Effects of palonosetron on prolongation of corrected QT intervals may be less than reliable

Min et al. [1] investigated the effects of palonosetron, a second-generation 5-hydroxytryptamine-3 receptor antagonist, on corrected QT (QTc) intervals on electrocardiograms of patients undergoing laparotomies under sevoflurane anesthesia. Considering that prolongation of the QTc interval is associated with torsades de pointes, and palonosetron may at least theoretically increase QTc intervals by similar pharmacological mechanisms as ondansetron [2], clinicians will agree that an investigation into the effects of palonosetron on QTc intervals is required. Careful consideration is, however, needed, although Min et al. [1] concluded that palonosetron may induce QTc prolongation during general anesthesia with sevoflurane.

In the present study [1], there was a significantly different factor, famotidine, which also can influence the QTc interval. Consequently, it is difficult to exclude its effect on the QTc intervals, in contrast to the authors' description. Additionally, underlying diseases, electrolyte abnormalities, other drugs, adrenergic tone, temperature, and circadian variation, have other effects that may also result in prolongation of QTc intervals [3]. All of these influences may result in QTc prolongation, diminishing the effects of palonosetron alone. Furthermore, a less well-defined target population, risk of selection bias, and confounding factors in retrospective studies may affect the results [4]. Finally, Min et al. [1] concluded that palonosetron could induce QTc prolongation during general anesthesia with sevoflurane, whereas the prospective, randomized, and double-blinded study by Kim et al. [5] showed that preanesthetic administration of palonosetron (0.075 mg) did not affect the QTc interval during the intraoperative period.

Thus, to better understand the effects of palonosetron on QTc intervals, it is essential to consider all of the factors related to QTc intervals, the weaknesses of retrospective studies, and related research results. Further well-designed studies on this issue from various perspectives will also be helpful.