In regard to the recent article by Singla et al .1concerning the neurokinin-1 receptor antagonist casopitant, I have a number of concerns. It is not surprising that casopitant with ondansetron was superior to ondansetron alone; this certainly would not be a proof of efficacy unless one could compare ondansetron alone with casopitant alone. If the authors had any questions regarding the efficacy of this drug, I am very curious as to why they decided not to analyze the data of the casopitant-alone arm. Because the authors did explain why their study did not include a placebo-only arm, I believe that they also owe an explanation for why the casopitant-only arm was not included in the efficacy analysis. I do not believe that there are enough data on casopitant for the authors to assume primary efficacy of this drug and move on to look only at its efficacy when combined with a second drug. If the study's primary purpose was dose finding for the prevention of postoperative emesis in the first 24 h, it is concerning that the only data analyzed were the data where casopitant was given with another antiemetic.

Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.

Singla NK, Singla SK, Chung F, Kutsogiannis DJ, Blackburn L, Lane SR, Levin J, Johnson B, Pergolizzi JV Jr: Phase II study to evaluate the safety and efficacy of the oral neurokinin-1 receptor antagonist casopitant (GW679769) administered with ondansetron for the prevention of postoperative and postdischarge nausea and vomiting in high-risk patients. Anesthesiology 2010;113:74–82