COCAINE AND COCAETHYLENE BINDING IN HUMAN SERUM

The binding of cocaine (COG) and cocaethylene (CE) in human serum was studied by equilibrium dialysis. Scatchard analysis suggested a high-a ffinity binder(K-a, 2.56 X 10(4) L/mol; B-o, 7.38 X 10(-5) mol/L) and a low-affinity binder (K-a, 4.47 X 10(3) L/mol; B-o, 2.77 X 10(-4) mol /L) for COG. Two high-affinity binders (K-a, 5.21 X 10(4) L/mol; B-o, 2.54 X 10(-5) mol/L; and K-a, 4.32 X 10(4) L/mol; B-o, 2.43 X 10(-5) m ol/L) were discernible for CE. For both compounds additional, very-low -affinity, high-capacity (nonspecific) binding was also seen. Suppleme ntation of serum with specific proteins suggested that the high-affini ty binding was due to alpha-1-acid glycoprotein, whereas the low-affin ity binding was due to albumin, inasmuch as such supplementation incre ased the ratio of bound to free drug for both COC and CE.