Pharmacokinetics of Tramadol and Celecoxib in Japanese and Caucasian Subjects Following Administration of Co-Crystal of Tramadol-Celecoxib (CTC): A Randomised, Open-Label Study

BACKGROUND AND OBJECTIVES: Co-Crystal of Tramadol-Celecoxib (CTC) is a first-in-class active pharmaceutical ingredient (API-API) co-crystal of rac-tramadol.HCl and celecoxib in a 1:1 molecular ratio (100 mg CTC: 44 mg rac-tramadol.HCl and 56 mg celecoxib). Tramadol and celecoxib pharmacokinetics are modified after CTC administration versus administration of reference products. This randomised, open-label, crossover, phase 1 study assessed CTC pharmacokinetics, dose proportionality, safety and tolerability in Japanese and Caucasian subjects. METHODS: ) were evaluated. Dose proportionality was assessed in a dose-adjusted bioavailability analysis of variance and in a power model. Inter-cohort comparability of pharmacokinetic exposure was confirmed if the ratio (Japanese cohort/Caucasian cohort) of geometric least-squares means and corresponding 90% confidence intervals were 80-125%. Post hoc weight-adjusted comparability analyses were performed. Safety was assessed throughout. RESULTS: Sixty subjects (21 males/9 females per cohort) were randomised; 57 completed the study. Cohorts were age and BMI matched; there were expected inter-cohort weight differences. Exposure to each analyte increased in both cohorts with increasing CTC dose. Tramadol's pharmacokinetic exposure was comparable between cohorts after adjusting for body weight; the pharmacokinetic exposure of O-desmethyltramadol and celecoxib was increased in Japanese subjects. CONCLUSIONS: Differences in pharmacokinetics were not sufficient to suggest that CTC dose adjustment is required in Japanese subjects. CLINICAL TRIAL REGISTRATION: EudraCT: 2015-003071-29.