Sketchy Pharm: Laxatives & Antidiarrheal Agents

Question 1

What are the two main magnesium-containing osmotic diuretics?

Answer 1

Magnesium citrate and magnesium hydroxide

Question 2

_________ is often used in pre-op settings to clean out the colon.

Answer 2

Polyethylene glycol

Question 3

How does lactulose work?

Answer 3

It acidifies the colon and traps NH3 (as NH4+).

Question 4

____________ is used in killing the bacteria that generate NH3 in hepatic encephalopathy. Why?

Answer 4

Rifaximin

Question 5

How does docusate work?

Answer 5

It is a surfactant that facilitates water penetration into the stool (think of the water-logged canoe at the DOCk).

Question 6

Chronic use of ______________ can lead to characteristic darkening of the colon.

Answer 6

senna –this effect is called melanosis coli

Think of the senna sun tan.

Question 7

What are two contraindications of antidiarrheal use?

Answer 7

Bloody diarrhea and fever

Question 8

What does stimulation of the mu-opioid receptors do?

Answer 8

It increases segmentation, thus increasing colonic transit time.

Question 9

True or false: the opioid-based antidiarrheals cannot cross the blood-brain barrier.

Answer 9

Loperamide cannot, but diphenoxylate can.

Question 10

Two bulk-forming laxatives are _______________.

Answer 10

methylcellulose and psyllium; both are large molecules that are unabsorbed by the GI tract. They can also absorb large amounts of water

Question 11

Somatostatin can be used to treat the secretory diarrhea found in ______________.

Answer 11

VIPomas and carcinoid syndrome