GI, Pharmacology - Lippincott's QA
A 45-year-old man who is obese complains of post- prandial epigastric pain. The pain does not appear after every meal. He has noticed the pain especially after eating spicy foods. He is not currently taking any medications. You suspect gastroesophageal reflux dis- ease (GERD) and want to try a drug that will lower the amount of acid in his stomach. Which of the following drugs chemically elevates the pH? (A) Aluminum hydroxide (B) Fexofenadine (C) Misoprostol (D) Omeprazole (E) Ranitidine
A: Aluminum hydroxide. Multiple factors contribute to acid secretion by parietal cells in gastric mucosa. Gastrin from G cells, histamine from enterochromaffin-like (ECL) cells (acting on H2 receptors), and acetylcholine from parasympathetic neurons all act directly on parietal cells to induce acid secretion. Prostaglandins from surface mucous cells and somatostatin from D cells directly inhibit acid secretion. Ranitidine is an H2-receptor antagonist, meaning it blocks the pro-acid effect of endogenous histamine. Aluminum hydroxide is a chemical base that raises the pH by the following reaction to produce water: H1 1 OH2 → H2O. (B) Fexofenadine is a second-generation H1 antagonist. It would not be expected to significantly bind H2 receptors. (C) Misoprostol is a prostaglandin agonist, not antagonist. It decreases acid by mimicking the inhibitory effect of endogenous prostaglandins. (D) Omeprazole does not bind a receptor. It decreases acid secretion by block- ing the proton pump on the lumenal surface of parietal cells. (E) Ranitidine is an H2 receptor blocker. H2 receptors are found on gastric parietal cells, and stimulation causes an increase in acid secretion.
A 33-year-old woman who is obese complains of postprandial, burning chest pain. Her physician prescribes pantoprazole. Pantoprazole may impair absorption of which of the following nutrients? (A) Calcium (B) Carbohydrates (C) Fatty acids (D) Vitamin A (E) Vitamin D
A: Calcium. Postprandial (after a meal) chest pain is most likely caused by gastroesophageal reflux disease (GERD), as in this case. The pain is caused by gastric acid irritating the lining of the esophagus. Pantoprazole helps the symptoms of GERD by decreasing the amount of gastric acid through inhibition of proton pumps. Raising the gastric pH in this manner may impair absorption of diva- lent cations such as magnesium and calcium. Some research suggests that prolonged use of proton pump inhibitors may increase the risk for bone fractures, although this relationship is uncertain. (B) Acarbose, a drug used to treat diabetes mellitus, blocks absorbtion of carbohydrates. Pantoprazole does not interfere with carbohydrate absorption. (C) Orlistat is a drug that impairs fatty acid absorption by inhibiting gastric and pancreatic lipases. Pantoprazole does not interfere with fatty acid absorption. (D) Vitamin A is a fat-soluble vitamin. Its absorption is decreased in cases of fat malabsorption. Pantoprazole does not interfere with vitamin A absorption. (E) Vitamin D is a fat-soluble vitamin. Its absorption is decreased in cases of fat malabsorption. Pantoprazole does not interfere with vitamin D absorption.
A 67-year-old woman with known peptic ulcer dis- ease found at endoscopy to be on maintenance treat- ment with misoprostol at 125% of the recommended dose. The rationale behind this dose is to maximize which of the following? (A) Decrease in gastric acid secretion (B) Improve bicarbonate balance (C) Improve gastric emptying (D) Improve sphincter tone of the lower esophagus (E) Lower gastric luminal pressures
A: Decrease in gastric acid secretion. Misoprostol, a stable analog of prostaglandin E1, as well as some PPIs, are approved for the prevention of gastric ulcers induced by NSAIDs. It is less effective than H2 antagonists and the PPIs for acute treatment of peptic ulcers. Although misoprostol has cytoprotective actions, it is clinically effective only at higher doses that diminish gastric acid secretion. (B) Misoprostol is an analog of prostaglandin E1 and does not affect bicarbonate balance. (C) Misoprostol does not improve gastric muscular tone. (D) Misoprostol does not alter lower esophageal sphincter tone. (E) Misoprostol does not change gastric luminal pressures.
