Perfluorochemical emulsion effect on warfarin binding by fraction V human albumin

A previous study demonstrated that a relatively large concentration of a perfluorochemical (PFC) emulsion caused significant displacement of bound warfarin from fatty acid free human albumin. To determine whether this displacement would occur when fatty acids were associated with albumin, the effect of the emulsion on warfarin binding by fraction V human albumin was examined. Binding of 2 and 10 micrograms/ml warfarin at room temperature by 4 per cent albumin solutions diluted with the emulsion was determined by centrifugation followed by supernatant ultrafiltration. Warfarin binding by identical buffer dilutions of albumin solutions served as controls. The emulsion had no effect on warfarin binding other than dilution when albumin solutions were diluted to 75 and 50% v/v. Further dilution of albumin solutions to 40, 25 and 10% v/v with blood substitute resulted in significant increases in the per cent free warfarin even though warfarin is weakly bound by the emulsion droplets. These increases in per cent free warfarin were apparently due to the displacement of albumin bound warfarin by a component(s) of the emulsion, possibly the potassium oleate component. The ability of 2 and 10 micrograms/ml warfarin to partition from pH 7.4 buffer into the purified PFC liquids was also determined at room temperature. Warfarin did not partition into the PFC liquids indicating that emulsion bound warfarin is only associated with the emulsifiers of the droplets.