Binding of clometacin to human serum albumin. Interactions with clofibrate, indomethacin, salicylic acid and warfarin.

The binding of clometacin to human serum albumin (HSA) was studied in vitro by equilibrium dialysis. Our results show that binding to HSA is 99% at therapeutic levels. Binding is characterized by several numbers of binding sites (n = 8) with a moderate association constant (K = 2.7 X 10(4) M-1) and by another non-saturable phenomenon (nK = 4200 M-1). Moreover, interactions were studied with many drugs. Clometacin binding was altered by indomethacin, warfarin, chlorophenoxyisobutyrate (CPIB) and salicylic acid (SA). Conversely, clometacin inhibited the binding of these drugs. Finally, all these results were compared with those previously obtained with indomethacin, a positional isomer of clometacin.