sentences:  Its metabolic pathway is via liver's cytochrome P450 system by isoenzymes other than CYP3A4 and CYP2D6 by which the heptyl side chain of ibutilide is oxidized.With eight metabolites are detected in the urine, however, only one is an active metabolite that shares the similar electrophysiologic property of the Class III antiarrhythmic agents.The plasma concentration of this metabolite is only less than 10% of ibutilide.