A 57-year-old man with chronic gastroesophageal reflux disease on cimetidine presents to a new primary care physician. He states that he has been doing well and has been taking this medication for about 15 years. Which of the following statements is true about therapy with this agent? (A) Dose adjustment is required in hepatic failure (B) Has a long half-life (C) 70% inactivated in the liver (D) 30% excreted in the urine
A: Dose adjustment is required in hepatic failure. Cimetidine and the other H2 antagonists are given orally, distribute widely throughout the body (including into breast milk and across the placenta), and are excreted mainly in urine. Cimetidine normally has a short serum half-life, which is increased in renal failure. Approximately 30% of a dose of cimetidine is slowly inactivated by the liver's microsomal mixed- function oxygenase system (see p. 14) and can inter- fere in the metabolism of many other drugs. The other 70% is excreted unchanged in urine. The dosage of all these drugs must be decreased in patients with hepatic or renal failure. (B) Cimetidine has a short half-life. (C) Thirty percent of a dose of cimetidine is slowly inactivated in the liver. (D) Seventy percent of a dose of cimetidine is excreted unchanged in the urine.
A 43-year-old man with a history of peptic ulcer disease has developed hypersensitivity to H2 blockers. He now complains of worsening of his dyspepsia. Physical examination reveals mild tenderness on the midepigastric region. If misoprostol is prescribed to this patient, which of the following mechanisms of action would be most plausible for this agent? (A) Enhance mucosal resistance (B) Inhibition of gastrin secretion (C) Inhibition of proton pump secretion (D) Inhibition of somatostatin release (E) Inhibition of uric acid secretion
A: Enhance mucosal resistance. Miso- prostol is sometimes used to inhibit the secretion of gastric acid and to enhance mucosal resistance to injury in patients with gastric ulcer, who are chroni- cally taking nonsteroidal anti-inflammatory agents. Proton pump inhibitors, such as omeprazole, and H2 antihistamines also reduce the risk of gastric ulcer and are better tolerated than misoprostol, which induces intestinal disorders. (B) Misoprostol does not inhibit gastrin release. It does inhibit gastric acid secretion. (C) Proton pump inhibitors inhibit proton pump secretion. (D) Misoprostol does not inhibit somatostatin release. (E) Misoprostol does not inhibit uric acid secretion.
130 A 39-year-old woman with chronic migraine headaches manages her condition with ibuprofen 200 mg. Most days, she does well with 200 to 400 mg. Adverse reactions to this therapy include which of the following? (A) Gastrointestinal upset (B) Hives (C) Seizure disorder (D) Teratogenicity (E) Throat tightness
A: Gastrointestinal upset. The most common side effect of ibuprofen is gastrointestinal upset. Bleeding and rash are also common. Patients must be aware of these adverse effects. (B) Rash is more common than hives in patients taking ibuprofen. (C) Seizure disorder is uncommon in patients taking ibuprofen. (D) Teratogenicity is unlikely in patients taking ibuprofen. (E) Throat tightness is unexpected in patients taking ibuprofen.
A 42-year-old woman with irritable bowel syndrome with diarrhea predominance presents to her primary care physician for treatment. The physician suggests an exercise regimen, dietary modifications, and a bulk laxative. The likely mechanism of action of this agent would involve which of the following? (A) Gel formation in the intestine (B) Neuromodulation of the S3 nerve root (C) Nonabsorbable salt (D) Osmotic laxative (E) Stimulation of the cholinergic nervous system
A: Gel formation in the intestine. Bulk laxatives include hydrophilic colloids. They form gels in the large intestine that cause water retention and intestinal distension, which increases peristalsis. This agent should be used with caution because of the potential for intestinal obstruction. (B) Sacral nerve stimulation is a surgical procedure that stimulates the S3 nerve root. (C) Magnesium citrate is a nonabsorb- able salt. (D) Lactulose is a semisynthetic sugar that also acts as an osmotic diuretic. (E) Cholinomimetic agents stimulate the cholinergic nervous system.
