WARNINGS
Mortality: In the National Heart, Lung and Blood Institute's Cardiac Arrhythmia Suppression Trial (CAST), a long-term, multicentered, randomized, double-blind study in patients with asymptomatic non-life-threatening ventricular arrhythmias who had a myocardial infarction more than six days but less than two years previously, an excessive mortality or non-fatal cardiac arrest rate (7.7%) was seen in patients treated with encainide or flecainide compared with that seen in patients assigned to carefully matched placebo-treated groups (3.0%). The average duration of treatment with encainide or flecainide in this study was ten months.
The applicability of the CAST results to other populations (e.g., those without recent myocardial infarction) is uncertain. Considering the known proarrhythmic properties of MEXITIL and the lack of evidence of improved survival for any antiarrhythmic drug in patients without life-threatening arrhythmias, the use of MEXITIL as well as other antiarrhythmic agents should be reserved for patients with life-threatening ventricular arrhythmia.
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MEXITIL SUMMARY
Mexitil®
(mexiletine hydrochloride, USP)
MEXITIL® (mexiletine hydrochloride, USP) is an orally active antiarrhythmic agent available as 150 mg, 200 mg and 250 mg capsules. 100 mg of mexiletine hydrochloride is equivalent to 83.31 mg of mexiletine base. It is a white to off-white crystalline powder with slightly bitter taste, freely soluble in water and in alcohol. MEXITIL has a pKa of 9.2.
MEXITIL (mexiletine hydrochloride, USP)is indicated for the treatment of documented ventricular arrhythmias, such as sustained ventricular tachycardia, that, in the judgement of the physician, are life-threatening. Because of the proarrhythmic effects of MEXITIL, its use with lesser arrhythmias is generally not recommended. Treatment of patients with asymptomatic ventricular premature contractions should be avoided.
Initiation of MEXITIL treatment, as with other antiarrhythmic agents used to treat life-threatening arrhythmias, should be carried out in the hospital.
Antiarrhythmic drugs have not been shown to enhance survival in patients with ventricular arrhythmias.
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NEWS HIGHLIGHTS
Published Studies Related to Mexitil (Mexiletine)
Morphine versus mexiletine for treatment of postamputation pain: a randomized, placebo-controlled, crossover trial. [2008.08]
BACKGROUND: Stump and phantom pains are debilitating sequelae of amputations that are often resistant to treatment. The efficacy of pharmacologic therapies, including opioids and sodium channel blockers, for postamputation pain is uncertain... CONCLUSIONS: Therapy with morphine, but not mexiletine, resulted in a decrease in intensity of postamputation pain but was associated with a higher rate of side effects and no improvement in self-reported levels of overall functional activity and pain-related interference in daily activities.
Effect of mexiletine on dynamic allodynia induced by chronic constriction injury of the sciatic nerve in rats. [2009.07]
Static and dynamic allodynia occurred in a rat model of neuropathic pain induced by chronic constriction injury (CCI) of the sciatic nerve. Static allodynia was detected within 1 day after the CCI surgery, and persisted for 28 days.
Experience with oral mexiletine in primary erythromelalgia in children. [2009.07]
Primary erythromelalgia is characterized by burning pain, redness, and warmth in the extremities. We present two cases of primary erythromelalgia both of whom presented with a history of several months of severe burning pain in both hands and feet... We observed no adverse effects with mexilitine therapy.
Mexiletine-responsive erythromelalgia due to a new Na(v)1.7 mutation showing use-dependent current fall-off. [2009.04]
Inherited erythromelalgia (IEM), characterized by episodic burning pain and erythema of the extremities, is produced by gain-of-function mutations in sodium channel Na(v)1.7, which is preferentially expressed in nociceptive and sympathetic neurons. Most patients do not respond to pharmacotherapy, although occasional reports document patients as showing partial relief with lidocaine or mexiletine...
