Which medications in the drug class Antiarrhythmics, Class IB are used in the treatment of Ventricular Tachycardia?

Updated: Dec 05, 2017
  • Author: Steven J Compton, MD, FACC, FACP, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
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Answer

Antiarrhythmics, Class IB

Class IB antiarrhythmics suppress automaticity of conduction tissue by increasing the electrical stimulation threshold of the ventricle and His-Purkinje system and inhibiting spontaneous depolarization of the ventricles during diastole through a direct action on the tissues. These antiarrhythmics block both initiation and conduction of nerve impulses by decreasing the neuronal membrane’s permeability to sodium ions, thereby inhibiting depolarization, with resultant blockade of conduction.

Lidocaine (Xylocaine, Nervocaine, LidoPen, Duo-Trach)

Lidocaine is an IV class IB antiarrhythmic that increases the electrical stimulation threshold of the ventricle, suppressing the automaticity of conduction through the tissue. Although lidocaine may terminate VT successfully, it may increase the overall mortality in peri-infarction VT. It can only be given IV. Its use for VT has declined as a consequence of trials showing IV amiodarone to be superior.

Mexiletine (Mexitil)

Mexiletine is a class IB antiarrhythmic that is indicated for ventricular arrhythmias such as sustained VT. It is a sodium-channel blocker and the closest oral analogue to lidocaine. Mexiletine is generally well tolerated and is occasionally used in patients with VT who respond to IV lidocaine. Class IB sodium channel–blocking drugs are generally felt to be safer than IC drugs, but no large comparative trials exist. This drug is still occasionally used for outpatient VT suppression.


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