A 49-year-old man with a history of peptic ulcer dis- ease and gastroesophageal reflux disorder is being treated with cimetidine for approximately 20 years. He now complains of breast swelling and breast discharge. What is the most likely explanation for these findings? (A) Abscess (B) Antiandrogenic effect (C) Inflammatory response (D) Neoplastic process (E) Overwhelming edema
B: Antiandrogenic effect. Cimetidine can also have endocrine effects because it acts as a nonsteroidal antiandrogen. These effects include gynecomastia and galactorrhea (continuous release/discharge of milk). Drugs such as ketoconazole, which depend on an acidic medium for gastric absorption, may not be efficiently absorbed if taken with one of these H2 receptor antagonists. (A) Cimetidine is associated with endocrine effects such as breast swelling and tenderness. This is not caused by an abscess. (C) This process is not inflammatory in nature. This process is an endocrine side effect of cimetidine. (D) This patient has no evidence by history of examination to suggest breast cancer. (E) This is an overgrowth of breast tissue, not a buildup of interstitial fluid in the chest.
A 78-year-old woman with osteoporosis and occa- sional gastroesophageal reflux presents to her primary care physician for follow-up. Physical examination of the heart, lungs, and abdomen are unremarkable. Which of the following agents would be best to treat both of her underlying conditions? (A) Aluminum hydroxide (B) Calcium carbonate (C) Magnesium hydroxide (D) Sodium bicarbonate (E) Warm milk
B: Calcium carbonate. Aluminum- and magnesium-containing antacids are used for symptomatic relief of peptic ulcer disease and GERD, and they may also promote healing of duodenal ulcers. However, they are used as last-line therapy for acute gastric ulcers because the evidence for efficacy is less compelling. Calcium carbonate preparations are also used as calcium supplements for the treatment of osteoporosis. (A) Aluminum hydroxide will help with the GERD symptoms but not the osteoporosis. (C) Magnesium hydroxide will help with the GERD symptoms but will not improve bone mineralization as needed in osteoporosis. (D) Sodium bicarbonate is an effective antacid but is not of benefit in the treatment of osteoporosis. (E) Warm milk may worsen gastroesophageal reflux and will have limited benefit for osteoporosis.
A 34-year-old man with a sacral spinal cord injury has neurogenic bowel. He is on a bowel regimen that involves periodic bowel cleansing with soapsuds enemas. He is given a trial of bethanechol for this condition. Which of the following adverse events must his treating physician be aware of? (A) Bronchodilation (B) Diarrhea (C) Dry mouth (D) Dry skin (E) Sigmoid colonic stasis
B: Diarrhea. Bethanechol causes the effects of generalized cholinergic stimulation. These include sweating, salivation, flushing, decreased blood pressure, nausea, abdominal pain, diarrhea, and bronchospasm. Atropine sulfate may be administered to overcome severe cardiovascular or bronchoconstrictor responses to this agent. (A) Bronchoconstriction or bronchospasm can result from cholinergic nervous system stimulation. (C) Dry mouth is a side effect from anticholinergic medications. Salivation is a side effect from cholinomimetic agents. (D) Dry skin can occur with anticholinergic agents. (E) Sigmoid colon stasis can occur with anticholinergic agents. This can lead to constipation.
A 64-year-old woman is hospitalized for COPD exacerbation. While in the hospital, she becomes constipated. She also takes metoprolol for hypertension and mirtazapine for depression. The physician gives her docusate. Which of the following adverse reactions is most likely to occur as a result of docusate administration in this patient? (A) Cardiac arrhythmia (B) Diarrhea (C) Hypertension (D) Rash (E) Worsening depression
B: Diarrhea. Docusate is simply a stool softener. It is used to treat constipation and is gener- ally well tolerated and has few interactions or side effects. One of its few side effects is that too high a dose can cause diarrhea. Docusate does not interact with metoprolol or mirtazapine, so this case of diar- rhea cannot be attributed to an interaction between her medications. (A) Too much metoprolol can cause AV block, but neither docusate alone nor docusate with metoprolol is known to cause arrhythmias. Of the adverse reactions listed, diarrhea is the most likely to be caused by docusate. (C) A drop in this patient's metoprolol level may result in hypertension, but this is unlikely because docusate does not interact withmetoprolol. Of the adverse reactions listed, diarrhea is the most likely to be caused by docusate. (D) There are many drugs that can cause a skin rash, but docusate is not one of them. Of the adverse reactions listed, diarrhea is the most likely to be caused by docusate. (E) If docusate decreased mirtazapine lev- els, depression may result, but this is not known to happen. Of the adverse reactions listed, diarrhea is the most likely to be caused by docusate.
