Monitoring the intragastric distribution of a colloidal drug carrier modelby magnetic resonance imaging460

Purpose Monitoring the distribution of drugs or drug delivery systems in th e human gastrointestinal tract is an important prerequisite for the design of orally administered drugs. We investigated the intragastric distribution of a colloidal drug delivery system (liposomes containing the contrast age nt Gd-DOTA) by magnetic resonance imaging. Methods. Following ingestion of a liquid or a solid meal, gastric distribut ion of liposomes released from a capsule and the fat component of the solid meal were tracked in 7 healthy subjects for 90 min. Liposomes were identif ied in gastric content by the increased signal intensity provided by the en capsulated Gd-DOTA. Results, With the liquid meal, liposomes initially formed a layer on the su rface before distributing in 86 +/- 2% of gastric content (maximum distribu tion volume) within 42 +/- 6 min. With the solid meal, maximum distribution (7 +/- 1%, reached within 24 +/- 6 min) was confined to a small volume in the fundus without forming a layer, suggesting that distribution was relate d to tire accessible liquid compartment Fat distribution was inhomogeneous and: concentrated in the fundus. Conclusions. Intragastric distribution of a colloidal drug carrier model su ch as Gd-DOTA-filled liposomes, varies between meals of different compositi on. These differences can be monitored in three dimensions in humans by MRI .