Lecture 17A: GI Drugs

Famotidine (Pepcid)

MOA: H2 receptor antagonist

Indication: Dyspepsia, PUD, GERD

SE:

• PUD: single daily dose at bedtime

• GERD: using step-up therapy, can increase to BID

Omeprazole (Prilosec)

MOA: Proton pump inhibitor (inhibits H+, K+-ATPase) in luminal membrane of gastric parietal cells

Indication: Dyspepsia, PUD, GERD

SE:

• Low magnesium

• High dose PPI’s can cause CKD and can be associated with increased risk of osteoporosis

Calcium carbonate (Tums)

MOA: Gastric antacid

Indication: Dyspepsia/GERD

SE:

• Constipation

• Rebound acid secretion in large doses

Hydrocortisone (Cortef)

MOA: Glucocorticoid

Indication: Ulcerative colitis, Crohn’s disease

SE:

• Can be administered as rectal enema

• Common side effects of steroids

Mesalamine (Asacol/Lialda)

MOA: Metabolite of sulfasalazine; exerts anti-inflammatory effects by inhibiting prostaglandin synthesis
Indication: Ulcerative colitis, Crohn’s disease

Metoclopramide (Reglan)

MOA: Prokinetic drug that increases GI motility by blocking Dopamine D2 receptors

Indication: GERD, diabetic gastroparesis, and intractable hiccups

SE: Also exerts antiemetic effect by blocking Dopamine D2 and Serotonin 5-HT3 receptors in the chemoreceptor trigger zone

Polyethylene glycol (Miralax)

MOA: Osmotic laxative; retain water in intestinal lumen and increase intraluminal pressure, stimulating peristalsis

Indication: Constipation

SE:

• electrolyte abnormalities

• avoid giving sodium phosphate in patients with renal impairment

Psyllium (Metamucil)

MOA: Bulk-forming laxatives; absorb and retain water in the intestinal lumen

Indication: Constipation

SE: Rarely cause adverse effects

Docusate (Colace)

MOA: Surfactant laxative (stool softeners)

Indication: Constipation

SE: Soften stool, but minimal evidence that causes increase in gut motility

Linaclotide (Linzess)

MOA: Causes increased secretion of chloride and bicarbonate into
the intestines, leading to increased intestinal fluid accumulation and motility

Indication:

• Chronic idiopathic constipation (CIC)

• IBS-C (constipation predominant)

SE: Diarrhea

Sennakote (Senna)

MOA: Stimulant laxative; acts directly on intestinal mucosa to
stimulate peristalsis

Indication: Constipation

SE: abdominal pain; cramping

Loperamide (Imodium)

MOA: Opioid agonist in gastrointestinal smooth muscle

Indication: Diarrhea

Ondansetron (Zofran)

MOA: 5HT-3 antagonist

Indication: nausea, vomiting

• Often used in chemotherapy-induced nausea

SE:

• Higher levels are associated with increase in QTc

Dronabinol (Marinol)

MOA: Oral formulation of THC

Indication: Cancer chemotherapy-induced emesis

SE: Also used an appetite stimulant