<unk>  is a medication that acts as a class I antiarrhythmic agent (Ia) in the heart. It is a stereoisomer of<unk> uinine, originally derived from the bark of the cinchona tree. The drug causes increased action potential duration, as well as a prolonged<unk> T interval. As of 2019 it is no longer being manufactured for use in the United States.
Quinidine
Lidocaine
Nortilidine
Colestilan
Ibutilide
Maprotiline
Etidocaine
Amiodarone