Drugs for Gastrointestinal Disorders 29 Drugs for Gastrointestinal Disorders

Directory Classroom Response System Lecture Note Presentation

Question 1 After administering an antiemetic, the patient should be placed in what position?

Question 1 Choices Face up Side lying Upright Face down

Question 1 Answer Face up Side lying Upright Face down

Question 2 Which of the following substances should be avoided when the patient has a peptic ulcer?

Question 2 Choices Aspirin Raw foods Anorexiants Antiemetics

Question 2 Answer Aspirin Raw foods Anorexiants Antiemetics

Question 3 The patient with a gastric ulcer has been started on ranitidine (Zantac). Instructions should include:

Question 3 Choices Drug therapy will extend over several weeks or months. Information about the signs and symptoms of CNS depression. Drug therapy will extend over a few days. Information about the signs and symptoms of hepatic disease.

Question 3 Answer Drug therapy will extend over several weeks or months. Information about the signs and symptoms of CNS depression. Drug therapy will extend over a few days. Information about the signs and symptoms of hepatic disease.

Question 4 Your patient is taking nizatidine (Axid) and magaldrate (Riopan). The patient should:

Question 4 Choices Not take the medications at the same time Switch to another antacid that is safer with this drug Not be taking magaldrate because it is not effective

Question 4 Answer Not take the medications at the same time Switch to another antacid that is safer with this drug Not be taking magaldrate because it is not effective

Learning Outcomes Describe the major anatomical structures of the digestive system. Identify common causes, signs, and symptoms of peptic ulcer disease and gastroesophageal reflux disease. Identify the major classes of drugs used to treat peptic ulcer disease and GERD.

Learning Outcomes Explain why two or more antibiotics are used concurrently in the treatment of H. pylori. Explain conditions when the drug treatment of constipation is warranted. Identify the major classes of laxatives.

Learning Outcomes Explain conditions when the drug treatment of diarrhea is warranted. Identify the major classes of antiemetics. Describe the types of drugs used in the short-term management of obesity and their effectiveness.

Learning Outcomes Describe the pharmacotherapy of pancreatic insufficiency. For each of the following classes listed in the Drug Snapshot, identify representative drugs, and explain the mechanisms of drug action, primary actions related to the digestive system, and important adverse effects:

Learning Outcomes Categorize drugs used in the treatment of digestive system disorders based on their classifications and mechanisms of action.

Core Concept 29.1 The digestive system breaks down food, absorbs nutrients, and eliminates wastes.

Figure 29.1 The digestive system

Core Concept 29.2 Peptic ulcer disease is caused by an erosion of the mucosal layer of the stomach or duodenum.

Risk Factors Close family history of PUD Blood group O Smoking tobacco Alcoholic beverages Beverages and food containing caffeine

Risk Factors Drugs, including glucocorticoids, aspirin, and NSAIDs Excessive psychological stress Infection with the bacterium Helicobacter pylori

Figure 29.2 Natural defenses against stomach acid

Figure 29.3 Mechanism of peptic ulcer formation Reprinted by permission of Pearson Education, Inc., Upper Saddle River, NJ

Duodenal Ulcer Gnawing or burning upper abdominal pain that occurs 1 to 3 hours after a meal. The pain is worse when the stomach is empty and often disappears following ingestion of food.

Duodenal Ulcer Nighttime pain, nausea, and vomiting If the erosion progresses deeper into the mucosa, bleeding will occur Many duodenal ulcers heal spontaneously Most frequent in the 30- to 50-year-old age group,

Gastric Ulcers Less common Relieved by food, pain may continue even after a meal. Loss of appetite, weight loss, and vomiting Severe ulcers may penetrate through the wall of the stomach and cause death. More common in those older than age 60.

Inflammatory Bowel Disease Crohn’s disease Ulceration in the lower small intestine Ulcerative colitis erosions in the large intestine are called Treated with the anti-inflammatory medications discussed

Inflammatory Bowel Disease Particularly severe cases may require immunosuppressant drugs such as cyclosporine (Neoral, Sandimmune) or methotrexate (Folex, Mexate, others).

Gastroesophageal Reflux Disease (GERD) Acidic contents of the stomach move upwards into the esophagus. Intense burning known as heartburn May lead to ulcers in the esophagus. The cause usually a loosening of the sphincter located between the esophagus and the stomach.

Gastroesophageal Reflux Disease (GERD) Strongly associated with obesity, and losing weight may eliminate the symptoms. Many of the drugs prescribed for peptic ulcers are also used to treat GERD.

Concept Review 29.1 What are the similarities and differences between duodenal ulcers and gastric ulcers?

Core Concept 29.3 Peptic ulcer disease is treated by a combination of lifestyle changes and pharmacotherapy.

Drug Treatment H2-receptor blockers Antibiotics Proton-pump inhibitors Antacids Miscellaneous agents

Figure 29.4 Mechanisms of action of antiulcer drugs: (a) Proton-pump inhibitors act by blocking acid secretion by the HCl pump; (b) H2-receptor blockers act by decreasing acid secretion; (c) antibiotics act by removing H. pylori; (d) antacids act by neutralizingacids.

Table 29.1 (continued) Drugs for Peptic Ulcer Disease

Core Concept 29.4 Proton-pump inhibitors are effective at reducing gastric acid secretion.

