The association between intravenous haloperidol and prolonged QT interval

Although intravenous haloperidol (HAL) is an effective medication that is o ften prescribed to treat agitation, several instances of torsade de pointes or prolonged QT interval have been reported. To investigate the associatio n between intravenous HAL and QT prolongation and between intravenous HAL a nd ventricular tachyarrhythmia, a cross-sectional cohort study was performe d that included measuring corrected QT intervals (QTc) on an emergency basi s before intravenous HAL and continuously monitoring electrocardiographic ( ECG) findings after intravenous HAL, During a a-month period, 47 patients r eceived intravenous injections to control psychotic disruptive behavior. Ac cording to clinical practice, patients were divided as follows. The FZ-alon e group was treated with intravenous flunitrazepam (FZ), and the FZ-plus-HA L group received intravenous FZ followed by intravenous HAL, Although the d ifference in the mean QTc immediately after intravenous FZ between the two groups was not significant, the mean QTc after 8 hours in the FZ-plus-HAL g roup was longer than that in the FZ-alone group (p < 0.001), Four patients in the FZ-plus-HAL group had a QTc of more than 500 msec after 8 hours. The change in QTc during 8 hours significantly differed between the two groups (t = 2.64,p > 0.05), Furthermore, the change in QTc was moderately correla ted with the dose of intravenous HAL, as evidenced by a coefficient of corr elation of 0.48 (p < 0.001), However, ventricular tachyarrhythmia was not d etected among 307 patients within a 1-year period, although the ECG was con tinuously monitored for at least 8 hours after intravenous HAL, The modest nature of QTc prolongation and the apparent absence of ventricular tachyarr hythmia under continuous ECG monitoring indicate that QTc prolongation asso ciated with intravenous HAL is not necessarily dangerous. However, in an em ergency situation, clinicians cannot exclude patients predisposed to torsad e de pointes, such as those with inherited ion channel disorders. Therefore , clinicians should be aware of the association between intravenous HAL and QT prolongation.