Additional drugs in classes
of their own are also used in the treatment and/or prevention of various GI
condi-tions. They include misoprostol, sucralfate, and oc-treotide.
Prostaglandins of the A, E,
and I type inhibit gastric acid secretion. The prostaglandins also stimulate
in-creased mucus and bicarbonate secretion by gastric mu-cosa. Misoprostol (Cytotec), which is an analogue of
prostaglandin E1, has been approved for use in the pre-vention of
nonsteroidal antiinflammatory drug–induced ulceration. It also is approved in
other countries for the treatment of peptic ulcer disease. Misoprostol is
ab-sorbed rapidly after oral administration and is hy-drolyzed to the active
compound. It is metabolized by the liver and excreted mainly in the urine.
Adverse ef-fects include crampy abdominal pain, dose-related diar-rhea, and
uterine contractions. The last-named effect has led to its use in the control
of postpartum bleeding .
Sucralfate (Carafate) is an aluminum
hydroxide–sul-fated sucrose complex that is only minimally absorbed from the GI
tract. After exposure to gastric acid, the compound becomes negatively charged,
creating a vis-cous adherent complex. This complex is believed to in-hibit
back-diffusion of H+ . Other effects are a direct re-duction in
pepsin activity and a slight rise in tissue prostaglandin levels. Stimulation
of a cytoprotection mechanism may therefore assist mucosal healing. The drug
has no acid-buffering capacity.
Sucralfate is frequently used
for prophylaxis of stress-induced gastritis in patients in intensive care
units. It has also been successfully used in small num-bers of patients as a
suspension enema to treat radiation proctitis.
Constipation is the main side
effect associated with its oral use. As with other aluminum compounds, the drug
may bind phosphorus, resulting in secondary hy-pophosphatemia. Binding to a
number of other coad-ministered medications may result in a significant
re-duction in their bioavailability.
Octreotide (Sandostatin) is a synthetic somatostatin
analogue. It is used in a variety of situations and must be given
subcutaneously or intravenously. Most commonly, it is used as a continuous
intravenous infusion in pa-tients hospitalized with bleeding varices, because
A long-acting depot form is
approved for the suppression of severe diarrhea and flushing as-sociated with
malignant carcinoid syndrome and for the treatment of the profuse watery
diarrhea associated with vasoactive intestinal peptide tumor.