title: The binding of acetaminophen, lidocaine, and valproic acid to human milk.
abstract: The binding of acetaminophen, lidocaine, and valproic acid to pooled normal mature human milk was studied in vitro by using equilibrium dialysis. Scatchard analysis revealed high-affinity, low-capacity binding for acetaminophen (Ka [affinity constant of association], 1.47 x 10(4) L/mol; Bo [concentration of binding sites], 9.01 x 10(-4) mol/L) and some minimal, nonspecific binding. Binding ranged up to 85%. For lidocaine, low-affinity, high-capacity binding was noted (Ka, 1.42 x 10(2) L/mol; Bo, 1.69 x 10(-2) mol/L). Binding ranged up to 72%. For valproic acid, only minimal, nonspecific binding was noted at low drug concentrations with binding ranging up to 64%. The binding of these drugs to milk might enhance their excretion and subsequent ingestion by infants who are breast-fed. In addition, the low pH of the milk (6.24) may cause "ion trapping" of acetaminophen (pKa, 9.5) and lidocaine (pKa, 7.9).
authors.affiliation: Department of Pathology, University of California, San Diego 92103-8320, USA.
authors.forename: David N
authors.initials: DN
authors.lastname: Bailey
authors.forename: John R
authors.initials: JR
authors.lastname: Briggs
mesh_terms: D000082:Acetaminophen / Q000378:metabolism*; D018712:Analgesics, Non-Narcotic / Q000378:metabolism*; D000779:Anesthetics, Local / Q000378:metabolism*; D000927:Anticonvulsants / Q000378:metabolism*; D005260:Female; D006801:Humans; D008012:Lidocaine / Q000378:metabolism*; D008895:Milk, Human / Q000378:metabolism*; D014635:Valproic Acid / Q000378:metabolism*
chemical_list: D018712:Analgesics, Non-Narcotic; D000779:Anesthetics, Local; D000927:Anticonvulsants; D000082:Acetaminophen; D014635:Valproic Acid; D008012:Lidocaine