title: Measurement of drug concentration in the stomach after intragastric administration of drug solution to healthy volunteers: analysis of intragastric fluid dynamics and drug absorption.
abstract: OBJECTIVE
  To evaluate the time-profile of intragastric fluid volume in humans after intragastric administration of drug solution.
  
  
  METHODS
  Eight healthy volunteers were intragastrically administered 150 mL of drug solution containing atenolol (non-absorbable marker) and salicylic acid, then, aliquots of gastric fluid (ca. 2 mL) were sampled for 2 h through the catheter. Rate constants for secretion and emptying of the fluid were obtained by fitting the time-course of atenolol concentration to the simple gastric fluid transit model. Absorption of salicylic acid from the stomach was estimated by comparing its gastric concentration with that of atenolol.
  
  
  RESULTS
  Kinetic analysis of atenolol concentration in the stomach indicated a rapid emptying of the fluid with an average half-life of 4.2 min. Steady-state intragastric fluid volume in 8 volunteers was estimated as 4-133 mL with an average of 42 mL. Intragastric concentration (normalized by dose) of salicylic acid was always lower than that of atenolol, showing approximately 40% of salicylic acid was absorbed from the stomach before emptying to the intestine.
  
  
  CONCLUSIONS
  This study provided valuable information on intragastric fluid dynamics and gastric drug absorption in humans to establish a better in vitro-in vivo correlation in oral drug absorption.
authors.affiliation: Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotobe-cho, Hirakata, Osaka, 573-0101, Japan. shinji@pharm.setsunan.ac.jp
authors.forename: Shinji
authors.initials: S
authors.lastname: Yamashita
authors.forename: Makoto
authors.initials: M
authors.lastname: Kataoka
authors.forename: Haruki
authors.initials: H
authors.lastname: Higashino
authors.forename: Shinji
authors.initials: S
authors.lastname: Sakuma
authors.forename: Takashi
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Hinako
authors.initials: H
authors.lastname: Uchimaru
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsukikawa
authors.forename: Masanari
authors.initials: M
authors.lastname: Shiramoto
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Uchiyama
authors.forename: Hidehisa
authors.initials: H
authors.lastname: Tachiki
authors.forename: Shin
authors.initials: S
authors.lastname: Irie
mesh_terms: D000328:Adult; D001262:Atenolol / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005746:Gastric Emptying; D006207:Half-Life; D006801:Humans; D057446:Hydrodynamics; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption; D007700:Kinetics; D008297:Male; D020156:Salicylic Acid / Q000008:administration & dosage / Q000493:pharmacokinetics*; D013270:Stomach / Q000502:physiology*; D055815:Young Adult
chemical_list: D001262:Atenolol; D020156:Salicylic Acid