A 27-year-old man complains of occasional heartburn. His physician makes a few suggestions of diet and life- style changes he could make as well as some medica- tions he can take for symptom management. The patient decides to try a magnesium hydroxide (MgOH) preparation. Which of the following is a side effect of MgOH that the physician should warn him about? (A) Constipation (B) Diarrhea (C) Headache (D) Impotence (E) Seizures
B: Diarrhea. Magnesium hydroxide is a base that neutralizes gastric acid. The reaction produces magnesium and chloride ions. The magne- sium is not absorbed by the intestine and acts as an osmolyte to retain water in the lumen. This results in increased volume and gut motility that can lead to diarrhea. (A) Magnesium hydroxide is also used to treat constipation because magnesium stays in the gut lumen as an osmolyte. Aluminum hydroxide is a drug used to treat heartburn that can cause con- stipation. (C) Cimetidine is a drug used to treat heartburn that causes headache in about 3% of people. It is an H2 blocker usually used to treat more severe cases of heartburn than in this patient. Magnesium hydroxide is not known to cause head- aches. (D) Some of the H2 blockers, including cimetidine and ranitidine, can cause impotence. Magnesium hydroxide is not known to cause impotence. (E) Seizure is a rare complication of both famotidine and lansoprazole. Magnesium hydroxide is not known to cause seizures
A 47-year-old immigrant from Japan with a long history of untreated gastric ulcers develops stomach cancer. One drug in his initial treatment regimen is 5-fluorouracil (5-FU) as well as ondansetron to control nausea. While receiving this drug, the patient develops redness and numbness on the palms of his hands and soles of his feet. How can this reaction be avoided? (A) Do not coadminister ondansetron with 5-fluorouracil (B) Give 5-FU by bolus rather than continuous infusion (C) Give5-FUbycontinuousinfusionratherthanbolus (D) Give with leucovorin (E) This is a rare, bizarre side effect of 5-FU and cannot be avoided
B: Give 5-FU by bolus rather than continuous infusion. Palmar-plantar erythrodysesthesia, or hand- foot syndrome, is a common reaction with many chemo- therapy drugs such as 5-FU. The exact mechanism is unclear, but excessive friction (as with walking and working with hands) and high temperatures seem to make it worse. Hand-foot syndrome is more commonly associated with continuous infusion of 5-FU than with bolus administration, so giving the drug by bolus helpsto avoid it. (A) Ondansetron and 5-FU are not known to interactions adversely. (C) Giving 5-FU by continuous infusion increases the likelihood that the patient will develop hand-foot syndrome. (D) Leucovorin, or folinic acid, can perform the same role as folic acid in DNA synthesis. Leucovorin is used to decrease toxicity of methotrexate, which inhibits folic acid recycling. Leucovorin is not known to protect against hand-foot syndrome caused by 5-FU. (E) Hand-foot syndrome is a common side effect of 5-FU administration, with some reports describing 50% of treated patients being affected. The likelihood of developing hand-foot syndrome can be lessened by giving 5-FU as a bolus rather than con- tinuous infusion.
A 47-year-old man with a history of NSAID-induced ulcers has been placed on sucralfate. He has been on the medicine for 1 year and does complain of inter- mittent chest pressure after meals. Upper endoscopy is performed. Which of the following findings is most likely to occur? (A) Duodenitis (B) Duodenal perforation (C) Gastric ulcers that appear unhealed (D) Normal gastric epithelium (E) Normal lower esophageal epithelium
C: Gastric ulcers that appear unhealed. Sucralfate should not be administered with PPIs, H2 antagonists, or antacids. Little of the drug is absorbed systemically. It is very well tolerated, but it can interfere with the absorption of other drugs by binding to them. This agent does not prevent NSAID-induced ulcers, and it does not heal gastric ulcers. (A) NSAID-induced ulcers are typically gastric and less likely to be duodenal. (B) Duodenal perforation would present with peritoneal signs and significant abdominal pain. (D) Normal gastric epithelium is unlikely to be present because active ulceration would be expected. (E) The lower esophagus likely has inflammatory changes.
