In vivo evaluation of a colonic delivery system using isotope techniques.
OBJECTIVE
To evaluate, using isotope techniques, the in vivo effectiveness of a pH-dependent colonic delivery system.


METHODS
In order to dispose of differently labelled substrates for measurement of orocaecal transit time, inulin-14C-carboxylic acid was evaluated as an alternative substrate to inulin and lactose-13C-ureide. Secondly, the time of release of 13C- and 15N-urea from the colonic delivery system was compared with the orocaecal transit time, measured using inulin and inulin-14C-carboxylic acid. This study was repeated after a 2-week lactulose intake period.


RESULTS
The orocaecal transit time determined using inulin-14C-carboxylic acid (398 min) was not significantly different from the orocaecal transit time determined using inulin (420 min) or lactose-13C-ureide (396 min). Before lactulose intake, the 13CO2 excretion time was 358 min and the orocaecal transit times determined with the inulin-14C-carboxylic acid and inulin breath test were 376 and 375 min respectively. After lactulose, the 13CO2 excretion time was 383 min and orocaecal transit times were 354 min for inulin-14C-carboxylic acid and 392 min for inulin. A highly significant correlation was found. Good agreement was found between the urinary 15N excretion and the appearance of 13CO2 in breath.


CONCLUSIONS
Isotope techniques provide an excellent non-invasive tool for the in vivo evaluation of a colonic delivery system.
Verbeke
K
K
Department of Gastrointestinal Research, University Hospital Gasthuisberg, Leuven, Belgium. Kristin.Verbeke@uz.kuleuven.ac.be
de Preter
V
V
Geboes
K
K
Daems
T
T
van den Mooter
G
G
Evenepoel
P
P
Rutgeerts
P
P
D000328:Adult; D001944:Breath Tests / Q000379:methods; D002214:Capsules; D002245:Carbon Dioxide / Q000378:metabolism; D002250:Carbon Radioisotopes; D002264:Carboxylic Acids; D003106:Colon / Q000502:physiology*; D004338:Drug Combinations; D016503:Drug Delivery Systems / Q000592:standards*; D005260:Female; D005772:Gastrointestinal Transit / Q000502:physiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007444:Inulin; D008297:Male; D009590:Nitrogen Radioisotopes; D014508:Urea / Q000378:metabolism / Q000652:urine
D002214:Capsules; D002250:Carbon Radioisotopes; D002264:Carboxylic Acids; D004338:Drug Combinations; D009590:Nitrogen Radioisotopes; D002245:Carbon Dioxide; D014508:Urea; D007444:Inulin