 in 1000; myelofibrosis, about 2 in 10,000 patients.

Other

Diaphoresis, about 6 in 1000; altered taste, about 5 in 1000; salivary changes, hair loss and impotence/decreased libido, each about 4 in 1000; malaise, about 3 in 1000; urinary hesitancy/retention, each about 2 in 1000; hiccups, dry skin, laryngeal and pharyngeal changes and changes in oral mucous membranes, each about 1 in 1000; SLE syndrome, about 4 in 10,000.

Hematology

Blood dyscrasias were not seen in the controlled trials but did occur among 10,867 patients treated with Mexiletine in the compassionate use program.

Myelofibrosis was reported in two patients in the compassionate use program; one was receiving long-term thiotepa therapy and the other had pretreatment myeloid abnormalities.

In postmarketing experience, there have been isolated, spontaneous reports of pulmonary changes including pulmonary infiltration and pulmonary fibrosis during Mexiletine therapy with or without other drugs or diseases that are known to produce pulmonary toxicity. A causal relationship to Mexiletine therapy has not been established. In addition, there have been isolated reports of drowsiness, nystagmus, ataxia, dyspepsia, hypersensitivity reaction, and exacerbation of congestive heart failure in patients with pre-existing compromised ventricular function. There have been rare reports of pancreatitis associated with Mexiletine treatment.

Side Effects by Body System

General

Generally, mexiletine has been well tolerated. Side effects usually have been reversible and dose-related. The most common side effects associated with mexiletine therapy have been gastrointestinal and nervous system effects. The incidence of side effects increases at serum levels greater than 2.0 mcg/mL.

Gastrointestinal

A case of mexiletine esophageal ulceration has been reported. Mexiletine was continued following a dosage reduction and an increase in the dosing interval.

Gastrointestinal side effects have occurred most frequently. Nausea, anorexia, constipation and dyspepsia have been reported in 10% to 40% of patients, primarily during the first 3 to 4 weeks of therapy. Administration with food usually reduced gastrointestinal side effects. Diarrhea was reported in 7% of patients. Dysphagia, salivary changes, altered taste, changes in oral mucosa, hiccups, peptic ulcer disease, upper GI bleeding, and esophageal ulceration have been reported rarely.

Nervous system

Nervous system side effects have included fine hand tremor (10%), dizziness (up to 25%), and difficulties with coordination (10.2%). These symptoms may be the first signs of toxicity. Ataxia, dysarthria, drowsiness, paresthesias, nervousness, speech difficulties, depression, and confusion have been reported less frequently. Short-term memory loss, malaise, seizures, and loss of consciousness have occurred.

Cardiovascular

Rare cases of torsades de pointes have been associated with mexiletine. New or worsened congestive heart failure has been reported in 1% to 3% of patients.

A case of new first-degree AV heart block and left bundle branch block associated with elevated mexiletine serum levels (34 mcg/mL) was reported.

Cardiovascular symptoms of palpitation and chest pain have occurred in up to 7.5% of patients. A proarrhythmic effect has been reported in approximately 10% of patients and angina 1.7%. Mexiletine has little effect on cardiac contractility. Syncope, hypotension, hypertension, bradycardia, conduction disturbances, atrial arrhythmias, edema, and congestive heart failure have occurred.

Hematologic

Hematologic side effects are rare and have included reports of thrombocytopenia, which is thought to be due to an IgM cold agglutinin.

Hypersensitivity

A generalized pruritic, erythematous, papular rash has been reported in a 77-year-old man.

Hypersensitivity rashes have been reported rarely.

Hepatic

Hepatic side effects have been rare. Isolated cases of mild reversible elevations in liver function tests which resolved after two to three weeks after stopping mexiletine have occurred. Rare cases of severe hepatitis or acute hepatic necrosis have been reported.

Respiratory

Respiratory abnormalities including dyspnea have occurred in 3.7% to 5.7% of patients.

A case of fatal diffuse interstitial pulmonary fibrosis has been associated with mexiletine in a 75-year-old man who had previously taken procainamide and disopyramide. Symptoms of dyspnea preceded chest X-ray abnormalities by months. The diagnosis was made following pulmonary function tests, chest CT scan, and an open lung biopsy.

Ocular

Ocular side effects including diplopia, nystagmus, and blurred vision have been reported in up to 7.5% of patients.

Dermatologic

Dermatologic side effects have been uncommon, however, rash has been reported in up to 4.2% of patients. Rare cases of exfoliative dermatitis and Stevens-Johnson Syndrome have occurred. Diaphoresis, hot flashes, and dry skin have been reported.

Genitourinary

Genitourinary side effects including urinary hesitancy and retention have occurred rarely. Impotence and decreased libido have been reported.

Psychiatric

Psychiatric side effects including psychosis and hallucinations have been reported.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date, and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This information does not endorse drugs, diagnose patients, or recommend therapy. This drug information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug of drug combination is safe, effective, or appropriate for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of information provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse, or pharmacist.