Zhang J, Zhang H, Zhao L, Gu J, Feng Y, An H. Population pharmacokinetic modeling of flurbiprofen, the active metabolite of flurbiprofen axetil, in Chinese patients with postoperative pain. J Pain Res. 2018;11:3061–3070.The Editor-in-Chief and Publisher of the Journal of Pain Research wish to issue an Expression of concern for the published article.A reader raised concerns to the Editor about the validity of the data presented in the published article. It was alleged three authors of the present article, Zhang H, Feng Yand Gu J, had previously published the results of the study in the article: Zhang H, Feng Y, Gu J. Distribution of flurbiprofen axetil in cerebral-spinal fluid after intravenous administration. Chin J Anaesthesiol. 2011;31(04):432–434. doi:10.3760/cma.j.issn.0254-1416.2011.04.012.It was also alleged the clinical trial registration (CTR) number (ChiCTR-TRC-11001791) provided in the published article was taken from an unrelated study and had no association with the current study.Read the original article