Stahl's Essential Psychopharmacology Online
In Collaboration With
Mexiletine
Therapeutics
Brands
• Mexitil
Generic?
Yes
Class
• Antiarrhythmic
Commonly Prescribed for
(FDA approved in bold)
• Cardiac arrhythmias
• Symptomatic myotonia (myotonia congenita, myotonic dystrophy)
• Pain in peripheral neuropathy
• Intractable headache
How the Drug Works
• Class
1B antiarrhythmic agent that depresses phase 0 (reduces the rate of
rise of the action potential). An oral analogue
of lidocaine. It has actions on
surfaces and membranes of skeletal muscle and neuronal sodium-channel
blocking properties.
It also reduces the effective
refractory period in Purkinje fibers
How Long Until It Works
• Antiarrhythmic effect will occur within hours, although it may take time to find optimal dose. May take more time (days or
weeks) to see relief and determine most effective dose in myotonia or pain disorders
If It Works
• Continue to use with appropriate monitoring
If It Doesn't Work
• Check serum levels and if not effective change to an alternative agent
Best Augmenting Combos for Partial Response or Treatment-Resistance
• Myotonia: Quinine and other anticonvulsants are occasionally used. Phenytoin is also effective but has similar antiarrhythmic
properties and may interact with mexiletine
• Neuropathic pain: other anticonvulsants and antidepressants can be used
Tests
• Monitor hepatic enzymes and CBC during therapy. Obtain ECG at baseline and for any new symptoms. Check a serum mexiletine
level to guide therapy and for any AEs