Mexiletine for refractory chronic daily headache: a report of nine cases. [2008.11]
OBJECTIVE: To describe the use of mexiletine in the treatment of chronic daily headache in a refractory headache population. BACKGROUND: Intravenous lidocaine is a novel treatment for chronic daily headache with medication overuse and SUNCT syndrome.DISCUSSION: The preliminary study suggests mexiletine is a useful preventative treatment for some patients with chronic daily headache, including refractory patients with medication overuse or those who have failed multiple preventatives in the past.
Clinical Trials Related to Mexitil (Mexiletine)
Mexiletine in Non-Dystrophic Myotonia [Not yet recruiting]
Non-dystrophic myotonias are a group of rare muscle disorders caused by abnormalities in
different muscle cell membrane proteins. Patients experience delayed muscle relaxation that
causes impaired physical activity, stiffness, and pain. Mexiletine has been shown to be
beneficial for symptoms of myotonia in case reports of patients with non-dystrophic myotonia,
however, current management of these patients primarily depends on individual practitioners'
preference. The results, if positive, will permit the identification of mexiletine as an
effective therapy for myotonia, making it a first-line therapy for patients with
non-dystrophic myotonia.
A Phase II/III Double-Blind Study of Amitriptyline and Mexiletine for Painful Neuropathy in HIV Infection [Completed]
To assess the efficacy, safety, and tolerability of amitriptyline hydrochloride versus
mexiletine hydrochloride in reducing pain intensity in patients with HIV-related painful
peripheral neuropathy.
No large-scale controlled clinical trials of symptomatic therapy for painful HIV-related
neuropathy have been attempted. Both amitriptyline and mexiletine have been useful in the
management of painful neuropathies; however, both are associated with certain toxicities. In
this comparative study of amitriptyline and mexiletine, benztropine mesylate also will be
included as an active placebo to mimic the side effects of the study drugs.
Efficacy of Opioids and Mexiletine for the Treatment of Postamputation Pain [Completed]
Persistent pain occurs in 50-85 percent of patients who experience the amputation of an
extremity. This study will compare the effectiveness of morphine and mexiletine to placebo
in the treatment of postamputation pain.
It is hypothesized that the effects of opioids and mexiletine on behavior and mental
functioning in patients with postamputation pain are unlikely to be significant barriers to
the clinical use of the drugs.
Mexiletine for the Treatment of Focal Dystonia [Completed]
Dystonia refers to a condition characterized by involuntary muscle contractions that may
cause pain, abnormal posture, or abnormal movements. The cause of dystonia is unknown, but
some researchers believe it is a result of overactivity in the areas of the brain responsible
for movement (basal ganglia).
Lidocaine is a drug used for the treatment of irregular heartbeats. It is given by
injection. Recent studies have shown that lidocaine is also effective for the treatment
dystonia. Mexiletine is a drug similar to lidocaine used for irregular heartbeats that can
be taken by mouth.
Researchers would like to test the effectiveness of Mexiletine for the treatment of dystonia.
Patients participating in the study will be divided into two groups;
Group 1 will take Mexiletine for six weeks then stop. They will remain drug free for one
week then begin taking a placebo "inactive sugar pill" for an additional six weeks.
Group 2 will take a placebo "inactive sugar pill" for six weeks then stop. They will remain
drug free for one week then begin taking a Mexiletine for an additional six weeks.
Throughout the study researchers will test the effectiveness of the treatment by evaluating
patients using clinical rating scales and neurophysiological studies. In addition,
researchers will test patient's reflexes in an attempt to find out where mexiletine works in
the nervous system.
Effectiveness of Mexiletine for Treating People With Non-Dystrophic Myotonia [Recruiting]
Nondystrophic myotonias (NDM) are neuromuscular disorders caused by genetic abnormalities in
certain muscle cell membrane proteins. The proteins affect muscle contraction. Individuals
with NDM experience limited muscle relaxation, which then can cause pain, weakness,
incoordination, and impaired physical activity and function. Because NDM is very rare,
information on the best way to treat people with the disorders is lacking, and there are no
FDA-approved therapies. The purpose of this study is to determine the effectiveness of the
medication mexiletine in treating people with NDM.
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