Lilley Chapter 40 - Antidiarrheal and Laxatives Flashcards
To avoid fecal impaction, psyllium (Metamucil®) should be administered with at least how many mL of fluid?
120 mL
180 mL
300 mL
240 mL
D. 240 mL
Bulk-forming laxatives such as psyllium must be given with at least 240 mL of liquid plus additional liquid each day to prevent esophageal obstruction and fecal impaction.
Bismuth subsalicylate (Pepto-Bismol®), as an adsorbent, has which mechanism of action?
Decreases intestinal motility and secretion
Binds to diarrhea-causing bacteria for excretion
Increases peristalsis by irritating the bowel
Promotes water absorption into the colon
B. Binds to diarrhea-causing bacteria for excretion
Adsorbent antidiarrheal medications bind to diarrhea-causing bacteria to form a nonabsorbable complex, which is then excreted in the stool.
What is the mechanism of action of diphenoxylate (Lomotil®)?
It inhibits intestinal excretion of water and sodium.
It prevents the reabsorption of water in the bowel.
It decreases peristalsis in the intestinal wall.
It increases intestinal secretion and motility.
C. It decreases peristalsis in the intestinal wall.
Diphenoxylate is an opiate antidiarrheal medication that acts on the smooth muscle of the intestinal tract to inhibit gastrointestinal (GI) motility and excessive propulsion of the GI tract (peristalsis).
How does magnesium hydroxide (Phillips Milk of Magnesia®) alleviate constipation?
It causes water absorption into the colon.
It directly irritates intestinal mucosa.
It allows more fat to be absorbed into the stool.
It absorbs water to increase bulk within the colon.
A. It causes water absorption into the colon.
Magnesium hydroxide is a saline laxative that increases osmotic pressure to draw water into the colon, producing a watery stool, usually within 3 to 6 hours of ingestion.
Related to its mechanism of action, what is an additive effect of lactulose?
Alleviating galactose intolerance
Reducing ammonia levels
Decreasing cerebral edema
Correcting sodium imbalances
B. Reducing ammonia levels
Lactulose draws water into the colon and produces a laxative effect. This drug-induced acidic environment also reduces blood ammonia levels by forcing ammonia from the blood into the colon. This effect is useful in treating patient with hepatic encephalopathy.
What potential adverse effect would lead the nurse to question the prescription of bismuth subsalicylate (Pepto-Bismol) as an antidiarrheal medication for a patient prescribed daily aspirin?
Constipation
Nausea
Urinary retention
Increased bleeding
D. Increased bleeding
The adsorbent bismuth subsalicylate is a form of aspirin, or acetylsalicylic acid; thus, it also has many of the same adverse effects as aspirin. Bismuth subsalicylate can lead to increased bleeding times and bruising when administered with warfarin as well as with aspirin and other nonsteroidal anti-inflammatory drugs.
A patient is prescribed the over-the-counter laxative magnesium hydroxide (Phillips Milk of Magnesia). Which condition in the client’s history would alert the nurse to discuss this medication with the patient and the health care provider?
Liver dysfunction
Renal insufficiency
Chronic constipation
Hypertension
B. Renal insufficiency
The magnesium saline laxatives are to be used with caution in patients with renal insufficiency, because they can be absorbed enough to cause hypermagnesemia. They are most commonly used for preparation of the bowel for diagnostic and surgical procedures.
