THE INFLUENCE OF BARBITURATES ON COUMARIN PLASMA LEVELS AND PROTHROMBIN RESPONSE*

Abstract

Wide individual variations in response to drugs is a common clinical problem, and is especially evi- dent with coumarin anticoagulant therapy (1-3). A possible contributing factor to such variations could be the influence of another presumably un- related drug upon the response to the coumarin anticoagulant. Reports from several laboratories (4-7) indicate that barbiturates can reduce the prothrombin response to coumarin anticoagulants. This report presents initial results of studies de- signed to determine the manner by which barbitu- rates alter the response to coumarins in man, guinea pig and dog.