title: Receptor-mediated pharmacokinetics and pharmacodynamics of interferon-beta1a in monkeys.
abstract: A pharmacokinetic/pharmacodynamic (PK/PD) model was developed to simultaneously characterize interferon after i.v. and s.c. dosing at various dose levels. A sequential study in monkeys (n = 18) was conducted, where single doses of 1, 3, and 10 MIU/kg of recombinant-human interferon-beta (IFN-beta) 1a were given i.v. and then s.c. Plasma concentrations of IFN-beta were determined and biphasic neopterin concentrations were used as the pharmacodynamic (PD) endpoint. Multiple dosing also was evaluated by giving 1 MIU/kg s.c. doses once daily for 7 days (n = 3). The integrated model uses target-mediated drug disposition to describe drug elimination by receptor binding and internalization, and well characterizes the observed nonlinear pharmacokinetic (PK) profiles. The s.c. doses exhibited an absorption phase (Tmax = 3 h) and incomplete bioavailability (F = 0.3-0.7). An indirect response model for stimulation of neopterin triphosphate production by activated receptor complex followed by conversion to neopterin was used to jointly model the formation and loss of neopterin with a capacity factor Smax = 23.8. Greater relative neopterin response after s.c. dosing was accounted for by prolonged receptor activation relative to the SC50 value. Repeated daily s.c. dosing produced modestly elevated IFN-beta1a concentrations and neopterin concentrations that were lower than simulated from single-dose modeling. Although several mechanisms could be involved, these phenomena were simply remodeled as down-regulation of Smax and receptors. The PK/PD model for IFN-beta1a depicts receptor binding as a key feature controlling nonlinear elimination, nonstationary kinetics, and neopterin induction in a manner consistent with known processes controlling its disposition and pharmacological effects.
authors.affiliation: Department of Pharmaceutical Sciences, University at Buffalo, State University of New York, 565 Hochstetter Hall, Buffalo, NY 14260, USA.
authors.forename: Donald E
authors.initials: DE
authors.lastname: Mager
authors.forename: Berend
authors.initials: B
authors.lastname: Neuteboom
authors.forename: Constantinos
authors.initials: C
authors.lastname: Efthymiopoulos
authors.forename: Alain
authors.initials: A
authors.lastname: Munafo
authors.forename: William J
authors.initials: WJ
authors.lastname: Jusko
mesh_terms: D000818:Animals; D001682:Biological Availability; D004305:Dose-Response Relationship, Drug; D005260:Female; D000068556:Interferon beta-1a; D016899:Interferon-beta / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology; D008252:Macaca fascicularis; D008297:Male; D019798:Neopterin / Q000378:metabolism
chemical_list: D019798:Neopterin; D016899:Interferon-beta; D000068556:Interferon beta-1a