A single-dose, randomized, open-label, four-period, crossover equivalence trial comparing the clinical similarity of the proposed biosimilar rupatadine fumarate to reference Wystamm® in healthy Chinese subjects

Purpose: The aim of this study was to evaluate the bioequivalence of two formulations of rupatadine (10-mg tablets) under fasting and fed conditions in healthy Chinese subjects. Methods: A total of 72 subjects were randomly assigned to the fasting cohort (n = 36) and fed cohort (n = 36). Each cohort includes four single-dose observation periods and 7-day washout intervals. Blood samples were collected at several timepoints for up to 72 h post-dose. The plasma concentration of rupatadine and the major active metabolites (desloratadine and 3-hydroxydesloratadine) were analyzed by a validated HPLC-MS/MS method. The non-compartmental analysis method was employed to determine the pharmacokinetic parameters. Based on the within-subject standard deviation of the reference formulation, a reference-scaled average bioequivalence or average bioequivalence method was used to evaluate the bioequivalence of the two formulations. Results: For the fasting status, the reference-scaled average bioequivalence method was used to evaluate the bioequivalence of the maximum observed rupatadine concentration (C-max; subject standard deviation > 0.294), while the average bioequivalence method was used to evaluate the bioequivalence of the area under the rupatadine concentration-time curve from time 0 to the last detectable concentration (AUC(0-t)) and from time 0 to infinity (AUC(0-infinity)). The geometric mean ratio (GMR) of the test/reference for C-max was 95.91%, and the upper bound of the 95% confidence interval was 95.91%. For AUC(0-t) and AUC(0-infinity) comparisons, the GMR and 90% confidence interval (CI) were 98.76% (93.88%-103.90%) and 98.71% (93.93%-103.75%), respectively. For the fed status, the subject standard deviation values of C-max, AUC(0-t), and AUC(0-infinity) were all <0.294; therefore, the average bioequivalence method was used. The GMR and 90% CI for C-max, AUC(0-t), and AUC(0-infinity) were 101.19% (91.64%-111.74%), 98.80% (94.47%-103.33%), and 98.63% (94.42%-103.03%), respectively. The two-sided 90% CI of the GMR for primary pharmacokinetic endpoints of desloratadine and 3-hydroxydesloratadine was also within 80%-125% for each cohort. These results met the bioequivalence criteria for highly variable drugs. All adverse events (AEs) were mild and transient. Conclusion: The test drug rupatadine fumarate showed a similar safety profile to the reference drug Wystamm (R) (J. Uriach y Compa & ntilde;& iacute;a, S.A., Spain), and its pharmacokinetic bioequivalence was confirmed in healthy Chinese subjects based on fasting and postprandial status.