Comparative Pharmacokinetics of Two Extended‐Release Tablet Formulations of Upadacitinib: Bioequivalence Assessment

Abstract The aim of this study is to evaluate the pharmacokinetic characteristics, bioequivalence, and safety of two brands of upadacitinib (UPA) extended‐release tablets (15 mg) in healthy Chinese subjects under fasting and postprandial conditions. The plasma concentration of UPA was determined by ultra‐high‐performance liquid chromatography‐tandem mass spectrometry, and pharmacokinetic parameters were calculated using a non‐compartmental model (NCA module) with Phoenix WinNonlin 8.2 (Certara, USA) software, followed by bioequivalence evaluation. The results demonstrate that the 90% confidence intervals for the geometric least‐squares mean ratios of C max , AUC 0–t , and AUC 0–∞ between the test and reference formulations fall within the range of 0.80−1.25, indicating that both formulations are bioequivalent in terms of absorption rate and extent under fasting and postprandial conditions. No serious adverse events occurred, and observed drug‐related adverse events were mild under both conditions, indicating comparable safety of the two formulations.