title: Fentanyl and alfentanil plasma protein binding in preterm and term neonates.
abstract: The effects of gestational age (GA) and plasma protein concentrations on the plasma protein binding of fentanyl and alfentanil were studied in preterm and term neonates. Binding experiments were performed using split-cell equilibrium dialysis. Fentanyl and alfentanil concentrations were measured using specific radioimmunoassay, and the proteins albumin and alpha-1-acid glycoprotein (AAG) were measured using radial immunodiffusion assays. In the preterm neonates, 77% of fentanyl and 65% of alfentanil was bound. In the term neonates, 70% of fentanyl and 79% of alfentanil was bound. The binding ratio of alfentanil showed a positive correlation with gestational age and AAG concentration. The binding ratio of fentanyl showed a weak, negative correlation with gestational age. These data indicate that fentanyl and alfentanil are not interchangeable at the GA studied because of age-related changes in protein binding.
authors.affiliation: Department of Anesthesiology, Children's Hospital of Pittsburgh, PA 15213-2583, USA.
authors.forename: A S
authors.initials: AS
authors.lastname: Wilson
authors.forename: R L
authors.initials: RL
authors.lastname: Stiller
authors.forename: P J
authors.initials: PJ
authors.lastname: Davis
authors.forename: G
authors.initials: G
authors.lastname: Fedel
authors.forename: S
authors.initials: S
authors.lastname: Chakravorti
authors.forename: B A
authors.initials: BA
authors.lastname: Israel
authors.forename: F X
authors.initials: FX
authors.lastname: McGowan
mesh_terms: D015760:Alfentanil / Q000378:metabolism*; D000701:Analgesics, Opioid / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism*; D005283:Fentanyl / Q000378:metabolism*; D005865:Gestational Age; D006801:Humans; D005779:Immunodiffusion; D066298:In Vitro Techniques; D007231:Infant, Newborn / Q000097:blood*; D007234:Infant, Premature / Q000097:blood*; D009961:Orosomucoid / Q000032:analysis; D011485:Protein Binding; D011863:Radioimmunoassay; D012709:Serum Albumin / Q000032:analysis
chemical_list: D000701:Analgesics, Opioid; D001798:Blood Proteins; D009961:Orosomucoid; D012709:Serum Albumin; D015760:Alfentanil; D005283:Fentanyl