Magnetic resonance imaging for the in vivo evaluation of gastric-retentive tablets.
OBJECTIVE
To develop a magnetic resonance imaging (MRI) technique for assessing in vivo properties of orally ingested gastric-retentive tablets under physiologic conditions.


METHODS
Tablets with different floating characteristics (tablet A-C) were marked with superparamagnetic Fe3O4 particles to analyze intragastric tablet position and residence time in human volunteers. Optimal Fe3O4 concentration was determined in vitro. Intragastric release characteristic of one slow-release tablet (tablet D) was analyzed by embedding gadolinium chelates (Gd-DOTA) as a drug model into the tablet. All volunteers underwent MRI in the sitting position. Tablet performance was analyzed in terms of relative position of tablet to intragastric meal level (with 100% at meal surface), intragastric residence time (min) and Gd-DOTA distribution volume (% of meal volume).


RESULTS
Intragastric tablet floating performance and residence time of tablets (tablet A-D) as well as the intragastric Gd-DOTA distribution of tablet D could be monitored using MRI. Tablet floating performance was different between the tablets (A, 93%(95 - 9%); B, 80%(80 - 68%): C, 38%(63 - 32%); p < 0.05). The intragastric distribution volume of Gd-DOTA was 19.9% proximally and 35.5% distally.


CONCLUSIONS
The use of MRI allows the assessment of galenic properties of orally ingested tablets in humans in seated position.
Steingoetter
Andreas
A
Biophysics Group, Institute of Biomedical Engineering, University and ETH Zurich Gloriastrasse, 35 CH-8092 Zurich, Switzerland. steingoetter@biomed.ee.ethz.ch
Weishaupt
Dominik
D
Kunz
Patrick
P
Mäder
Karsten
K
Lengsfeld
Hans
H
Thumshirn
Miriam
M
Boesiger
Peter
P
Fried
Michael
M
Schwizer
Werner
W
D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems; D005290:Ferric Compounds / Q000737:chemistry; D006571:Heterocyclic Compounds; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009942:Organometallic Compounds; D013270:Stomach / Q000033:anatomy & histology*; D013607:Tablets
D003692:Delayed-Action Preparations; D005290:Ferric Compounds; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; D013607:Tablets; C000499:ferric oxide; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate