Ropitoin (TR2985) is a diphenylhydantoin derivative. It is an antiarrhythmic compound that causes a depression of the maximum upstroke velocity (used as a measure of cardiac function: an indirect index of the magnitude of the sodium current). Its effect was shown in several cardiac tissues and in guinea pig muscles and dog Purkinje fibers (myocardial cells). Ropitoin is believed to bind to the same receptor site in the sodium channel as mexiletine and quinidine. In an animal study, ropitoin was shown to be ineffective in preventing reentrant ventricular tachycardia (when the electric signal fails to die out after normal activation) or ventricular fibrillation. No information on the current use of this compound is available.