Although uncommon, medication-induced colonotoxicity is important to recognize because medication cessation generally leads to prompt clinical improvement, while medication continuation results in
disease exacerbation. This review categorizes the association between medications and colonotoxicity as "well-established" or "probable," according to the following criteria: total number of reported cases, number of different research groups reporting an association, experimental and pharmacologic evidence of an association, and validity of an association in each reported case.
Cocaine,
ergotamine,
estrogen,
sodium polystyrene,
alosetron,
amphetamines,
pseudoephedrine, and
vasopressin are associated with colonic
ischemia. The mechanisms include vasospasm, thrombogenesis, and shunting of blood from mesenteric vessels.
Narcotics,
phenothiazines,
vincristine,
atropine,
nifedipine, and
tricyclic antidepressants are associated with
colonic pseudo-obstruction. The mechanisms include antagonizing prokinetic
neurotransmitters, stimulating antikinetic
neurotransmitters, promoting dysmotility, relaxing smooth muscle, and injuring enteric neurons. Numerous
antibiotics are associated with
pseudomembranous colitis;
ampicillin is associated with hemorrhagic
colitis;
chemotherapy is associated with neutropenic
colitis; and
deferoxamine is associated with Yersinia
enterocolitis. Mechanisms of these toxicities include altering normal bowel flora, weakening immunologic defenses, promoting microorganism virulence, and mucosal injury.
Gold compounds, nonsteroidal antiinflammatory drugs,
alpha-methyldopa,
salicylates, and
sulfasalazine are associated with an inflammatory or cytotoxic
colitis. The mechanisms include direct mucosal cytotoxicity,
antimetabolite effects, or
drug allergy. Nonsteroidal antiinflammatory drugs,
cyclo 3 fort,
flutamide,
lansoprazole, and
ticlopidine are associated with
lymphocytic colitis. The mechanisms include immunologic activation or attenuated immunologic defenses. Chronic
cathartic use leads to colonic hypomotility and abdominal distention. Intrarectally administered
corrosive compounds can produce a toxic
colitis.