Drug Targeting Organ-Specific Strategies

log viable count / g content
11
10
9
8
7
6
5
4
3
2
oral cavity
stomach
duodenum
jejunum
sit time can last for up to 78 h, thereby allowing the absorption of drugs of even low permeability
such as peptides.
6.3 Pathological Processes in the Colon
ileum
cecum
rectum
6.3 Pathological Processes in the Colon 159
Bacteroides
Eubacteria
Anaerobic streptococci
Bifidobacteria
Enterococci
Coliform bacteria
Lactobacilli
Veillonellae
Clostridium perfringens
Figure 6.1. Bacterial flora of the human GI tract. Modified from reference [4].
Ulcerative or inflammatory lesions may affect the physiology of the small and large intestine.
Ulcer formation entails a circumscribed loss of tissue from the surface of an organ, which results
from necrosis following cell destruction by chemicals and the like, or by restriction of
the blood supply. Ulcers are among the most common and important lesions. Those that do
not penetrate the muscularis mucosa are called erosions. Ulcerative conditions in humans
must be differentiated from malignant ulcers, which are associated with neoplasia. Among
pH
10
9
8
7
6
5
4
3
2
1
proximal small intestine
small intestine large intestine
mid small intestine
distal small intestine
right
colon
mid
colon
left
colon
0
0 2 4 6 8 10 12 14 16 18 20
time after ingestion of a radiotelemetry capsule [h]
Figure 6.2. pH profile in the GI tract of a healthy subject, measured with a radiotelemetry capsule.
Modified from reference [5].