Small doses of droperidol do not present relevant torsadogenic actions: a double-blind, ondansetron-controlled study

Drugs used for postoperative nausea and vomiting prophylaxis are believed to provoke torsadogenic changes in cardiac repolarization. The aim of this study was to assess the effect of small doses of droperidol on the parameters of cardiac repolarization, including the QTc interval and transmural dispersion of repolarization.

A total of 75 patients were randomly allocated to receive 0.625 or 1.25 mg droperidol or 8 mg ondansetron. The QTc interval was calculated using Bazett's formula and the Framingham correction. The transmural dispersion of repolarization was determined as Tpeak -Tend time.

Transient QT prolongation, corrected with both formulae, followed 1.25 mg of droperidol 10 min after administration. No change in the QTc value was observed in the other groups. When corrected with Bazett's formula, QTc was prolonged above 480 ms in two patients receiving 1.25 mg droperidol (at the 10(th) and 20(th) minute of the study) and in one receiving ondansetron. No patients developed a QTc B prolongation over 500 ms. No increase above 480 ms was observed relative to the Framingham correction method. There were no significant differences in the Tpeak -Tend time either between or within the groups.

In men without cardiovascular disorders small doses (1.25 mg) of droperidol prophylaxis induced transient QTc prolongation without changes in transmural dispersion of repolarization. The apparently low risk of the drug applies only in low risk male patients with a low pro-QTc score.