Proton-Pump Inhibitors Act by blocking the enzyme responsible for secreting hydrochloric acid in the stomach Reduce acid secretion to a greater extent than do the H2-receptor blockers and have a longer duration of action. Drugs of choice for the treatment of PUD and GERD used only for the short-term control

Proton-Pump Inhibitors Heal more than 90% of duodenal ulcers within 4 weeks and about 90% of gastric ulcers in 6 to 8 weeks. Beneficial effects last 3 to 5 days after therapy is stopped

H2-receptor blockers reduce the secretion of gastric acid. Core Concept 29.5 H2-receptor blockers reduce the secretion of gastric acid.

H2 Receptor blocker H2-receptor - Responsible for increasing acid secretion in the stomach. Cimetidine (Tagamet), the first , and other drugs suppress the volume and acidity of stomach acid Also used to treat the symptoms of GERD.

H2 Receptor blocker Adverse effects minor Patients should be advised not to take antacids at the same time as H2-receptor blockers because the absorption of these drugs will be lessened.

Concept Review 29.2 Explain the following statement: All H2-receptor blockers are antihistamines, but not all antihistamines are H2-receptor blockers.

Core Concept 29.6 Antacids rapidly neutralize stomach acid and reduce the symptoms of peptic ulcer disease and GERD.

Antacids Alkaline, inorganic compounds of aluminum, magnesium, or calcium Combinations of aluminum hydroxide and magnesium hydroxide are the most common type.

Antacids Combination products combine antacids and H2-receptor blockers into a single tablet Simethicone – an antiflatulent, is sometimes added to antacid preparations it reduces gas bubbles that cause bloating and discomfort.

Core Concept 29.7 Antibiotics are administered to eliminate Helicobacter pylori, the cause of many peptic ulcers.

Antibiotics to Treat Helicobacter pylori Amoxacillin (Amoxil, others) Clarithromycin (Biaxin) Metronidazole (Flagyl) Tetracycline (Achromycin, others)

Core Concept 29.8 Several miscellaneous drugs are also beneficial in treating peptic ulcer disease.

Other Drugs to Treat Peptic Ulcer Disease Sucralfate (Carafate) Sucrose (a sugar) plus aluminum hydroxide (an antacid Produces a thick, gel-like substance Coats the ulcer, protecting it against further erosion and promoting healing.

Other Drugs to Treat Peptic Ulcer Disease Misoprostol (Cytotec) Prostaglandin-like substance Inhibits gastric acid secretion and stimulates the production of protective mucus

Other Drugs to Treat Peptic Ulcer Disease Metoclopramide (Reglan) Used for patients who fail to respond to first-line agents. More commonly prescribed to treat nausea/vomiting associated with surgery or cancer chemotherapy. Available by the oral, IM or IV routes.

Concept Review 29.3 Is peptic ulcer disease considered an infection, an inflammation, or both?

Laxatives are used to promote defecation. Core Concept 29.9 Laxatives are used to promote defecation.

Laxatives Bulk-forming Absorb water add to the size to the fecal mass Prevention and treatment of chronic constipation. Slow onset of action Not used when a rapid and complete bowel evacuation is necessary.

Laxatives Stimulant Promote peristalsis by irritating the bowel Rapid-acting More likely to cause diarrhea and cramping Should only be used occasionally may cause dependence and depletion of fluid & electrolytes.

Laxatives Saline/osmotic Cause water to be retained in the fecal mass Produce a bowel movement in 1-6 hours they should not be used on a regular basis possibility of fluid and electrolyte depletion.

Laxatives Stool softeners/surfactant Miscellaneous Cause more water and fat to be absorbed into the stools Used to prevent constipation Miscellaneous Act by mechanisms other than the above

Concept Review 29.4 Bismuth compounds are used to treat several digestive disorders. Describe these agents and their uses.

Opioids are the most effective drugs for controlling severe diarrhea. Core Concept 29.10 Opioids are the most effective drugs for controlling severe diarrhea.

Opiods for Treatment of Diarrhea Drugs of choice Rapid onset and effectiveness At doses used for diarrhea, opioids do not produce dependence or serious adverse effects

Opiods for Treatment of Diarrhea The most common opioid antidiarrheal is diphenoxylate (Lomotil), which is a Schedule V controlled substance. Loperamide (Imodium) is an opioid that carries no risk for dependence and is available OTC.

Core Concept 29.11 Antiemetics are prescribed to treat nausea, vomiting, and motion sickness.

Antiemetic Drugs Belong to a number of different classes Antipsychotics Antihistamines Serotonin-receptor blockers Glucocorticoids Benzodiazepines

Table 29.4 (continued) Selected Antiemetics

Core Concept 29.12 Anorexiants and lipase inhibitors are used for the short-term management of obesity.

Anti-obesity Drugs Sibutramine (Meridia) most widely prescribed short-term control of obesity suppresses appetite, probably by affecting the hunger center in the brain.

Anti-obesity Drugs Orlistat (Xenical). Blocks the enzyme lipase in the GI tract, which blocks the absorption of fats May also decrease absorption of other substances, including fat-soluble vitamins and coumadin

Core Concept 29.13 Pancreatic enzymes are administered as replacement therapy for patients with pancreatitis or malabsorption syndromes.

Pancreatic Enzyme Supplements Obtained from either pork or beef pancreas Contains the necessary enzymes to digest fats, carbohydrates, and proteins Pancrelipase (Cotazym, Pancrease, others) Has significantly more enzyme activity. Pancreatin (Entozyme, Viokase, others)