title: Are coagulation times biomarkers? Data from a phase I study of the oral thrombin inhibitor LB-30057 (CI-1028).
abstract: Ecarin clotting time and activated partial thromboplastin time are coagulation tests that meet the definition of a biomarker. Prolongation of these coagulation times closely correlated with blood concentrations of the oral thrombin inhibitor LB-30057 (CI-1028) during a phase 1 study. But this simply reflects their functioning as enzyme inhibition assays of drug concentration. Directly adding the drug to blood results in the same concentration-response relationship. Changes in coagulation tests only demonstrate that ex vivo clot formation has been altered, not that an in vivo process has been affected. To be most informative in drug development, biomarker assays should measure in vivo drug effects, not drug concentrations.
authors.affiliation: Experimental Medicine, Clinical Pharmacokinetics/Pharmacodynamics, and Drug Safety Evaluation Departments, Pfizer Global Research & Development, Ann Arbor, Michigan 48105, USA.
authors.forename: Ralph
authors.initials: R
authors.lastname: Stern
authors.forename: Francoise
authors.initials: F
authors.lastname: Chanoine
authors.forename: Kay
authors.initials: K
authors.lastname: Criswell
mesh_terms: D000284:Administration, Oral; D001549:Benzamides / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D015415:Biomarkers; D001777:Blood Coagulation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male
chemical_list: D001549:Benzamides; D015415:Biomarkers; C116605:LB 30057