INDIRECT GASTROINTESTINAL TRANSIT MONITORING AND ABSORPTION OF THEOPHYLLINE

The gastrointestinal transit and absorption of a multiparticulate cont rolled-release theophylline preparation were investigated under fed an d fasted conditions. Transit of the theophylline pellets in the gastro intestinal tract was monitored using two marker drugs, namely, paracet amol and sulfasalazine. Food was found to delay the gastric emptying a nd caecal arrival of the pellets, but had no significant effect on the small intestinal transit time. The delay in gastric emptying was asso ciated with a delay in drug absorption. Under the fasted condition, ap proximately 13% of the drug was absorbed while the pellets were in the stomach, 57% while in the small intestine and the remaining amount wh ile in the colon. As for the fed mode, the percent absorbed while the pellets were in these regions were 9%, 72%, and 19%, respectively.