Agents Affecting GI Motility

Question 1

Which antidiarrheal coats the lining of the GI tract and soothes irritation, preventing stimulation of local reflexes that cause excessive GI activity and diarrhea?

Answer 1

Bismuth subsalicylate (Pepto-Bismol)

Question 2

AE of Bismuth subsalicylate (Pepto-Bismol):

Answer 2

Black coating on the tongue

Question 3

Patients with what type of failure should avoid taking Bismuth subsalicylate (Pepto-Bismol)?

Answer 3

Renal failure

Question 4

Which antidiarrheal is a Mu agonist that does not cross the BBB, slows peristalsis and allows increased time for absorption of fluid and electrolytes?

Answer 4

Loperamide (Imodium)

Question 5

Because of Loperamide (Imodium)’s action at the Mu receptor what might a patient develop?

Answer 5

Physical dpendence

Question 6

AE of Loperamide (Imodium):

Answer 6

N/V, abdominal pain, bloating

Question 7

Opium derivatives (paregoric) do what to prevent diarrhea?

Answer 7

Inhibit peristalsis

Question 8

How do bulk forming laxatives like Metamucil and FiberCon work?

Answer 8

• Causes the fecal matter to increase in bulk
• Increase GI motility by increasing fluid in the GI tract
• Stimulate stretch receptors

Question 9

What type of laxatives are Senna (Senokot), Bisacodyl (Dulcolox), Castor oil, and mineral oil?

Answer 9

Stimulant laxatives

Question 10

How do stimulant laxatives work?

Answer 10

-Direct action on the intestinal mucosa
-Stimulate myenteric plexus
Alter water and electrolyte secretions

Question 11

How do the onset of action between Senna (Senokot) and Bisacodyl (Dulcolox) differ?

Answer 11

Senna: 6-10hrs
Dulcolox: 15-60mins

Question 12

Castor oil: type of laxative, onset of action, when CI

Answer 12

Stimulant
2-6hrs
Pregnant women

Question 13

Which stimulant laxative lines the GI tract, prevents absorption of water and electrolytes, and has an onset of action of 6-8hrs?

Answer 13

Mineral oil

Question 14

Which type of laxatives work by retaining water in the the intestinal lumen, increasing intraluminal pressure, and causing CCK release?

Answer 14

Saline and Osmotic laxatives

Question 15

When are saline and osmotic laxatives used?

Answer 15

Prep for surgery/colonoscopy

Evacuate bowel in ~3hrs

Question 16

Name some saline and osmotic laxatives:

Answer 16

Magnesium salts (Epsom salt)
Milk of Magnesia 
Magnesium hydroxide
Magnesium citrate
Sodium phosphate (enema)
Lactulose 
Glycerin
Sorbitol

Question 17

How do surfactants/stool softeners work and examples?

Answer 17

-Detergent activity
-Facilitates water to soften stool
Docusate sodium (Colace)
Docusate calcium (Surfak)

Question 18

When are surfactant/stool softeners often used and in combo with what other drug?

Answer 18

Post-op

In combination with Senna (stimulant lax)

Question 19

What condition is Linaclotide (Linzess) used for and how does it work?

Answer 19

IBS with constipation
Stimulates intestinal fluid secretion and transit
(long-term risks unknown)

Question 20

What condition is Lubiprostone used for and how does it work?

Answer 20

IBS with constipation

Locally acting chloride channel activated that enhances chloride-rich intestinal fluid secretion