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18 Cards in this Set
- Front
- Back
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How do stool softeners work?
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They allow additional water and fats to be absorbed into the stool, making it easier to move along; surface activating agents become emulsified with the stool to produce softer feces and ease of passage
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What is the prototype drug name for stool softeners/surfactans?
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Dioctyl sodium, Sulfosuccinate [Docusate]
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Castor oil needs what enzyme to activate its active ingredient?
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Rincinoleic acid is activated in the small bowel by pancreatic lipase
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How does castor oil work?
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Castor oil is broken down in the small intestine to rincinoleic acid, which is very irritatin got the gut and promptly increases peristalsis; works "fast and furious"
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A patient has a deficiency in pancreatic lipase. Which laxative will not work?
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Castor oil; inability to activate ricinoleic acid by lipase
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How do anthraquinones (cascara and senna) work?
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They contain emodin which stimulates colonic activity; rely on bacteria for activation
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Where must phenolphthalines and biscadoyl be absorbed and eliminated to work?
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Absorbed into the blood and eliminated in the bile as the active glucuronide
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Which drugs won't work in patients with bile duct obstruction or in patients taking bile binding resins (cholestyramine)?
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Phenolpthalines and bisacodyl
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How does lubiprostone work?
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It is a laxative which activates secretory chloride channels on the apical epithelium of the small intestine; it doesn't have to be absorbed to work
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How does liquid petrolatum and mineral oil work?
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Lubricates feces and coats intestinal wall with water repellent film that prevents dehydration of fecal matter
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How does dietary fiber work?
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Increases stool weight via
1. absorption of water 2. produces voltaile fatty acids 3. prevents reabsorptipon of bile acids (which has a secretory effect) |
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How do ionic salts promote the passage of stool?
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Nonabsorbale salts that hold water in the intestine by osmosis and distent the bowel, increasing intestinal activity and producing defecation in about one hour - fast and furious
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How do nonabsorbale sugars work?
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Pull water into lumen by osmosis, poorly absorbed; ex) lactulose, polythylene glycol, lactose in lactase deficient patients and sorbitol
Continous liquid diarrhea! |
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How can the antibiotic erythromycin treat constipation?
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Motilin agonist on cholinergic motor neurons
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Which medications areused after surgery to stimulate bowel movements?
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Neostigmine; prevents Ach breakdown to increase Ach stimulation; often seen in Parkinson's patients
Bethanechol; stimulates smooth muscle cells to stimulate bowel movement AFTER SURGERY (muscarinic agonist) |
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How can oral nalaxone be used to treat constipation?
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Opiod antgaonist so promotes motility; if given orally it does not reverse the analgesic effect of oycodone
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What are the two oral opiod antagonists?
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Oral nalaxone; almivopan
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What is the one subcutaneously injected opiod antagonist?
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Methylnaltrexone
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