A 58-year-old male is hospitalized for COPD exacerbation. While in the hospital, he becomes constipated. He has a history of hyperlipidemia and gout. The physician gives him docusate. How does docusate work to relieve constipation? (A) Binds water in the lumen (B) Increases chloride secretion into the gut lumen (C) Increases water absorption by the stool (D) Irritation of the bowel mucosa to stimulate peristalsis (E) Stimulation of the myenteric plexus
C: Increases water absorption by the stool. Constipation can have many causes, ranging from decreased gut motility to altered stool consistency. It can often be relieved by modifying one of these factors. Docusate is a surfactant and allows water and lipids to penetrate, bulk up, and soften stool without directly stimulating peristalsis. Docusate is therefore classified as a stool softener, not a laxative. (A) Agents such as polycarbophil and psyllium draw water into the gut lumen to increase the bulk and water content of the stool. Docusate works simply by allowing water to easily enter the stool itself. (B) This response describes the effect of lubiprostone (and cholera toxin). Docusate works simply by allow- ing water to easily enter the stool itself. (D) A soap- suds enema works in part by irritating the bowel mucosa to stimulate peristalsis. Docusate works simply by allowing water to easily enter the stool itself. (E) Docusate does not directly stimulate the myenteric plexus. By allowing water to easily enter the stool, however, docusate does cause an increase in stool bulk that leads to increased motility.
A 38-year-old businessman is on a trip to Mexico when he develops diarrhea. He has to give a presentation in a few hours and needs rapid relief. He takes an antidiarrheal preparation containing loperamide. Which of the following is a property of loperamide that makes it useful in treating diarrhea? (A) Anticholinergic (B) Broad-spectrum antibiotic (C) Gram-negative antibiotic (D) Inhibitor of myenteric plexus activity (E) Sympathetic nervous system stimulant
D: Inhibitor of myenteric plexus activity. Loperamide is an opioid-receptor agonist but does not affect the central nervous system. It binds to m-receptors on the myenteric plexus and, like other opioids, decreases myenteric plexus activity. By inhib- iting the myenteric plexus, GI smooth muscle activity is decreased. Stool transit time is increased, and it is thought that this allows more time for water absorp- tion from the feces to decrease diarrhea. (A) Atropineis an example of an anticholinergic that can be used to treat diarrhea. Loperamide does not influence signaling with acetylcholine. (B) Many antidiarrheals (including loperamide) have no antibiotic capability. They simply increase transit time in the bowels to allow for more water reabsorption. (C) This agent is not an antibiotic. (E) Clonidine is an example of a sympathetic nervous system stimulant that can be used for diarrhea. Data are limited as to its efficacy in treating diarrhea, and it is usually only used in refractory cases. Loperamide does not treat diarrhea by modulating sympathetic nervous system activity
119 A 58-year-oldmanwithahistoryofoccasionalGERD presents to the clinic with diarrhea for the past 3 months. He has not been sick and feeling quite well otherwise. Further history uncovers that 3 months ago, he switched the type of antacid he uses for reflux. He stopped the antacid and calls back 1 month later, saying he has not had diarrhea since then. Which of the following antacids was most likely causing the patient's diarrhea? (A) Aluminum hydroxide (B) Bismuth (C) Calcium carbonate (D) Magnesium hydroxide (E) Sodium bicarbonate
D: Magnesium hydroxide. Of the antacids listed, magnesium hydroxide is the most likely to cause diarrhea. Magnesium is poorly absorbed by the intestinal tract, so it draws water into the feces. When water is added to magnesium hydroxide, it is known as milk of magnesia, which is used as a laxative. (A) Aluminum hydroxide is more likely to cause constipation than diarrhea. (B) Bismuth can lead to darker colored stools but is not likely to cause diarrhea. (C) Calcium carbon- ate is more likely to cause constipation than diarrhea. (E) Sodium bicarbonate is more likely to cause side effects involving the kidneys and cardiovascular system and has little effect on stool quality.
