Cocaine and cocaethylene binding to human milk.
The binding of cocaine and its ethyl analog, cocaethylene, to human milk was studied using equilibrium dialysis at 4 degrees C. For cocaine, a low-affinity, high-capacity binder was noted (equilibrium constant of association, Ka, 3.12 x 10(3) L/mol; concentration of binding sites, B0, 3.85 x 10(-4) mol/L), as well as a very low affinity, high-capacity binder (Ka, 7.54 x 10(2) L/mol; B0, 1.42 x 10(-3) mol/L). For cocaethylene, 2 low-affinity, high-capacity binders were suggested: a stronger (Ka, 3.79 x 10(3) L/mol; B0, 3.27 x 10(-4) mol/L) and a weaker (Ka, 1.84 x 10(3) L/mol; B0, 8.91 x 10(-4) mol/L) binder The low-affinity, high-capacity binder for cocaine and cocaethylene seems to be albumin, while the weaker nonspecific binding may be due to lipids. Up to 55% of cocaine and up to 61% of cocaethylene were bound to milk; such binding, coupled with the lower pH of milk (6.9) relative to that of serum (7.4), may enhance the mammary secretion of these 2 basic drugs, having important consequences for the nursing infant.
Department of Pathology, University of California, San Diego, USA.
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Bailey
D003042:Cocaine / Q000031:analogs & derivatives* / Q000378:metabolism*; D018765:Dopamine Uptake Inhibitors / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008895:Milk, Human / Q000378:metabolism*
D018765:Dopamine Uptake Inhibitors; C066444:cocaethylene; D003042:Cocaine