Home Books Katzung & Trevor's Pharmacology: Examination & Board Review, 12e

Chapter 59: Drugs Used in Gastrointestinal Disorders

A 55-year-old woman with type 1 diabetes of 40 years’ duration complains of severe bloating and abdominal distress, especially after meals. Evaluation is consistent with diabetic gastroparesis. Which of the following is a prokinetic drug that could be used in this situation?

(A) Alosetron

(B) Cimetidine

(C) Loperamide

(D) Metoclopramide

(E) Sucralfate

Of the drugs listed, only metoclopramide is considered a prokinetic agent (ie, one that increases propulsive motility in the gut). The answer is D. Alosetron is a 5HT₃ receptor blocker, cimetidine is a H₂ receptor blocker, loperamide is an opioid, and sucralfate forms a protective layer over an ulcer.

A patient who is taking verapamil for hypertension and angina has become constipated. Which of the following drugs is an osmotic laxative that could be used to treat the patient’s constipation?

(A) Aluminum hydroxide

(B) Diphenoxylate

(C) Magnesium hydroxide

(D) Metoclopramide

(E) Ranitidine

A laxative that mildly stimulates the gut would be most suitable in a patient taking a smooth muscle relaxant drug such as verapamil. By holding water in the intestine, magnesium hydroxide provides additional bulk and stimulates increased contractions. A helpful mnemonic is magnesium “magnifies” stool, aluminum hALts the stool. The answer is C. Diphenoxylate is an opioid receptor agonist, metoclopramide is a prokinetic agent, ranitidine is a H₂ receptor blocker.

A 40-year-old male CEO came to the emergency department with severe burning chest pain radiating into his neck. His electrocardiogram was normal and test for troponin was negative. A diagnosis of GERD was made and he was sent home with a prescription for a drug that inhibits stomach acid. Which of the following is a drug that irreversibly inhibits the H⁺/K⁺ ATPase in the parietal cells?

(A) Cimetidine

(B) Diphenoxylate

(C) Esomeprazole

(D) Metoclopramide

(E) Sulfasalazine

Esomeprazole, the (S) isomer of omeprazole, is a prodrug converting spontaneously in the parietal cell canaliculus to a sulfonamide that irreversibly inactivates the proton pump. The answer is C.

A 25-year-old college student went to student health care center for severe cramps, diarrhea, fever, and weight loss. She was diagnosed with Crohn’s disease. Which drug is most likely to be useful in the treatment of her inflammatory bowel disease?

(A) Diphenhydramine

(B) Diphenoxylate

(C) Mesalamine

(D) Ondansetron

(E) Ursodiol

Mesalamine is a form of 5-aminosalicylic acid that is active in the large intestine and thereby provides a local anti-inflammatory effect that is useful in Crohn’s disease, a form of inflammatory bowel disease. The answer is C.

A 34-year-old woman has irritable bowel syndrome with diarrhea that is not responsive to conventional therapies. Despite the small risk of severe constipation and ischemic colitis, the patient decides to begin therapy with alosetron. Alosetron has which of the following receptor actions?

(A) 5-HT₃ receptor antagonist

(B) 5-HT₄ receptor agonist

(C) D₂ receptor antagonist

(D) NK₁ receptor antagonist

(E) Muscarinic receptor antagonist

Serotonin plays a major regulatory role in the enteric nervous system, and the potent 5-HT₃ receptor antagonist alosetron has shown efficacy in treating women with IBS that is accompanied by diarrhea. The answer is A.

On your way to an examination, you experience the vulnerable feeling that an attack of diarrhea is imminent. If you stopped at a drugstore, which one of the following antidiarrheal drugs could you buy without a prescription even though it is related chemically to the strong opioid analgesic meperidine?

(A) Aluminum hydroxide

(B) Diphenoxylate

(C) Loperamide

(D) Magnesium hydroxide

(E) Metoclopramide

Aluminum hydroxide is constipating but is not related chemically to meperidine; magnesium hydroxide is a strong laxative. The 2 antidiarrheal drugs that are structurally related to opioids are diphenoxylate and loperamide. Loperamide is available over-the-counter; diphenoxylate is mixed with atropine alkaloids, and the product (Lomotil, others) requires a prescription. The answer is C.

A 45-year-old man with a duodenal ulcer was treated with a combination of drugs intended to heal the mucosal damage and to eradicate Helicobacter pylori. Which of the following antibacterial drugs is used commonly to eradicate intestinal H pylori?

(A) Cefazolin

(B) Ciprofloxacin

(C) Clarithromycin

(D) Clindamycin

(E) Vancomycin

The macrolide antibiotic clarithromycin is commonly used in antibiotic regimens designed to treat duodenal ulcers caused by H pylori. The other antibiotics that are used include amoxicillin, tetracycline, and metronidazole. Bismuth also has an antibacterial action. The answer is C.

A patient is receiving highly emetogenic chemotherapy for metastatic carcinoma. To prevent chemotherapy-induced nausea and vomiting, she is likely to be treated with which of the following?

(A) Levodopa

(B) Methotrexate

(C) Misoprostol

(D) Ondansetron

(E) Sucralfate

The 5-HT₃ receptor antagonists are highly effective at preventing chemotherapy-induced nausea and vomiting, which can be a dose-limiting toxicity of anticancer drugs. The answer is D.

The following matching questions consist of a list of lettered options followed by several numbered items. For each numbered item, select the ONE option that is most closely associated with it.

Which drug stimulates chloride secretion into the gut lumen and is used for irritable bowel syndrome?

(A) Aluminum hydroxide

(B) Balsalazide

(C) Castor oil

(D) Cimetidine

(E) Dexamethasone

(F) Methotrexate

(G) Metoclopramide

(H) Mineral oil

(I) Omeprazole

(J) Linaclotide

(K) Pancrelipase

(L) Sucralfate

Linaclotide is approved for the treatment of chronic constipation and IBS with predominant constipation. Linaclotide activates guanylyl cyclase-C on the luminal intestinal epithelial surface, which leads to activation of the cystic fibrosis transmembrane conductance regulator (CFTR) leading to increased chloride-rich secretion and acceleration of intestinal transit. The answer is J.

The following matching questions consist of a list of lettered options followed by several numbered items. For each numbered item, select the ONE option that is most closely associated with it.

This is a small molecule that polymerizes in stomach acid and coats the ulcer bed, resulting in accelerated healing and reduction of symptoms.

(A) Aluminum hydroxide

(B) Balsalazide

(C) Castor oil

(D) Cimetidine

(E) Dexamethasone

(F) Methotrexate

(G) Metoclopramide

(H) Mineral oil

(I) Omeprazole

(J) Linaclotide

(K) Pancrelipase