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Clinical data
Trade names Ethmozine
Synonyms Moricizine (USAN US)
AHFS/ Consumer Drug Information
MedlinePlus a601214
ATC code
Pharmacokinetic data
Bioavailability 34–38%
Protein binding 95%
Elimination half-life 3–4 hours (healthy volunteers), 6–13 hours (cardiac disease)
CAS Number
PubChem CID
ECHA InfoCard 100.046.216 Edit this at Wikidata
Chemical and physical data
Formula C22H25N3O4S
Molar mass 427.518 g/mol
3D model (JSmol)
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Moracizine[1] or moricizine and 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It was used for the prophylaxis and treatment of serious and life-threatening ventricular arrhythmias,[3] but was withdrawn in 2007 for commercial reasons.[4]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]


  1. ^ "The use of stems in the selection of International Nonproprietary Names (INN) for pharmaceutical substances" (PDF). World Health Organization. 2009. p. 103. 
  2. ^ Ahmmed, G. U.; Hisatome, I.; Kurata, Y.; Makita, N.; Tanaka, Y.; Tanaka, H.; Okamura, T.; Sonoyama, K.; Furuse, Y.; Kato, M.; Yamamoto, Y.; Ogura, K.; Shimoyama, M.; Miake, J.; Sasaki, N.; Ogino, K.; Igawa, O.; Yoshida, A.; Shigemasa, C. (2002). "Analysis of moricizine block of sodium current in isolated guinea-pig atrial myocytes. Atrioventricular difference of moricizine block". Vascular Pharmacology. 38 (3): 131–141. doi:10.1016/S1537-1891(02)00213-6. PMID 12402511. 
  3. ^ British National Formulary (59th ed.). British Medical Journal Publishing Group, Pharmaceutical Press. 2010. 
  4. ^ "Shire Announces Ethmozine will be Available until December 31, 2007". Heart Rhythm Society. 
  5. ^ Cardiac Arrhythmia Suppression Trial II Investigators (1992). "Effect of the Antiarrhythmic Agent Moricizine on Survival after Myocardial Infarction". New England Journal of Medicine. 327 (4): 227–233. doi:10.1056/NEJM199207233270403. PMID 1377359.