GI Meds Flashcards
Guanylate Cyclase-C (GC-C) Agonists
● Linaclotide (Linzess)
● Plecanatide (Trulance)
Chloride Channel activator
Lubiprostone (Amitiza)
What is OIC?
Opioid Induced Constipation:
● Chronic opioid use is very common in US medicine. (Opioid Epidemic)
● Opioids cause decreased motility and decrease peristalsis.
● Potential for constipation and ileus.
Management of OIC?
● Prophylactic laxative or stool softener
● Increase fluid intake
Peripherally-Acting Opioid Antagonists
● Naloxegol (Movantik)
● Methylnaltrexone (Relistor)
● Naldemedine (Symproic)
Peripherally-Acting Opioid Antagonists indication/MOA
Blocks action at the mu receptor
Indication: Opioid-induced constipation
Black Box Warnings of Guanylate Cyclase-C (GC-C) Agonists
Risk of serious dehydration in pediatric patients younger than 2 years
Antiemetics include:
Anticholinergic Agents:
Dopamine Receptor Antagonists:
● Phenothiazines: Promethazine (Phenergan),
Prochlorperazine (Compazine)
● Benzamide: Metoclopramide (Reglan)
5-HT3 Receptor Antagonists:
Antacids and Acid Reducers:
PPIs
Histamine 2 receptor agonists
Antacids/alkalinizing agents
Mucosal Protective Agents
Anti-Diarrheals (Antimotility) Agents
Laxatives include
Bulk-Forming Laxatives
Osmotic Laxatives
Stimulant Laxatives
Lubricant Laxative
Stool Softener (Surfactant)
Guanylate Cyclase-C (GC-C) Agonists
Peripheral acting Opioid receptor antagonists
Chloride Channel Activator
Anticholinergic Agent
Scopolamine
Scopolamines form of medication
72- hour transdermal patch
D2 Receptor Antagonists - Phenothiazines MOA
● Promethazine (Phenergan)
● Prochlorperazine (Compazine)
Selectively antagonize the
Dopamine D2 receptors centrally
BOX WARNINGS for D2 Receptor Antagonists - Phenothiazines
○ Promethazine - severe respiratory depression and death in Pts under 2.
○ Promethazine - severe tissue injury and gangrene with injectable form.
○ Prochlorperazine - not be used in patients with dementia-related psychosis.
Anticholinergic Side effects
Hot as hell
Blind as a bat
Dry as as bone
Red as a beet
Mad as a hatter
Stuffed as a pipe
Side Effects of Phenothiazines
Significant drowsiness, sedation, extrapyramidal symptoms (dystonia, Parkinson’s symptoms), hypotension
D2 Receptor Antagonists - Benzamides MOA
○ Increases gastric motility by blocking
intestinal Dopamine receptors.
○ Increases LES tone and stimulates
contractions, thereby increasing GI
motility and decreasing the sensation
of nausea.
Contraindications of D2 Receptor Antagonists - Benzamides
Confirmed or suspected bowel obstruction, perforation, or hemorrhage
Hyperprolactinemia can occur as a side effect of ____
D2 Receptor Antagonists - Benzamides
(Dopamine inhibits prolactin release)
Box Warning of D2 Receptor Antagonists - Benzamides
can potentially cause Tardive Dyskinesia, which is often
irreversible. Risk increases with longer duration of treatment and
higher total cumulative dose
5-HT3 Receptor Antagonists
● Ondansetron (Zofran)
● Granisetron
5-HT3 Receptor Antagonists MOA
○ Act as anti-nausea medication by
blocking Serotonin (5-HT3) receptors
on afferent nerves in the gut.
For which medication are we concerned about QT prolongation as an adverse effect?
5-HT3 Receptor Antagonists
Odansetron (Zofran)
Proton Pump Inhibitors (PPIs) MOA
○ Block gastric acid secretion and decrease
intragastric H+.
○ Done by inhibiting hydrogen-potassium
ATPase pump on the luminal surface of
parietal cells
Maximum acid inhibition for PPIs is reached after ____ days of use.
3-4
Histamine 2 Receptor Antagonists
● Famotidine (Pepcid, Zantac 360)
● Cimetidine (Tagamet)
● Nizatidine (Axid)
Histamine 2 Receptor Antagonists MOA
Blocks Histamine 2 receptors on parietal
cells, preventing histamine-induced acid
secretion.
