title: Use of the InteliSite capsule to study ranitidine absorption from various sites within the human intestinal tract.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the extent of ranitidine absorption from an externally activated drug-delivery system in two distinct regions of the intestine (jejunum and ileum) in healthy human volunteers. This investigation also was designed to evaluate the utility of the InteliSite capsule for studying regional intestinal drug absorption in humans.
  
  
  METHODS
  The intestinal absorption of ranitidine from the jejunum and ileum was compared in eight, healthy volunteers in this open-label, two-way crossover study. In two of the eight volunteers, absorption from the colon also was studied. Subjects swallowed the capsule containing ranitidine solution (121 mg) and 100 microCi of 99mTc-DTPA. The endcap of the capsule contained 20 microCi of (111)In-DTPA. At the desired intestinal site, the capsule was activated by the application of an external RF magnetic signal (6.78 MHz operating frequency) and the ranitidine solution was released. Blood samples were collected from a forearm vein for 12 hours after capsule activation.
  
  
  RESULTS
  The capsule released the ranitidine solution when activated in the jejunum, ileum and colon (visualized by the gamma camera). There was no difference in the extent of ranitidine absorption or ranitidine pharmacokinetics when the capsule was activated in the jejunum or ileum.
  
  
  CONCLUSIONS
  This study demonstrates the utility of a novel, externally activated drug-delivery system to assess site-specific intestinal drug absorption in humans. Results indicate that use of the InteliSite capsule method to evaluate site-specific intestinal ranitidine absorption in humans yields data similar to that obtained previously by means of oral intubation studies.
authors.affiliation: Division of Pharmaceutics, School of Pharmacy, University of North Carolina, Chapel Hill 27599, USA.
authors.forename: Y K
authors.initials: YK
authors.lastname: Pithavala
authors.forename: W D
authors.initials: WD
authors.lastname: Heizer
authors.forename: A F
authors.initials: AF
authors.lastname: Parr
authors.forename: R L
authors.initials: RL
authors.lastname: O'Connor-Semmes
authors.forename: K L
authors.initials: KL
authors.lastname: Brouwer
mesh_terms: D000328:Adult; D000897:Anti-Ulcer Agents / Q000493:pharmacokinetics*; D003106:Colon / Q000378:metabolism; D018592:Cross-Over Studies; D004339:Drug Compounding; D016503:Drug Delivery Systems; D015902:Gamma Cameras; D006801:Humans; D007082:Ileum / Q000378:metabolism; D007408:Intestinal Absorption; D007583:Jejunum / Q000378:metabolism; D011899:Ranitidine / Q000493:pharmacokinetics*; D016284:Technetium Tc 99m Pentetate
chemical_list: D000897:Anti-Ulcer Agents; D011899:Ranitidine; D016284:Technetium Tc 99m Pentetate