title: Development of a physiologically based model to describe the pharmacokinetics of methylphenidate in juvenile and adult humans and nonhuman primates.
abstract: The widespread usage of methylphenidate (MPH) in the pediatric population has received considerable attention due to its potential effect on child development. For the first time a physiologically based pharmacokinetic (PBPK) model has been developed in juvenile and adult humans and nonhuman primates to quantitatively evaluate species- and age-dependent enantiomer specific pharmacokinetics of MPH and its primary metabolite ritalinic acid. The PBPK model was first calibrated in adult humans using in vitro enzyme kinetic data of MPH enantiomers, together with plasma and urine pharmacokinetic data with MPH in adult humans. Metabolism of MPH in the small intestine was assumed to account for the low oral bioavailability of MPH. Due to lack of information, model development for children and juvenile and adult nonhuman primates primarily relied on intra- and interspecies extrapolation using allometric scaling. The juvenile monkeys appear to metabolize MPH more rapidly than adult monkeys and humans, both adults and children. Model prediction performance is comparable between juvenile monkeys and children, with average root mean squared error values of 4.1 and 2.1, providing scientific basis for interspecies extrapolation of toxicity findings. Model estimated human equivalent doses in children that achieve similar internal dose metrics to those associated with pubertal delays in juvenile monkeys were found to be close to the therapeutic doses of MPH used in pediatric patients. This computational analysis suggests that continued pharmacovigilance assessment is prudent for the safe use of MPH.
authors.affiliation: National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, United States of America.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Yang
authors.affiliation: National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, United States of America.
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Morris
authors.affiliation: The Henry M. Jackson Foundation for the Advancement of Military Medicine, Wright-Patterson Air Force Base, Ohio, United States of America.
authors.forename: Jeffery M
authors.initials: JM
authors.lastname: Gearhart
authors.affiliation: The Henry M. Jackson Foundation for the Advancement of Military Medicine, Wright-Patterson Air Force Base, Ohio, United States of America.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Ruark
authors.affiliation: National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, United States of America.
authors.forename: Merle G
authors.initials: MG
authors.lastname: Paule
authors.affiliation: National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, United States of America.
authors.forename: William
authors.initials: W
authors.lastname: Slikker
authors.affiliation: Risk Sciences International, Ottawa, Ontario, Canada; University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Mattison
authors.affiliation: National Institute of Mental Health, Bethesda, Maryland, United States of America.
authors.forename: Benedetto
authors.initials: B
authors.lastname: Vitiello
authors.affiliation: National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, United States of America.
authors.forename: Nathan C
authors.initials: NC
authors.lastname: Twaddle
authors.affiliation: National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, United States of America.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Doerge
authors.affiliation: National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, United States of America.
authors.forename: John F
authors.initials: JF
authors.lastname: Young
authors.affiliation: National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, United States of America.
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Fisher
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000818:Animals; D001682:Biological Availability; D001711:Biotransformation; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D000697:Central Nervous System Stimulants / Q000097:blood / Q000493:pharmacokinetics*; D002648:Child; D006066:Gonads / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008253:Macaca mulatta; D008297:Male; D008774:Methylphenidate / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics*; D008954:Models, Biological; D015233:Models, Statistical; D009206:Myocardium / Q000378:metabolism
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate; C009189:ritalinic acid