<prompt> Which of the following drugs should not be administered concomitantly with warfarin as it decreases the effect of oral anticoagulantsBroad spectrum antibioticCimetidineAspirinOral contraceptive  <response>: Oral contraceptives Estrogen increases the synthesis of various clotting factors and produce a hypercoagulable state. Thus OCP containing estrogen decrease the effectiveness of warfarin and other oral anticoagulants. 