title: Oral versus intravenous administration of lysine: equal effectiveness in reduction of renal uptake of [111In-DTPA]octreotide.
abstract: During tumor therapy with radiolabeled somatostatin analogs, the kidneys are dose limiting. Renal uptake in patients can effectively be reduced by a 4- to 10-h intravenous infusion of a lysine/arginine solution, thereby increasing the maximum radiation dose to the tumor without renal side effects. Oral administration of amino acids could facilitate this labor-intensive procedure. Therefore, the effects of oral versus intravenous administration of D-lysine were compared in rats injected with [111In-diethylenetriaminepentaacetic acid (DTPA)]octreotide.
  
  
  METHODS
  Rats were intravenously injected with 3 MBq/0.5 microg [111In-DTPA]octreotide and also received D-lysine intravenously or orally in various concentrations and following various time schedules. Twenty-four hours after injection, a biodistribution study and renal ex vivo autoradiography were performed.
  
  
  RESULTS
  Renal uptake was reduced significantly-up to 40%-in all lysine-treated groups, without affecting the uptake in other organs.
  
  
  CONCLUSIONS
  Renal uptake of this radiolabeled peptide can be reduced up to 40% both by oral and by intravenous administration of lysine in rats.
authors.affiliation: Department of Nuclear Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands. s.m.verwijnen@erasmusmc.nl
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Verwijnen
authors.forename: Eric P
authors.initials: EP
authors.lastname: Krenning
authors.forename: Roelf
authors.initials: R
authors.lastname: Valkema
authors.forename: Jan G M
authors.initials: JG
authors.lastname: Huijmans
authors.forename: Marion
authors.initials: M
authors.lastname: de Jong
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001120:Arginine / Q000008:administration & dosage; D001345:Autoradiography; D004801:Eosine Yellowish-(YS) / Q000494:pharmacology; D006416:Hematoxylin / Q000494:pharmacology; D007205:Indium Radioisotopes / Q000494:pharmacology*; D007262:Infusions, Intravenous; D007668:Kidney / Q000000981:diagnostic imaging* / Q000187:drug effects* / Q000473:pathology; D008239:Lysine / Q000008:administration & dosage*; D008297:Male; D015233:Models, Statistical; D015282:Octreotide / Q000031:analogs & derivatives* / Q000494:pharmacology; D004369:Pentetic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000494:pharmacology; D051381:Rats; D011917:Rats, Inbred Lew; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: C497824:111In-octreotide, DTPA(0)-; D007205:Indium Radioisotopes; D019275:Radiopharmaceuticals; D004369:Pentetic Acid; D001120:Arginine; D008239:Lysine; D015282:Octreotide; D004801:Eosine Yellowish-(YS); D006416:Hematoxylin