A 48-year-old male presents to the emergency department with chest pain for the past 2 days. The pain is non-radiating and burning in nature. An ECG is normal, and serial troponins are negative. The physician makes the diagnosis of GERD. What is the most potent therapy for the prevention of GERD? (A) Bismuth (B) Famotidine (C) Misoprostol (D) Omeprazole (E) Pirenzepine
D: Omeprazole. The mechanism of action of omeprazole is irreversible inhibition of H1/K1-ATPase in parietal cells. The secretion of H1 is the last step in acid secretion, and therefore, the irreversible inhibition of this step is the most potent therapy for gastric acid reduction. (A) Bismuth does not pre- vent the formation of gastric ulcers. Its mechanism of action is to bind to the base of the ulcer and allowing bicarbonate secretion to neutralize stomach pH. (B) Famotidine is a reversible inhibitor of H2 receptors, which decreases the production of gastric acid. It is not as potent as omeprazole. (C) Misoprostol is a prostaglandin E1 analog that, at high doses, decreases the production of gastric acid. It is not as potent as omeprazole. (E) Pirenzepine blocks muscarinic (M1 and M3) receptors to decrease gastric acid production. It is not as potent as omeprazole.
A 45-year-old male who is obese presents to his primary care physician complaining of postprandial epigastric pain. The pain does not appear after every meal. He has noticed the pain especially after eating spicy foods and oatmeal. He is not currently taking any medications. Which of the following drugs prevents acid secretion by antagonizing a receptor? (A) Aluminum hydroxide (B) Fexofenadine (C) Misoprostol (D) Omeprazole (E) Ranitidine
E: Ranitidine. Multiple factors contribute to acid secretion by parietal cells in gastric mucosa. Gastrin from G cells, histamine from enterochromaffin- like (ECL) cells (acting on H2 receptors), and acetylcho- line from parasympathetic neurons all act directly on parietal cells to induce acid secretion. Prostaglandins from surface mucous cells and somatostatin from D cells directly inhibit acid secretion. Ranitidine is an H2- receptor antagonist, meaning it blocks the proacid effect of endogenous histamine. (A) Aluminum hydroxide does not bind a receptor. It is a base that decreases acid by a simple chemical reaction: H1 1 OH2 → H2O. (B) Fexofenadine is a second-generation H1 antagonist. It would not be expected to significantly bind H2 recep- tors. (C) Misoprostol is a prostaglandin agonist, not antagonist. It decreases acid by mimicking the inhibitory effect of endogenous prostaglandins. (D) Omeprazole does not bind a receptor. It decreases acid secretion by blocking the proton pump on the luminal surface of parietal cells.
A 37-year-old man with gastroesophageal reflux takes over-the-counter cimetidine. He has no health care insurance and thus does not go to see a physician. This patient must be aware of which of the following side effects of this medication? (A) Confusion (B) Constipation (C) Hallucinations (D) Headache (E) Muscular pain
E: Muscular pain. The adverse effects of cimetidine are usually minor and are associated mainly with reduced gastric acid production, the major pharmacologic activity of the drug. Side effects occur only in a small number of patients and gener- ally do not require discontinuation of the drug. The most common side effects are headache, dizziness, diarrhea, and muscular pain. Other central nervous system effects (such as confusion and hallucinations) occur primarily in elderly patients and after intrave- nous administration. (A) Confusion is common in elderly patients after IV infusion of cimetidine. (B) Diarrhea is a common side effect of cimetidine. (C) Hallucinations are common in elderly patients after IV infusion of cimetidine. (D) Headache is a common side effect of nearly all medications.
