{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,14]],"date-time":"2026-09-14T06:03:51Z","timestamp":1789365831082,"version":"build-2803163510"},"reference-count":31,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,14]],"date-time":"2026-09-14T00:00:00Z","timestamp":1789344000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Pharmacol."],"abstract":"<jats:p>\n                    Tacrolimus trough concentration (C0) serves as a surrogate for drug exposure, but perioperative factors may disrupt this relationship early post-transplantation. We assessed whether the morning trough concentration (C0) on the day of kidney transplantation (POD0) accurately reflects 12-h tacrolimus exposure compared with a relatively stable early reference (POD7). We then derived the POD0 C0 corresponding to the same exposure as the conventional POD7 reference (a C0 of 7\u20139\u00a0ng\/mL). We prospectively enrolled 80\n                    <jats:italic>de novo<\/jats:italic>\n                    kidney transplant recipients receiving immediate-release tacrolimus and performed intensive pharmacokinetic sampling on POD0 (C0, C2, C3, C4, C10) and POD7 (C0, C2, C8). Dose-time-anchored AUC0-12 was calculated using the linear trapezoidal rule. The POD0 C0 corresponding to the POD7 reference AUC0-12 was derived by inverting linear, power, and median quantile regression models. Despite only a modest difference in morning C0 values (POD0 median 7.15 vs. POD7 6.40\u00a0ng\/mL), the POD0 AUC0-12 was substantially higher than that on POD7 (138.9 vs. 105.4\u00a0ng\u00b7h\/mL, p &amp;lt; 0.001); after adjustment for trough concentration, this difference was attenuated but remained significant (approximately +18% at a matched C0). Additionally, the C0\u2013AUC slope on POD0 was approximately 30% lower than on POD7 (12.0 vs. 17.1 per 1\u00a0ng\/mL). The POD7 reference AUC (125 [IQR 112\u2013144] ng\u00b7h\/mL at C0 7\u20139\u00a0ng\/mL) corresponded on POD0 to a C0 of approximately 6.8\u00a0ng\/mL (the robust quantile estimate; 5.5\u20136.8\u00a0ng\/mL across the three models). Trough C0 levels underestimated tacrolimus exposure on the day of kidney transplantation. On POD0, a trough of approximately 6\u20138\u00a0ng\/mL corresponded to an AUC0-12\u00a0at or above this relatively stable early reference. These findings are hypothesis-generating and indicate that troughs need not be driven high early to achieve adequate exposure.\n                  <\/jats:p>","DOI":"10.3389\/fphar.2026.1939477","type":"journal-article","created":{"date-parts":[[2026,9,14]],"date-time":"2026-09-14T05:38:22Z","timestamp":1789364302000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Discordance between trough concentration and tacrolimus exposure on the day of kidney transplantation: a prospective pharmacokinetic study"],"prefix":"10.3389","volume":"17","author":[{"given":"Hye Eun","family":"Kwon","sequence":"first","affiliation":[{"name":"Division of Kidney and Pancreas Transplantation, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jin-Myung","family":"Kim","sequence":"additional","affiliation":[{"name":"Division of Kidney and Pancreas Transplantation, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Youngmin","family":"Ko","sequence":"additional","affiliation":[{"name":"Division of Kidney and Pancreas Transplantation, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sung","family":"Shin","sequence":"additional","affiliation":[{"name":"Division of Kidney and Pancreas Transplantation, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Young Hoon","family":"Kim","sequence":"additional","affiliation":[{"name":"Division of Kidney and Pancreas Transplantation, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joo Hee","family":"Jung","sequence":"additional","affiliation":[{"name":"Division of Kidney and Pancreas Transplantation, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chung Hee","family":"Baek","sequence":"additional","affiliation":[{"name":"Division of Nephrology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hyosang","family":"Kim","sequence":"additional","affiliation":[{"name":"Division of Nephrology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hyunwook","family":"Kwon","sequence":"additional","affiliation":[{"name":"Division of Kidney and Pancreas Transplantation, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,9,14]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"2825","DOI":"10.1111\/j.1600-6143.2012.04174.x","article-title":"A randomized pharmacokinetic study of generic tacrolimus versus reference tacrolimus in kidney transplant recipients","volume":"12","author":"Alloway","year":"2012","journal-title":"Am. 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