Download Drug treatment for irritable bowel syndrome

ask if patients with gas and bloating are drinking too
much carbonated beverages, drinking with a straw or
chewing gum, all of which can lead to aerophagia,
advise against excessive intake of fats, which can lead to
gas retention,
advise against eating certain carbohydrates, such as
beans, cabbage, broccoli and cauliflower, which may lead
to fermentation and gas in the colon, and
encourage patients with constipation to increase fiber
intake. Studies suggest this can help relieve constipation
but not relieve pain.
Drug therapy
Consider drug therapy to reduce pain and diarrhea or consti-
pation even though the effectiveness of most pharmacologic
agents may be limited. In a study of 350 patients with IBS,
more than half (55%) taking prescription drugs for IBS felt
that they were ineffective or only somewhat effective. More
than 60% reported adverse effects, and 40% taking over-thecounter medications reported they were ineffective.
The FDA has only approved two drugs, tegaserod maleate
and alosetron hydrochloride, both of which now have restricted use. Tegaserod, a 5-HT4-receptor agonist, was approved
for treatment of constipation-predominant IBS but is restricted because of an association with myocardial infarction and
stroke. Alosetron, a 5-HT3-receptor antagonist, was approved
for diarrhea-predominant IBS but has been restricted
because of a 1 in 700 risk of ischemic colitis. Prescribing
Drug treatment for irritable bowel syndrome
physicians must register with the manufacturer and patients
must sign a consent form to begin therapy.
Other drugs may provide relief for some patients with IBS.
These include antispasmodics, laxatives, antidiarrheals, antidepressants and antibiotics. (See table, “Drug treatment for
irritable bowel syndrome.”)
Consider antispasmodics as a first-line agent for pain since
they reduce contractions in the colon. The two available in
the U.S. are dicyclomine and hyoscyamine. They should be
taken before meals if postprandial urgency, diarrhea and
cramping are problems.
Saline-type laxatives may help patients with constipation
that is not responsive to increased fiber intake. One study
showed that daily administration of low-dose polyethylene
glycol laxatives increases bowel frequency and decreases
symptoms in chronic constipation. Expert consensus suggests that osmotic laxatives such as magnesium citrate or
sodium phosphate are safe and effective for severe constipation when used daily or as needed. Regular use of stimulant
cathartics such as senna, cascara and phenolphthalein
should be avoided because they can cause cramps.
Agent
Mechanism of action
Dosage
Benefits
Antispasmodics
Reduce contractions in colon and
small bowel which may produce diarrhea and cramps
Generally given prn, especially
before meals
Reduce pain
Dicyclomine
Reduce contractions in colon and
small bowel which may produce diarrhea and cramps
10-20 mg po before meals
Reduce pain
Hyoscyamine
Reduce contractions in colon and
small bowel which may produce diarrhea and cramps
1.25 mg po before meals prn or
0.125 sl 3.75 mg xl po bid
Reduce pain
Combination
antispasmodic/
sedative
Additive effect of sedative to reduce
GI motility
1-2 po q6h prn
Useful for pain, especially if patient
anxious and antispasmodics alone
have failed
Clidinium bromide/
chlordiazepoxide (Librax)
Additive effect of sedative to reduce
GI motility
Before meals or q6h prn
Useful for pain, especially if patient
anxious and antispasmodics alone
have failed
Phenobarbital,
hyoscyamine, atropine,
scopolamine (Donnatal)
Additive effect of sedative to reduce
GI motility
Useful for pain, especially if patient
Same phenobarbital, 16 mg;
anxious and antispasmodics alone
hyoscyamine, 0.1 mg; atropine,
0.02 mg; scopolamine, 0.006 mg have failed
Laxatives
Colon lavage
prn or scheduled
Reduces distention of colon due to
retained stool
Saline cathartics:
Polyethylene glycolelectrolyte solution
(Miralax), GoLytely
Magnesium based, phosphate based,
PEG
Titrate to effect
Reduces distention of colon due to
retained stool. PEG-based lavage
solutions useful for severe constipation taken a few glasses qhs
Osmotic cathartics:
Sorbitol
Sorbitol 30%, lactulose
Titrate to effect
Reduces distention of colon due to
retained stool. PEG-based lavage
solutions useful for severe constipation taken a few glasses qhs
Anti-diarrheals
Mu opiate agonists have primarily gut Titrate to effect
effect to increase segmenting contractions and decrease propulsive ones
Reduces diarrhea
Loperamide
Mu opiate agonist phenylpiperidine
1-2 po q6h prn diarrhea, titrate
to effect
Has been shown to reduce diarrhea
but not pain
FOLLOW-UP
Diphenoxylate/Atropine
Mu opiate agonist with anticholinergic
1-2 po q6h prn diarrhea, titrate
to effect. Diphenoxylate, 2.5
mg; atropine, 0.025 mg
Reduces diarrhea
Cholestyramine
Bile acid binder and nonspecific constipating agent
4 g po qd to bid to start,
titrate to effect
Reduces diarrhea
Serotonin-3 antagonists:
Alosetron
Reduces intestinal pain sensitivity in
animals. Helps diarrhea-predominant
IBS in women. Reduces gut transit and
increases colon compliance
1 mg po bid
Reduces pain and diarrhea. Appears
to be effective only in women.
