competitive displacement, the tendency of one drug to displace another at nonspecific protein-binding sites (e.g., plasma albumin) when both drugs are taken at the same time. Only free drug is able to bind to its specific target proteins. An example is phenylbutazone, which has a greater affinity for binding sites on plasma proteins than warfarin. As a result, if both drugs are taken at the same time, fewer binding sites are available for warfarin, thereby increasing its free concentration in the plasma and increasing its anticoagulant action in the liver to potentially undesirable levels.
