THE ABSORPTION OF HUMAN CALCITONIN FROM THE TRANSVERSE COLON OF MAN

Patients with a loop stoma were used to provide direct access to the t ransverse colon. The ease of delivery offers the chance to study absor ption of human calcitonin (hCT) in a defined region of the large intes tine difficult to access in healthy volunteers; i.v. infused hCT elici ted a standard pharmacokinetic profile in eight loop stoma patients sh owing a biphasic elimination with half-lives of 11.5 +/- 0.8 min and 3 3.7 +/- 1.8 min. hCT administration via the loop stoma was absorbed ac ross the transverse colonic mucosa in low amounts. The 10-mg dose achi eved a mean maximum plasma concentration of 1242 +/- 346 pg ml(-1), af ter 5-10 min with an absolute bioavailability of 0.22 +/- 0.06%. We co nclude that the transverse colon is a better site for the absorption o f human calcitonin than the more distal regions of the colon. This cou ld be a function of the transverse colonic epithelium. Alternatively, it could be due to the reduced levels of luminal debris and bacterial colonisation in the stoma patients compared with the previous studies carried out in the distal colon of healthy volunteers.