Systematic review of the use of intravenous amiodarone and nifekalant for cardiopulmonary resuscitation in Japan

Background Intravenous amiodarone is considered to be the first‐line drug for the treatment of ventricular tachycardia or fibrillation. However, in Japan, nifekalant had been used before the introduction of amiodarone; therefore, most clinical studies on amiodarone use have been small‐scale studies. The aim of the present study was to review the literature concerning the actual use of amiodarone and nifekalant in order to evaluate the effects of both drugs and the most appropriate mode of administration. Methods The Japan Medical Abstracts Society, PubMed, and Scopus databases were used to identify the reports. The resulting data were used for a systematic review focusing on the effectiveness of amiodarone in comparison with that of nifekalant and the dose differential effect of amiodarone. Results The search returned 9 studies, including 310 patients, that compared the effectiveness of amiodarone and nifekalant, as well as 3 studies, including 108 patients, that analyzed the effectiveness of treatment according to amiodarone dose. Of 418 patients, 187 in whom amiodarone was used for cardiopulmonary resuscitation (CPR) were included in a review that compared the doses recommended by Japanese guidelines 2009 (125 mg intravenous [i.v.] over 10 min) and the American Heart Association guidelines (300 mg bolus i.v.). Amiodarone and nifekalant were equally effective in preventing electrical storm (67% vs. 67%). The defibrillation effect for CPR was also equal in the 2 groups (60% vs. 54%). Hypotension and bradycardia were recorded as adverse effects in the amiodarone group (9.5% and 5.3%), whereas torsades de pointes was observed in the nifekalant group (1.4%). In the analysis of the dose‐differential effect of amiodarone, the rates of successful return of spontaneous circulation and discharge survival were higher in the 125‐mg slow i.v. group than in the 300‐mg bolus i.v. group (76% vs. 53% and 54% vs. 26%, respectively). Conclusions Amiodarone and nifekalant were equivalent in their prophylactic and defibrillation efficacy. Concerning the initial amiodarone dose, the 125 mg intravenous [i.v.] over 10 min seemed to be more appropriate for the Japanese population.