Abstract
Binding of clopidogrel to serum albumin has been characterized in the presence and absence of linoleic acid by equilibrium dialysis method where ranitidine and diazepam were used as specific probes. Our findings suggested two binding sites for clopidogrel: a high affinity site (k(1) = 11.5 x 10(5) M-1) with low capacity (n(1) = 1.2) and low affinity site (k(2) = 2.1 x 10(5) M-1) with high capacity (n(2) = 9.3). Interaction of linoleic acid with clopidogrel in the presence of ranitidine shows an increment of clopidogrel from 71 to 85.5% at concentration of (1 x 10(-5) M) to (6 x 10(-5) M). However, interaction of linoleic acid with clopidogrel in the presence of diazepam exhibits significant rise in free fraction of clopidogrel from 93 to 116% at concentration of (0 x 10(-5) M) to (4 x 10(-5) M). At higher concentrations, linoleic acid displaced clopidogrel from its binding sites on serum albumin. This may cause escalation of free drug in the blood, which alters pharmacokinetic properties of clopidogrel taken with high fat diet.