Colon ascendens

In terms of size and complexity, the human colon falls between that of carnivores, such as the ferret which have no discemable jrmction between ileum and colon, and herbivores like the rat, which has a voluminous cecum. The cecum, colon ascendens, colon transversale, colon descendens, and rectosigmoid colon make up the colon. It... 

It must be taken into account that the intestinal microflora may change transiently because of illness, medication (e.g., antibiotics), or substantial changes in food intake. However, the microflora has an intrinsic mechanism of regulation that is able to restore normal standards within a relatively short time [37-39], As mentioned before, although the colonic absorption conditions are relatively good in the colon ascendens, they are, even under normal conditions, not as favorable as in the small intestine and become increasingly less favorable with increasing viscosity and consistency. 

In these studies, standard bioavailability variables such as the extent of bioavailability determined from area under the curve (AUC), rate of bioavailability related to peak plasma drug levels (Cmax) and time to peak (fmax) are determined. A more detailed presentation of the assumptions and interpretations of bioavailability data is given in Chapter 7. The bioavailability after administration in more distal parts of the intestine, such as the terminal ileum and different parts of the colon, is compared with a reference administration either as an oral solution or as a regional delivery to the upper small intestine. This is exemplified in Figure 4.18, which shows the plasma drug concentrations of metoprolol after administration to jejunum, terminal ileum and colon ascendens or transversum. 

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