Improves quality of life
Reassess patients with IBS over time to ensure that a more
serious disorder is not being overlooked. Determine that
symptoms are not progressive and that red flag symptoms
have not developed. Reassure the patient that there are no
long-term complications or risk of cancer associated with IBS
even though IBS symptoms are typically chronic and fluctuating in severity. Carefully consider the need for diagnostic
tests or referral if symptoms are refractory and persistent.
Serotonin-4 antagonists:
Tegaserod
Stimulates peristalsis and accelerates
gut transit mouth to cecum via 5HT-4
receptor in enteric nervous system
6 mg po bid
Relief of constipation-predominant
IBS symptoms, especially constipation and pain to a lesser degree.
Antibiotics:
Neomycin
IBS symptoms may be related to
intestinal bacterial overgrowth
500 mg bid x 10 days
200 mg, 2 tabs tid for 10 days
Rifaximin
Tricyclic anti-depressants
Reduce pain and diarrhea, mechanism
unknown. Not mediated by depression
treatment
Doses needed are lower than
depression doses
Amitriptyline
10-100 mg qhs
Desipramine
10-100 mg qhs
Trazodone
10-100 mg qhs
IBS symptoms may be related to intestinal bacterial overgrowth. Several double-blind studies have shown that the
antibiotics rifaximin and neomycin improve IBS symptoms.
However, neomycin only works in 25% of patients and has
side effects that limit its use, making rifaximin the preferred
choice.
In addition, IBS patients with preexisting psychiatric problems such as depression may benefit from tricyclic antidepressants. Best results are obtained with a low starting dose,
then gradual increases as tolerated. Using selective serotonin
reuptake inhibitors may increase the quality of life for patients
with severe IBS and associated psychological distress.
PATIENT EDUCATION
Patient education can help patients with IBS. Explain the connection between IBS and previous gastrointestinal infection
and bacterial overgrowth. Explain that IBS generally is a
chronic condition and that patients can help themselves by
taking medication as needed, eliminating diet triggers and
understanding psychological triggers.
This information comes from the PIER module
“Irritable Bowel Syndrome” (http://pier.acponline.org).
The information included herein should never be used as a
substitute for clinical judgment and does not represent an
official position of ACP.
10-100 mg qhs
Doxepin
SSRIs
Reduced pain, especially in diarrheapredominant IBS
Loperamide is a first-line agent for diarrhea symptoms. It can
be taken as needed or on a scheduled basis depending on
severity and frequency. Other opioid antidiarrheal agents,
such as diphenoxylate hydrochloride combined with atropine
sulfate, also may be effective.
Unknown; may increase gut compliance or have psychological action
Depression doses and lower
doses have been used
May reduce pain. Effective for
depression if present
See PIER for side effects and other notes
bid = twice daily; CNS = central nervous system; GI = gastrointestinal; IBS = irritable bowel syndrome; po = oral; qd = once daily;
qhs = every night; sl = sublingual.
9