title: Integrated population pharmacokinetics of etanercept in healthy subjects and in patients with rheumatoid arthritis and ankylosing spondylitis.
abstract: Etanercept pharmacokinetics in patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS), and psoriasis were assessed separately with distinct models using population pharmacokinetics methods of limited precision. The different model structures and associated significant covariates identified by these earlier methods made it difficult to compare etanercept pharmacokinetics among disease groups. This integrated analysis aimed to establish a framework to evaluate previously established population pharmacokinetic models of etanercept, and to identify consistent and important demographic and disease factors that affected etanercept pharmacokinetics in a diverse population of healthy subjects and patients with RA and AS. In this integrated analysis, cumulative rich and sparse etanercept concentration data from 53 healthy volunteers, 212 patients with RA, and 346 patients with AS were examined and compared using nonlinear mixed effect methodology implemented the in NONMEM VI software package. A more precise estimation method (FOCEi) was employed and compared with the first-order method in population pharmacokinetics model building and evaluation. The integrated analysis found that an optimal population pharmacokinetics model with a 2-compartment structure adequately characterized etanercept pharmacokinetics in all subject groups. Health status or disease type did not significantly affect etanercept pharmacokinetics. In adult patients with RA and AS, age and body weight do not significantly affect etanercept pharmacokinetics.
authors.affiliation: Pfizer Specialty Care Business Unit, Clinical Pharmacology, Pfizer Specialty Care Business Unit, Collegeville, PA, USA. Yuji.Zhou@pfizer.com
authors.forename: Simon Y
authors.initials: SY
authors.lastname: Zhou
authors.forename: Cathye
authors.initials: C
authors.lastname: Shu
authors.forename: Joan
authors.initials: J
authors.lastname: Korth-Bradley
authors.forename: Donald
authors.initials: D
authors.lastname: Raible
authors.forename: Maria
authors.initials: M
authors.lastname: Palmisano
authors.forename: Joseph
authors.initials: J
authors.lastname: Wadjula
authors.forename: Saeed
authors.initials: S
authors.lastname: Fatenejad
authors.forename: Thorir
authors.initials: T
authors.lastname: Bjornsson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D017321:Clinical Trials, Phase I as Topic; D017322:Clinical Trials, Phase II as Topic; D017326:Clinical Trials, Phase III as Topic; D000068800:Etanercept; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000378:metabolism*; D007166:Immunosuppressive Agents / Q000097:blood / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D018124:Receptors, Tumor Necrosis Factor / Q000097:blood / Q000378:metabolism*; D013167:Spondylitis, Ankylosing / Q000097:blood / Q000378:metabolism*
chemical_list: D007074:Immunoglobulin G; D007166:Immunosuppressive Agents; D018124:Receptors, Tumor Necrosis Factor; D000068800:Etanercept