The absorption of human calcitonin from the transverse colon of man

Patients with a loop stoma were used to provide direct access to the transverse colon. The ease of delivery offers the chance to study absorption of human calcitonin (hCT) in a defined region of the large intestine difficult to access in healthy volunteers; i.v. infused hCT elicited a standard pharmacokinetic profile in eight loop stoma patients showing a biphasic elimination with half-lives of 11.5 +/- 0.8 min and 33.7 +/- 1.8 min. hCT administration via the loop stoma was absorbed across the transverse colonic mucosa in low amounts. The 10-mg dose achieved a mean maximum plasma concentration of 1242 +/- 346 pg ml(-1), after 5-10 min with an absolute bioavailability of 0.22 +/- 0.06%. We conclude that the transverse colon is a better site for the absorption of human calcitonin than the more distal regions of the colon. This could 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.