antiarrhythmic agent, Group IB

^[1]^[2]

Indications

class Ib antiarrhythmic agents shorten both the action potential duration & refractoriness at high concentrations
thus class Ib agents possess local anesthetic & membrane stabilizing properties characteristic of all class I agents
class Ib agents have less of an effect on inhibition of Na+ influx during phase 0 of the fast sodium channel action potential than do class 1a agents or class 1c agents
class Ib agents slow conduction in diseased tissue & shorten repolarization^[2]
proarrhythmic effects are less common with class Ib agents than with class Ia agents or class III agents

↑ Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 150, 155
↑ ^2.0 ^2.1 ^2.2 Medical Knowledge Self Assessment Program (MKSAP) 15, 16. American College of Physicians, Philadelphia 2009, 2012