title: Radiopharmacokinetics of radioiodine in the parotid glands after the administration of lemon juice.
abstract: BACKGROUND
  The ability of sialagogues to increase or decrease radiation induced-sialoadenitis and/or xerostomia after therapeutic administration of ¹³¹I is controversial. To evaluate this we measured the radiopharmacokinetics of ¹²³I in the parotid glands (PGs) after its administration of lemon juice (LJ).
  
  
  METHODS
  A retrospective review was performed on all patients who had a salivary gland scan performed before ¹³¹I therapy between July 2008 and April 2009 at the Washington Hospital Center. Two hours after ¹²³I was given orally, dynamic scintigraphy was initiated. Five milliliters of LJ was given 5 minutes later. Then, the patient was imaged for 1 hour (phase 1) at which point the sequence was repeated (phase 2). Twenty-three patients were studied. For each PG, the presence or absence of uptake was assessed, and based on background corrected counts, the mean, range, and standard deviation were determined for multiple radiopharmacokinetic parameters such as (i) percent radioiodine washout, (ii) time from LJ administration to re-accumulation of radioiodine to pre-LJ activity, and (iii) percent reduction in radiation absorbed dose to the PGs if LJ had been re-administered at the time the radioiodine activity re-accumulated to the pre-LJ activity.
  
  
  RESULTS
  The mean  ± one standard deviation and range for percent washout were 84%  ± 18% (35%-100%) and 83%  ±  21% (37%-100%) in phase 1 and 2, respectively. The times from LJ to re-accumulation of the radioiodine to the pre-LJ activity were 21  ± 10 minutes (4-45 minutes) and 40  ± 14 minutes (12-62 minutes) for phase 1 and 2, respectively. The estimated percent reduction in radiation absorbed dose to the PGs following the first and second administration of LJ was 37%  ± 14% (13%-93%) and 47% ± 16% (21%-97%), respectively.
  
  
  CONCLUSIONS
  The washout of radioiodine from the PGs is rapid but transient. Early repeat administration may result in continued and cumulative reduction of radiation absorbed dose in the PGs.
authors.affiliation: Division of Nuclear Medicine, Washington Hospital Center,110 Irving Street NW, Washington, DC 2001, USA. douglas.van.nostrand@medstar.net
authors.forename: Douglas
authors.initials: D
authors.lastname: Van Nostrand
authors.forename: Varalakshmi
authors.initials: V
authors.lastname: Bandaru
authors.forename: Shyam
authors.initials: S
authors.lastname: Chennupati
authors.forename: Jason
authors.initials: J
authors.lastname: Wexler
authors.forename: Kanchan
authors.initials: K
authors.lastname: Kulkarni
authors.forename: Frank
authors.initials: F
authors.lastname: Atkins
authors.forename: Mihriye
authors.initials: M
authors.lastname: Mete
authors.forename: Gurudev
authors.initials: G
authors.lastname: Gadwale
mesh_terms: D000328:Adult; D000368:Aged; D001628:Beverages; D002957:Citrus; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D010306:Parotid Gland / Q000187:drug effects / Q000378:metabolism*; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012793:Sialadenitis / Q000188:drug therapy; D013964:Thyroid Neoplasms / Q000175:diagnosis*
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals