CHAPTER 41
DRUGS FOR BOWEL DISORDERS AND OTHER
GASTROINTESTINAL CONDITIONS
LEARNING OUTCOME 1
Identify the major anatomic structures of the lower gastrointestinal tract.
Concepts
The small intestine is the location for most nutrient and drug absorption; peristalsis is controlled by the
autonomic nervous system. Peptic ulcer is the most common disorder. The large intestine is responsible for the
reabsorption of water and excretion of fecal matter.
Figure 41.1 The Gastrointestinal Tract
LEARNING OUTCOME 2
Explain the pathogenesis of constipation and diarrhea.
Concepts
1. Constipation is the infrequent passage of hard, small stools. It is a symptom of an underlying disorder and a
common condition caused by lack of exercise; insufficient dietary fiber; diminished fluid intake; slow
motility of waste material through the large intestine; and certain foods, medications, and diseases.
2. Diarrhea is the increase in the frequency and fluidity of bowel movements and occurs when the colon fails
to reabsorb enough water. A type of body defense, diarrhea eliminates toxins and pathogens and certain
medications and infections. Prolonged diarrhea can lead to fluid, electrolyte, and acid–base imbalance.
Monitor diarrhea frequency and appearance, as it may be related to pseudomembranous colitis.
LEARNING OUTCOME 3
Discuss conditions in which the pharmacotherapy of bowel disorders is indicated.
Concepts
1. Laxatives and cathartics are given to treat or prevent constipation and to prepare the bowel for surgery or
diagnostic procedures. They promote emptying of the large intestine in several different ways. Stimulants
and herbal agents stimulate peristalsis. Mineral oil lubricates the fecal mass. Bulk-forming agents, stool
softeners or surfactants, saline or osmotic laxatives add more bulk or water to the colon contents.
2. Treatment for diarrhea depends on the severity and etiology. Opioids are administered for severe diarrhea;
they are the most effective and work by slowing peristalsis. Over-the-counter medications are given for
simple diarrhea; this group includes loperamide, bismuth compounds, psyllium preparations, and probiotic
supplements.
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3. Inflammatory bowel disease (IBD) includes both ulcerative colitis (erosions in the large intestine) and
Crohn’s disease (ulceration in the distal part of the small intestine). Symptoms of inflammatory bowel
disease range from mild to acute abdominal cramping and diarrhea. There are periods of remissions and
exacerbations.
4. Treatment of inflammatory bowel disease includes 5-aminosalicylic acid (5-ASA) agents such as
sulfonamide sulfasalazine (Azulfidine), olsalazine (Dipentum), and mesalamine (Asacol). Glucocorticoids
such as prednisone, methylprednisolone, and hydrocortisone are also used to treat this disease. The
treatment may also include immunosuppressant drugs such as azathioprine (Imuran), methotrexate (MTX),
and ifliximab (Remicade), a monoclonal antibody.
5. Irritable bowel syndrome (IBS) is also known as spastic colon or mucous colitis; it is a common disorder of
the lower gastrointestinal tract. Symptoms include abdominal pain, cramping, bloating, gas, and
constipation, alternating with diarrhea. It is a functional bowel disorder with no presence of detectable
disease. Stress and dietary factors precipitate symptoms.
6. Treatment of irritable bowel syndrome is supportive and treats the symptoms. Medications used are bulk
laxatives such as psyllium; anticholinergic medications to reduce bowel spasm, such as dicyclomine
(Bentyl); Tegaserod, which is one of only a few drugs approved for irritable bowel syndrome with
constipation; and serotonin agonists, which stimulate peristaltic reflex.
LEARNING OUTCOME 4
Explain conditions in which the pharmacotherapy of nausea and vomiting is indicated.
Concepts
1. Vomiting is a defense mechanism used by the body to rid itself of toxic substances. It is controlled by the
“vomiting center” located in the medulla of the brain. Vomiting is associated with many conditions,
including infection, poisoning, psychological factors, pain, and changes in body position. Many drugs can
cause nausea and vomiting as side effects, and this is a common reason to discontinue a drug. Emetogenic
potential is the capacity of a drug to induce vomiting.
2. Nausea and vomiting are treated with antiemetics. Simple nausea is treated with over-the-counter drugs and
herbal options. Serious nausea is treated with prescription drugs from many different classes, including
phenothiazines, antihistamines, anticholinergics, cannabinoids, glucocorticoids, benzodiazepines, and
serotonin receptor antagonists.
LEARNING OUTCOME 5
Describe the types of drugs used in the short-term management of obesity.
Concepts for Lecture
Anorexiants are drugs that affect hunger and/or appetite and are used for the short-term management of obesity.
These drugs produce only modest effects. In the 1970s amphetamine and dextroamphetamine were widely used;
however, they are addictive and now are rarely prescribed. Fen-phen in the 1990s and ephedra products in 2004
were taken off the market after causing heart problems. There are two anorexiants used today: orlistat, which
blocks lipid absorption in the gastrointestinal tract, and sibutramine, which is a selective serotonin reuptake
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inhibitor (SSRI).
LEARNING OUTCOME 6
Explain the use of pancreatic enzyme replacement in the pharmacotherapy of pancreatitis.
Concepts
Pancreatitis results when pancreatic enzymes (amylase and lipase) are trapped in the pancreas and not released
into the duodenum. It is associated with gallstones in women and alcoholism in men. Pharmacotherapy includes
replacement enzymes and supportive drugs for reduction of pain and gastric-acid secretion.
LEARNING OUTCOME 7
Describe the nurse’s role in the pharmacologic management of bowel disorders, nausea and vomiting, and other
GI conditions.
Concepts
1. The role of the nurse in the pharmacologic management of bowel disorders, nausea and vomiting, and other
GI conditions involves careful monitoring of a client’s condition and providing education as it relates to the
prescribed drug treatment. Obtain baseline medical, surgical, and drug history; lifestyle and dietary habits,
including use of herbal or alternative therapies; and a detailed description of symptomology and current
therapies.
2. Laxative therapy for bowel evacuation: Assess the abdomen for distension, bowel sounds, and bowel
patterns. If there is absence of bowel sounds, peristalsis must be restored prior to laxative therapy. Assess
for colon cancer, esophageal obstruction, intestinal obstruction, fecal impaction, and undiagnosed
abdominal pain. If diarrhea occurs, discontinue laxative use. Use with caution during pregnancy and
lactation. Take with one to two glasses of water. Assess the client’s ability to swallow. Assess for the
development of diarrhea and cramping. Assess for and educate clients about the proper use of laxatives and
stool softeners.
3. Antidiarrheal therapy: Assess hydration status, serum potassium, magnesium, and bicarbonate. Also assess
for blood in the stool. Antidiarrheals should not be used if constipation should be avoided, such as in
pseudomembranous colitis or severe ulcerative colitis. Assess the client’s ability to get out of bed safely.
Antidiarrheals are contraindicated in clients with severe dehydration, electrolyte imbalance, liver and renal
disorders, and glaucoma.
4. Tegaserod (Zelnorm) therapy for IBD: Prior to and during therapy, monitor liver and renal function.
Monitor cardiovascular status, especially in clients with preexisting cardiovascular disease. Tegaserod is
contraindicated in severe hepatic or renal impairment, bowel obstruction, gallbladder disease, and
abdominal pain. Administer the drug just prior to a meal with a full glass of water. Tablets may be crushed.
Do not give the drug to clients with frequent diarrhea because tegaserod accelerates gastric emptying.
5. Antiemetic therapy: Assess symptoms that precipitated the vomiting or that are occurring concurrently. If
a client becomes sedated and continues to vomit, a nasogastric tube with suction may be indicated. Client
safety is a concern because drowsiness is a frequent side effect. Clients may be at risk for falls because of
medication side effects and the sensation of weakness from vomiting. Immediately report vomiting of blood,
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or if the vomiting is associated with severe abdominal pain. Do not use OTC antiemetics for prolonged
periods; vomiting may be a symptom of a serious disorder that requires medical attention.
6. Drugs used to stimulate emesis should only be used in emergency situations under the direction of a health
care provider. They are used only when the client is alert because of the risk of aspiration. When the client is
comatose, a gastric lavage tube is placed and attached to suction to empty gastric contents. Before inducing
vomiting with an OTC emetic, check with the health care provider; some poisons and caustic chemicals
should not be vomited.
7. Anorexiant therapy: When administering anorexiants, focus on lifestyle changes that will have a greater
effect on weight reduction in the long term. Drugs for weight loss have limited effectiveness and potentially
serious side effects. Education of clients is essential; clients should not take OTC medications or herbal
medications without notifying their health care provider. If taking orlistat, the client should also take a
multivitamin each day but omit a dose if there is no fat present in the meal or if the meal is skipped. Client
should know that excessive flatus and fecal leaking may occur when a high-fat meal is consumed.
8. Pancreatic-enzyme replacement therapy: Assess dietary habits for use of foods that stimulate gastric and
pancreatic secretions. Assess for and monitor the presence, amount, and type of pain. Assess the symmetry
of the chest wall and the movement of the chest and diaphragm. Monitor for other abnormal findings, such
as elevated serum and urinary amylase and elevated serum bilirubin. Also monitor the client’s nutritional
and hydration status and for signs of infection. Check for pork allergy.
LEARNING OUTCOME 8
For each of the drug classes listed in Drugs at a Glance, know representative drugs, and explain the mechanism
of drug action, describe primary actions, and identify important adverse effects.
Concepts
1. Laxatives: Prototype drug: psyllium mucilloid (Metamucil). Mechanism of action: swells and increases the
size of the fecal mass. Primary use: to promote the passage of stool. The larger the size of the fecal mass, the
more the defecation reflex will be stimulated. Adverse effects: rarely produces side effects. It causes less
cramping than stimulant-type laxatives and results in a more natural bowel movement. If taken with
insufficient water, it may cause obstructions in the esophagus or intestine.
2. Antidiarrheals, Opioids: Prototype drug: diphenoxylate with atropine (Lomotil). Mechanism of action:
slows peristalsis, allowing time for additional water reabsorption from the colon and more solid stools.
Primary use: for moderate to severe diarrhea. Adverse effects: dizziness and drowsiness.
3. Drugs for Inflammatory Bowel Disease and Irritable Bowel Syndrome: Prototype drug: tegaserod
(Zelnorm). Mechanism of action: as a serotonin receptor agonist that causes an increase in stool formation
and the number of bowel movements. Primary use: for clients who have the constipation-dominant form of
irritable bowel syndrome. Adverse effects: There are no serious adverse effects. The most common side
effect is diarrhea, which usually occurs as a single episode and resolves as therapy progresses.
4. Antiemetics, Phenothiazines, and Phenothiazide-like Drugs: Prototype drug: prochloperazine
(Compazine). Mechanism of action: blocks dopamine receptors in the brain, which inhibits signals to the
vomiting center in the medulla. Primary use: for severe nausea and vomiting. Adverse effects: Dose-related
anticholinergic side effects such as dry mouth, sedation, constipation, orthostatic hypotension, and
tachycardia may occur. When used for prolonged periods at higher doses, extrapyramidal symptoms are a
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serious concern.
5. Anorexiants: Prototype drug: sibutramine (Meridia). Mechanism of action: as a selective serotonin
reuptake inhibitor (SSRI). Primary use: most widely prescribed appetite suppressant for the short-term
control of obesity. Adverse effects: Headache is the most common complaint reported during sibutramine
therapy, although insomnia and dry mouth also occur. It should be used with great care in clients with
cardiac disorders, as it may cause tachycardia and raise blood pressure.
6. Pancreatic-Enzyme Replacement: Prototype drug: pancrelipase (Lipancreatin, Pamcrease, Zymase).
Mechanism of action: contains lipase, protease, and amylase of pork origin, which facilitates the breakdown
and conversion of lipids into glycerol and fatty acids, starches into dextrin and sugars, and proteins into
peptides. Primary use: as replacement therapy for clients with insufficient pancreatic exocrine secretions.
Adverse effects: gastrointestinal symptoms of nausea, vomiting, and/or diarrhea; can cause metabolic
symptom of hyperuricosuria.
Prototype Drug

psyllium mucilloid (Metamucil)

diphenoxylate with atropine (Lomotil)

tegaserod (Zelnorm)

prochloperazine (Compazine)

sibutramine (Meridia)

pancrelipase (Lipancreatin, Pamcrease, Zymase)
ANIMATIONS AND VIDEOS

Mechanism of Action: Tegaserod (Zelnorm)
LEARNING OUTCOME 9
Use the nursing process to care for patients who are receiving drug therapy for bowel disorders, nausea and
vomiting, and other GI conditions.
Concepts
1. Laxatives are drugs that promote bowel movements. Many are available over the counter for the selftreatment of simple constipation. (Doses of laxatives are identified in Table 41.1.) There are several types of
laxative: Bulk-forming agents absorb water, thus adding size to the fecal mass. Stool softeners or surfactants
cause more water and fat to be absorbed into the stools. Stimulants irritate the bowel to increase peristalsis.
Saline or osmotic laxatives are not absorbed in the intestine; they pull water into the fecal mass to create a
more watery stool. Herbal agents are natural products available OTC that are widely used for self-treatment
of constipation. The most commonly used herbal laxative is senna, a potent herb that irritates the bowel and
increases peristalsis. Miscellaneous agents include mineral oil, which acts by lubricating the stool and the
colon mucosa.
2. For mild diarrhea, OTC products are effective at returning elimination patterns to normal. For chronic or
severe cases, the opioids are the most efficacious of the antidiarrheal agents. (The antidiarrheals are shown
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in Table 41.2.)
3. Drugs for inflammatory bowel disease and irritable bowel syndrome are from several classifications. Mildto-moderate IBD is treated with 5-aminosalicylic acid (5-ASA) agents. Corticosteroids are used in more
persistent cases. Particularly severe disease may require immunosuppressant drugs. Treatment of IBS is
supportive, with drug therapy targeted at symptomatic treatment, depending on whether constipation or
diarrhea is the predominant symptom. Medications include bulk laxatives, anticholinergic drugs, and
serotonin agonists.
4. Antiemetic drugs from at least eight different classes are used to prevent nausea and vomiting. Many of
these act by inhibiting dopamine or serotonin receptors in the brain. (The antiemetics are shown in Table
41.3.)
5. Anorexiants are drugs used to induce weight loss by suppressing appetite and hunger. Despite the public’s
desire for effective drugs to promote weight loss, however, there are few such drugs on the market. The
approved agents produce only modest effects.
6. The pancreas secretes essential digestive enzymes. The enzymatic portion of pancreatic juice contains
carboxypeptidase, chymotrypsin, and trypsin, which are converted to their active forms once they reach the
small intestine. Three other pancreatic enzymes—lipase, amylase, and nuclease—are secreted in their active
form but require the presence of bile for optimum activity. Because lack of secretion will result in
malabsorption disorders, replacement therapy is sometimes warranted.
Table 41.1 Laxatives and Cathartics
Table 41.2 Antidiarrheals
Table 41.3 Selected Antiemetics
LEARNING OUTCOME 10
Use the nursing process to care for clients who are receiving drug therapy for bowel disorders, nausea and
vomiting, and other GI conditions.
Concepts
1. Assessment: Prior to administration, obtain a complete health history, including allergies, drug history, and
possible drug interactions. Assess sodium, chloride, and potassium levels. Evaluate results of stool culture.
Assess for presence of dehydration. Obtain vital signs and ECG.
2. Nursing Diagnoses: Risk for Imbalanced Fluid Volume: Less Than Body Requirements related to fluid loss
secondary to diarrhea; Risk for Injury (Falls) related to drowsiness secondary to drug therapy.
3. Planning: The client will report relief of diarrhea; demonstrate an understanding of the drug’s action by
accurately describing drug side effects and precautions; immediately report effects such as persistent
diarrhea, constipation, abdominal pain, blood in stool, confusion, dizziness, or fever.
4. Implementation: Monitor frequency, volume, and consistency of stools. Minimize the risk of dehydration
and electrolyte imbalance. Prevent accidental overdosage. Monitor for dry mouth. Initiate safety measures to
prevent falls. Monitor electrolyte levels.
5. Evaluation: The client reports relief of diarrhea. The client accurately states the drug’s action and side
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effects. The client accurately states signs and symptoms to be reported to the health care provider.
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