■ Decreases gastric acidity
Long term Cimetidine has been associated with _____
Gynecomastia.
Antacid (Alkalinizing) Agents
● Calcium Carbonate (Tums)
● Sodium Bicarbonate
(Alka-Seltzer)
● Magnesium and Aluminum
Hydroxide (Maalox brand
discontinued, Mylanta)
Antacid (Alkalinizing) Agents MOA
○ These are all considered “buffers”
and interact with H+ in the gastric
lumen, neutralizing the acid,
raising the pH.
Calcium carbonate- Should not be taken if _____
frequent kidney stones or in
patients with hypercalcemia
Mucosal Protective Agents
Sucralfate (Carafate)
Misoprostol (Cytotec)
Sucralfate (Carafate) MOA and Indications
○ Acts primarily by forming a physical barrier
over the injured epithelium and also
increasing the secretion of mucous.
Indications -
○ Duodenal Ulcers
○ GERD in pregnancy
Misoprostol (Cytotec) MOA
Mechanism of Action: A prostaglandin analogue, which stimulates mucous
production and weakly inhibits the proton pump.
Misoprostol (Cytotec) Indications
○ Peptic Ulcer Disease
○ Prevention of NSAIDs induced gastric ulcers.
○ Cervical Ripening and Labor Induction (Given vaginally).
○ Medical termination of pregnancy before 70 days
Misoprostol (Cytotec) BBW
Contraindicated during pregnancy (other than for induction) because it may cause birth defects, abortion, or premature birth (BBW)
○ Do not use in a female patient within childbearing age, unless you ensure
they are not pregnancy and are on birth control (BBW)
Bismuth Subsalicylate MOA
○ Antisecretory, antimicrobial, and antiinflammatory action.
○ Reduces irritation of stomach and intestinal lining through
inhibition of prostaglandin
Bismuth Subsalicylate contraindications
Children with a recent history of viral infection. It is converted to salicylic acid (like Aspirin) and increases risk of Reye’s Syndrome.
Opiate Receptor Agonists
● Loperamide (Imodium)
● Diphenoxylate + Atropine (Lomotil
Opiate Receptor Agonists MOA
These bind to opioid receptors in the bowel and lead to decreased bowel peristalsis (↓ propulsion) and
decreased secretions (↓ motility). This equals increased intestinal transit time and harder stool.
Loperamide Indications
Mild/moderate, acute, non-febrile, non-bloody diarrhea
■ Chronic diarrhea associated with Irritable Bowel Syndrome.
Opiate Receptor Agonists contraindications
○ Some forms of significant infectious diarrhea
○ Contraindicated in diarrhea secondary to Inflammatory Bowel Disease.
Loperamide BBW
potential to cause Torsades
and sudden cardiac death if taken at too high of a dose.
Stool Softener
Docusate Sodium (Colace)
Docusate Sodium (Colace) MOA
○ Reduces surface tension of the
oil-water interface of the stool resulting
in enhanced incorporation of water and
fat, leading to softer feces.
Bulk-Forming Laxatives (Fiber)
● Psyllium (Metamucil)
● Methylcellulose (Citrucel)
● Polycarbophil (FiberCon)
● Wheat dextrin (Benefiber)
Bulk-Forming Laxatives (Fiber) MOA
● These are polysaccharides or cellulose
derivatives that resist digestion and retain
water
● Fiber promotes intestinal motility by increasing the bulk of the stool.
● The result is increased frequency of stooling and softer consistency
of stool.
Osmotic Laxatives
● Sodium Phosphate (Fleet Enema)
● Lactulose (a synthetic disaccharides)
● Polyethylene Glycol (MiraLax,
GoLytely)
● Glycerin (can be suppository)
Saline-type osmotic laxatives:
● Magnesium Hydroxide (Milk of
Magnesia)
● Magnesium Sulfate (Epsom Salt)
● Magnesium Citrate
Osmotic Laxatives MOA
● These increase the luminal osmolality,
creating an inward osmotic force,
pulling water from the vasculature
into the lumen of the intestines.
______ is the safest and most gentle Osmotic Laxative.
Polyethylene Glycol
Stimulant Laxatives
● Senna (Ex-Lax)
○ “Sennosides”
● Bisacodyl (Dulcolax)
Stimulant Laxatives MOA
○ Also known as “irritant laxatives,” these
work by irritating the intestinal wall, which
leads to an accumulation of fluid and
electrolytes, which increases motility and
produces a bowel movement.
