Proarrhythmic effect and underlying mechanism of combined use of azithromycin and Shengmai injection in guinea pigs / 中国药理学与毒理学杂志

ABSTRACT

OBJECTIVE To explore potential proarrhythmic effect and underlying mechanism of azithromycin (AZM) and Shengmai injection (SM) used clinically.METHODS ① In vivo guinea pig ECG recordings were made to analyze effects of jugular intravenous(iv) injection of AZM [38.2 mg· kg-1,one time (clinically relevant dose,CRD)],or SM (4.6 mL· kg-1,one time CRD) or their combination.②In vitro ECG recordings were made to analyze effects of AZM,SM or AZM + SM on ECG in isolated hearts of guinea pigs.AZM [one,five and ten times (clinically relevant concentrations,CRC)] was perfused in this order41.5 →207.5 → 415 mg· L-1 and SM (one,five and ten times CRC) in this order5 →25 →50 mL· L-1.Also,AZM (41.5 mg· L-1,one time CRC) +SM (5 mL· L-1,one time CRC) was perfused to isolated hearts of guinea pigs.③ Enzymatically isolated cardiomyocytes from guinea pig left ventricles were perfused in this orderAZM 41.5 mg· L-1 →AZM 41.5 mg· L-1+SM 5 mL· L-1 for action potential,L-type Ca2+ and Na+ current recordings,respectively.RESULTS ① Neither AZM 38.2 mg· kg-1,nor SM 4.6 mL· kg-1 significantly changed the in vivo ECG.However,AZM 38.2 mg· kg-1 +SM 4.6 mL · kg-1 significantly reduced heart rate (P＜0.05) and prolonged the P-R (P＜0.05) and QRS (P＜0.05) intervals.②AZM 41.5,207.5 and 415 mg· L-1 reduced heart rate (P＜0.05) and prolonged the P-R (P＜0.05) and QRS (P＜0.05) intervals in a concentration-dependent manner.AZM 415 mg·L-1 also prolonged QTc (P＜0.05) interval.SM 5,25 and 50 mL· L-1 reduced heart rate (P＜0.05) and prolonged the P-R interval (P＜0.05) in a concentration-dependent manner.SM had no effect on QRS or QTc intervals.Washout partially recovered the above changes.Moreover,AZM 41.5 mg· L-1 + SM 5 mg·L-1 significantly reduced heart rate (P＜0.05) and prolonged the P-R (P＜0.05) and QRS intervals.③ AZM 41.5 mg·L-1 did not significantly change the action potential amplitude (APA),action potential durations at 50％ (APD50) and 90％ (APD90) repolarization levels,or L-type Ca2+ and Na+ currents.However,AZM+SM 5 mg· L-1 significantly reduced APA (P＜0.05),shortened APD50 (P＜0.05) and APD90 (P＜0.05) and inhibited the L-type Ca2+ (P＜0.05) and Na+ (P＜0.05) currents.CONCLUSION AZM and SM has potential prorrhythmic risks.The combined use might cause higher risk of arrhythmia.The underlying mechanism for proarrhythmia is mediated by inhibition of the L-type Ca2+ and Na+ currents.