GI Phamacology

Question 1

Phenothiazines

Answer 1

1st line nausea tx.
Have antagonistic properties at D2, H1 and M1 sites
Commonly used as first line agents
Oral, rectal or IV
Prochlorperazine (Compazine)
Promethazine (Phenergan)

Question 2

Main adverse effects of the phenothiazines

Answer 2

Extrapyramidal reactions such as dystonia
Compazine has higher incidence of EPS than Phenergan (treated with diphenhydramine 25 to 50 mg IV or IM)
Hypotension can also occur, particularly in the elderly or with intravenous infusion

Question 3

Serotonin 5-HT3 Antagonists Clinical Uses

Answer 3

Ondansetron (Zofran)
Great for postoperative and chemotherapy induced nausea and vomiting
Can be used for most cases of nausea and vomiting except not great for nausea secondary vertigo
Usually effective as single agents

Question 4

Antibiotics for Treatment of Infectious Diarrhea

Answer 4

Oral Fluoroquinolone: Ciprofloxacin for 3-5 days

or Flagyl for ghiarrdia, parasitic etc.

Question 5

First line pharmacotherapy for the treatment of constipation

Answer 5

Bulk forming agents: Psyllium (Metamucil)
Ducosate derivatives: Ducosate sodium (Colace)
Glycerin: Suppository – most often used for infants

Question 6

Bulk forming agents Contraindications

Answer 6

Esophageal strictures
GI ulcerations
Strictures anywhere along the GI tract

Celiac patients need a specific gluten free formulation

CAUTION in DM: some contain up to 20 g carbohydrates per serving (Metamucil has a sugar free formula)

Don’t take with tetracyclines

Question 7

Polyethylene glycol electrolyte solution (Golytely)

Answer 7

Powerful osmotic laxative
Used for bowel prep for endoscopic procedures
Side effects:
Sleep disorder, rigors, malaise
Increased thirst, abdominal distention and pain
Anorectal pain, bloating, nausea