A 37-year-old man complains of chest pain after meals. He says this pain has gone on for a few months and gets only minimal relief from antacid tablets. The physician prescribes a drug that will decrease the amount of acid secreted by binding to and inhibiting an ATPase on the lumenal surface of parietal cells. Which of the following drugs works by this mechanism? (A) Atropine (B) Cimetidine (C) Misoprostol (D) Octreotide (E) Omeprazole
E: Omeprazole. The ATPase on the lumenal surface of parietal cells described in the ques- tion stem is known as the "proton pump." It uses energy from ATP cleavage to force hydrogen ions out of the cell and potassium ions in. The proton pump inhibitors generally have the -prazole suffix, as in omeprazole. These drugs bind to and inhibit the function of the H1/K1 ATPase to significantly reduce acid secretion. (A) Atropine decreases gastric acid secretion by blocking acetylcholine signaling from the vagus nerve to parietal cells. It is not commonly used to treat GERD because of its systemic anticholinergic side effects. (B) Cimetidine decreases gastric acid secretion by blocking histamine signaling from ECL cells to parietal cells. It blocks the H2 receptor. (C) Misoprostol is a prostaglandin analog. Prostaglandins inhibit acid secretion by binding GI receptors, which lead to a decrease in intracellular cAMP and in turn to decreased H1/K1 ATPase activity. They do not bind directly to the proton pump. (D) Octreotide is a somatostatin analog. Although it would decrease gastric acid production, it is not used to treat GERD because of its systemic side effects.
A 34-year-old construction worker injured his right leg while on the job. His medical history includes poorly controlled Type-2 diabetes mellitus. He now presents with cellulitis in his right leg, for which he is given empiric IV vancomycin. He also complains of nausea, for which he is given an antiemetic. Which of the following antiemetics is also an antihistamine? (A) Droperidol (B) Famotidine (C) Loratadine (D) Ondansetron (E) Promethazine
E: Promethazine. There are many receptor types that can be manipulated to decrease nausea. Promethazine is a phenothiazine-like chlorpromazine but has a much lower affinity for dopamine receptors and as such is not used as a neuroleptic. Its primary action is to antagonize H1 receptors, although its anti- emetic properties appear to be related to its central anticholinergic effects. (A) Droperidol is a neuroleptic similar to haloperidol. It can also relieve nausea and vomiting. Droperidol blocks many receptors, primarily dopamine. It does not block histamine receptors. (B) Famotidine is an H2 antagonist. It is used to treat GERD by inhibiting gastric acid secretion. Famotidine is not an antiemetic. (C) Loratadine is a second- generation H1 antagonist. Loratadine is an antihistamine used to treat allergic rhinitis and urticaria. It is not an antiemetic. (D) Ondansetron is an antiemetic that works by antagonizing 5-HT3 receptors both centrally and peripherally. It does not antagonize histamine receptors.
A 24-year-old man complains of recurring episodes of bloody diarrhea and abdominal pain. A flexible sigmoidoscopy reveals pseudopolyps and erythema- tous, friable mucosa. One of the drugs given to this patient is diphenoxylate. How could diphenoxylate help this patient? (A) Antimicrobial effects (B) Blocks TNF-a signaling (C) Inhibition of dihydrofolate reductase (D) Inhibition of phospholipase A2 (E) Slows peristalsis
E: Slows peristalsis. This patient's presentation suggests ulcerative colitis, a type of inflammatory bowel disease. Pharmacotherapy for ulcerative colitis involves multiple drugs to treat various aspects of the disease. In cases of mild ulcerative colitis, the frequent diarrhea may be the chief concern. Diphenoxylate may be used in such cases to slow gut motility. (A) Sulfapyridine is an antimicrobial often administered as a compound with mesalamine called sulfasalazine. Diphenoxylate does not possess antimicrobial properties. (B) Many biologics used in the treatment of ulcerative colitis, such as infliximab, bind up TNF-a to prevent its signaling. Diphenoxylate does not block TNF-a signaling. (C) Methotrexate is an inhibitor of dihydrofolate reductase used as an immunosuppressant to treat moderate cases of ulcerative colitis. Diphenoxylate does not inhibit dihydrofolate reductase. (D) Glucocorticoids work in part by increasing lipocortins, which block phospholipase A2, impairing the inflammatory cells' ability to make prostaglandins. Diphenoxylate does not inhibit phospholipase A2.
