Establishment of an Integrated Population Pharmacokinetic/Pharmacodynamics Model of Apixaban in Chinese Healthy Population Adjusting for Key Genetic Variants.

Aims: To improve the understanding of pharmacokinetic/pharmacodynamic (PK/PD) profiles of apixaban, supporting personalised drug prescriptions for future patients.

Background: Genetic as well as nongenetic factors can affect the predictable PK and PD characteristics of apixaban.

Objective: Establish a integrated popPK/PD model that adjusts for critical genetic variant.

Methods: The integrated PK/PD models was characterized on the basis of PK (apixaban blood concentration) and PD (prothrombin time (PT), activated partial thromboplastin time (APTT), and anti-FXa activity) data from 181 healthy Chinese volunteers. Other investigated covariate variables included: Meaningful intrinsic and extraneous determinants, correlated markers (ABCG2, F13A1, C3, etc.). A total of 2877 PK concentration observations were included in the modeling dataset.

Results: The PK model of apixaban is adopted by single compartment model with first-order oral absorption. The estimated values of total clearance rate (CL/F), apparent distribution volume (V/F), and absorption rate constant (KA) in the final model are 3.37 l/h, 28.2 l, and 0.781 l/h, respectively. The PK model includes significance covariates such as FOOD, RBC, WT, and gene (ABCG2). The PD model of apixaban is adopted by a linear direct effect model with additive error, which was used to describe the relationship between markers such as APTT, PT, anti-FXa, versus plasma concentration. PK simulation within the modelled dose range is similar to clinical real date, while PD simulation results also show that the simulated exposure parameters is within the range of the literature.

Conclusion: We established a comprehensive PK/PD model and used it to simulate markers level such as APTT, PT, and anti-FXa of apixaban. Individual predictive values with a dose of 2.5 mg are basically within the expected recommended range.