Used primarily as a metabolite of the antiarrhythmic drug amiodarone, monoiodoamiodarone retains biological activity and contributes to the prolonged effects of amiodarone in treating cardiac arrhythmias. It helps maintain rhythm control in patients with ventricular and supraventricular arrhythmias. Due to its lipophilic nature, it accumulates in tissues and provides a sustained release effect, which supports long-term management of irregular heart rhythms. Its presence in the bloodstream is monitored in patients on amiodarone therapy to assess drug metabolism and potential toxicity, especially in those with liver or thyroid dysfunction.