Gastrointestinal Motility (Laxatives/Antidiarrheals)

Question 1

Cholinomimetic Agents

Answer 1

-stimulate GI motility

Ex. Bethanechol
Use: post-op urinary retention

2. Neostigmine

Question 2

Metoclopramide

Answer 2

• dopamine receptor antagonist

- Effect on the esophagus and stomach

Question 3

Erythromycin

Answer 3

Uses: acute upper gastrointestinal hemorrhage to promote gastric emptying of blood before endoscopy

Question 4

Constipation treatment algorithm

Answer 4

• diet modification, add fiber
• Add osmotic laxative (ex. PEG) for 2-4 weeks
• Add stimulant laxative
• Lubriprostone or linaclotide

Question 5

Milk of magnesia

Answer 5

• Non absorbable salt
• osmotic laxative
• risk of hypermagnesemia in renal insufficiency

Question 6

Purgatives

Answer 6

• harsh, meant to force a bowel movement in 1-3 hours
• Ex. magnesium citrate, sodium phosphate

sodium phosphate ADE: hyperphosphatemia, hypocalcemia, hypernatremia, hypokalemia

Question 7

Polyethylene glycol (PEG)

Answer 7

Ex. Miralax

• great because it doesn’t cause cramps or flatus
• No significant electrolyte shifts since this is a balanced preparation

Question 8

Anthraquinone Derivatives

Answer 8

Ex. Aloe, senna, cascara

Chronic use: brown pigmentation of the colon “melanosis coli”**

Question 9

Acute versus Chronic diarrhea

Answer 9

Acute: <3 days
Chronic: >14 days

Question 10

Contraindications for antidiarrhea agents

Answer 10

• bloody diarrhea
• high fever
• systemic toxicity

Question 11

Bile Salt-Binding resins

Answer 11

Ex. chollestyramine, colestipol, or colesevelam

-can bind other drugs and reduce absorption

Question 12

Antisecretory: Ex. Octreotide

Answer 12

Ex. Somatostatin

-inhibits secretion of numerous hormones and transmitters

ADE: steatorrhea, fat-soluble vitamin deficiency