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Are Coagulation Times Biomarkers? Data from a Phase I Study of the Oral Thrombin Inhibitor LB‐30057 (CI‐1028)
Author(s) -
Stern Ralph,
Chanoine Francoise,
Criswell Kay
Publication year - 2003
Publication title -
the journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 116
eISSN - 1552-4604
pISSN - 0091-2700
DOI - 10.1177/0091270002239818
Subject(s) - partial thromboplastin time , coagulation , in vivo , drug , pharmacology , thrombin time , ex vivo , biomarker , thrombin , thromboplastin , coagulation testing , medicine , chemistry , prothrombin time , platelet , biochemistry , biology , microbiology and biotechnology
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.