Moracizine[1] or moricizine, sold under the trade name Ethmozine, is an antiarrhythmic of class IC.[2] It was used for the prophylaxis and treatment of serious and life-threatening ventricular arrhythmias,[3] but was withdrawn in 2007 for commercial reasons.[4]
Moracizine, a phenothiazine derivative, undergoes extensive first-pass metabolism and is also extensively metabolized after it has entered the circulation. It may have pharmacologically active metabolites. A clinical study has shown that moracizine is slightly less effective than encainide or flecainide in suppressing ventricular premature depolarizations.[citation needed] Compared with disopyramide and quinidine, moracizine was equally or more effective in suppressing premature ventricular contractions, couplets, and nonsustained ventricular tachycardia.[citation needed]
In the Cardiac Arrhythmia Suppression Trial (CAST), a large study testing the influence of antiarrhythmics on mortality, showed a statistically non-significant increase of mortality from 5.4 to 7.2% under moracizine. This is in line with other class IC antiarrhythmics.[5]
The reaction between N-phenyl-1,3-benzenediamine (1) and ethyl chloroformate (2) gives the carbamate (3). Treatment with sulfur and iodine forms the phenothiazine derivative (4). Amide formation with 3-chloropropionyl chloride (5) gives the penultimate intermediate (6). Alkylation of morpholine by nucleophilic substitution at the sidechain chlorine yields moricizine.[6][7]