title: Arginine behaviour after arginine or citrulline administration in older subjects.
abstract: Arginine (ARG) and its precursor citrulline (CIT) are popular dietary supplements, especially for the elderly. However, age-related reductions in lean body mass and alterations in organ functions could change their bioavailability. Pharmacokinetics and tolerance to amino acid (AA) loads are poorly documented in elderly subjects. The objective here was to characterise the plasma kinetics of CIT and ARG in a single-dosing study design. Eight fasting elderly men underwent two separate isomolar oral loading tests (10 g of CIT or 9·94 g of ARG). Blood was withdrawn over an 8-h period to measure plasma AA concentrations. Only CIT, ornithine and ARG plasma concentrations were changed. Volume of distribution was not dependent on AA administered. Conversely, parameters related to ARG kinetics were strongly dependent on AA administered: after ARG load, elimination was higher (ARG>CIT; P=0·041) and admission period+time at peak concentration was lower (ARG<CIT; P=0·033), and the combination of both phenomena results in a marked increase in ARG availability when CIT was administered (ARG<CIT; P=0·033) compared with ARG administration itself. In conclusion, a single CIT administration in the elderly is safe and well tolerated, and CIT proves to be a better in vivo ARG precursor than ARG itself in healthy elderly subjects.
authors.affiliation: 1Laboratoire de Biologie de la Nutrition EA 4466,Faculté des Sciences Pharmaceutiques et Biologiques de l'Université Paris Descartes,4 avenue de l'Observatoire,75270 Paris Cedex 06,France.
authors.forename: C
authors.initials: C
authors.lastname: Moinard
authors.affiliation: 2Laboratoire de Biomathématiques, Faculté de Pharmacie,Université Paris Descartes,Paris,75006,France.
authors.forename: J
authors.initials: J
authors.lastname: Maccario
authors.affiliation: 3UMR1019 Métabolisme protéino-énergétique,INRA,Université Clermont 1,Clermont-Ferrand,63001,France.
authors.forename: S
authors.initials: S
authors.lastname: Walrand
authors.affiliation: 2Laboratoire de Biomathématiques, Faculté de Pharmacie,Université Paris Descartes,Paris,75006,France.
authors.forename: V
authors.initials: V
authors.lastname: Lasserre
authors.affiliation: 1Laboratoire de Biologie de la Nutrition EA 4466,Faculté des Sciences Pharmaceutiques et Biologiques de l'Université Paris Descartes,4 avenue de l'Observatoire,75270 Paris Cedex 06,France.
authors.forename: J
authors.initials: J
authors.lastname: Marc
authors.affiliation: 3UMR1019 Métabolisme protéino-énergétique,INRA,Université Clermont 1,Clermont-Ferrand,63001,France.
authors.forename: Y
authors.initials: Y
authors.lastname: Boirie
authors.affiliation: 1Laboratoire de Biologie de la Nutrition EA 4466,Faculté des Sciences Pharmaceutiques et Biologiques de l'Université Paris Descartes,4 avenue de l'Observatoire,75270 Paris Cedex 06,France.
authors.forename: L
authors.initials: L
authors.lastname: Cynober
mesh_terms: D000368:Aged; D000596:Amino Acids / Q000097:blood; D001120:Arginine / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D015992:Body Mass Index; D002956:Citrulline / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D019587:Dietary Supplements; D005215:Fasting; D006801:Humans; D008297:Male; D009952:Ornithine / Q000097:blood
chemical_list: D000596:Amino Acids; D002956:Citrulline; D001120:Arginine; D009952:Ornithine
keywords: AA amino acid; ARG arginine; Amino acids; CIT citrulline; Food supplements; Ornithine; Pharmacokinetics