GI Disorders Flashcards by Sara Sverker

What receptors are in the vomiting center?

H1
M1
5HT3
NK1

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What emesis receptors are in the chemotrigger zone (CTZ)?

D2
5HT3
NK1
CB1

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What emesis receptors are in the vestibular system and what does activation of these cause?

H1
M1

Motion sickness

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What receptors are in the GI tract that can also modulate emesis?

Smell; rotten food

Mu
5HT3
D2
CB1/2
NK1

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What does agonizing the corpus striatum D1 and D2 receptors do?

Control of movement and posture

Treats Parkinson’s disease

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What does agonizing the limbic systems D1, D2, D3, and D4 receptors do?

Causes aggression, agitation, hallucinations, and hypervigilance

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What does agonizing the pituitary glands D2 receptors do?

Increases GH release and decreases prolactin release causing decreased breast milk and treatment of amenorrhea

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What does antagonizing the corpus striatum D1 and D2 receptors do?

Slowed and abnormal movements

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What does antagonizing the limbic systems D1, D2, D3, and D4 receptors do?

Reduces aggression, agitation, and vigilance = Antipsychotics

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What does antagonizing the Pituitary glands D2 receptors do?

Increases prolaction release

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Where is are the target receptors of D2 receptor antagonists in order to treat vomiting?

CTZ D2 receptors

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Are D2 receptor antagonists selective to their target receptors?

No, they will also antagonize other D2 receptors throughout the body and will cause ADRs

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What are the ADRs of D2 Receptor antagonists?

Movement disorders
Prolactin release
Sedation
Hypotension

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What other receptors does D2 receptor antagonists act on?

GIT = improving GI motility and LES

block H1 receptors to treat motion sickness

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What are the effects of 5HT3 Receptor antagonists?

The target receptors are found in the GI tract

Antagonism reduces vomiting

Most effective to treat CINV

Not effective against motion sickness

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What is Metoclopramide?

D2 and 5HT3 receptor antagonist

Less effective than agents for the individual receptors

Has prokinetic effect and can be used to treat GERD by causing the stomach acid to keep moving and not sit in the LES

4X/day dosing

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What is Aprepitant/Fosaprepitant?

Neurokinin-1 Receptor antagonist

Workson substance P receptors found in CTZ and GIT

No analgesic effect; only used to prevent CINV

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What are the ADRs for Metoclopramide?

BBW for tardive dyskinesia

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What are cannabinoid Receptor Agonists?

Act on CB1 receptor in CTZ and CB1/2 receptors in periphery

Used for CINV, anorexia, and AIDs related wasting

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What are the ADRs of cannabinoid receptor agonists?

Tachycardia
Palpitations
Euphoria
Altered sense of reality
Xerostomia
Hunger

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What can occur in withdrawal of cannabinoid receptor agonist?

Insomnia

Irritability

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What drugs do we use to treat constipation?

Stimulant laxative and stool softener

What are the treatments used to treat diarrhea?

Bismuth Subsalicylate
Peripheral Mu-agonists
Bile acid sequestrants in refractory cases

What are the side effects of Bismuth subsalicylate?

Salicylate toxicity

Darkened stool and tongue

How is acid produced in the stomach?

Parietal cells make acid (H) after ACh, histamine, and/or gastrin receptors are activated Acid is secreted out of the parietal cells by H/K Proton pumps into gastric lumen

What causes acid production in the stomach to turn off?

Somatostatin which causes less gastrin release/activation

What disease states involve acid production in the stomach?

Peptic Ulcer Disease (PUD) Gastro-esophageal Reflux disease (GERD) Stress ulcer prophylaxis

What are the underlying causes of PUD?

``` H. pylori NSAID Smoking Liver cirrhosis Stress ```

What are the goals of treatment for PUD?

Reduce symptoms | Heal lesions

What are the approaches to treating PUD?

Get rid of any offending agent = if H. Pylori, patient must be treated with antibiotics for 10-14 days first Protect stomach lining Reduce/neutralize acid production

What drugs will Protect the stomach lining?

Misoprostol | Sucralfate

What drugs will reduce/neutralize acid production?

H2RAs | PPIs

What is Misoprostol?

Prostaglandin E analog Increases mucus production and is a cytoprotective Used in ulcer treatment/prophylaxis from NSAID use; Promotes labor and induces cervical ripening

What is a cytoprotective agent?

Works really good at treating the ulcers but doesn't have any acid issues

What are the ADRs of Misoprostol?

DIARRHEA Uterine contractions (abortification)

What is Sucralfate?

Aluminum sucrose sulfate that is activated in the presence of stomach acid This drug forms a viscous adhesive coating over an ulcer by binding charged proteins in the ulcer

What are the ADRs of Sucralfate?

Constipation Many DDIs Accumulates in renal insufficiency

What are Histamine 2 Receptor Antagonists (H2RAs)?

-Tidines Reversible binding of receptors Have potential for tolerance to build up Reduce nocturnal and post-prandial acid secretion Must be renally dose adjusted Fairly well tolerated

What are PPIs?

-prazole Irreversibly inhibit H+/K+ ATPase pump Has delayed onset because it requires activation by acid in parietal cells (its a prodrug) = NOT for immediate symptom release

What are ADRs of PPIs?

``` Rebound acidity upon d/c (taper with chronic use) Osteoporosis/fractures C. diff Low Mg/B12 Pneumonia Dementia CKD CAD Death ```

What is GERD?

Occurs when the amount of gastric juice that refluxes into the esophagus exceeds the normal limit, causing symptoms with or without associated esophageal mucosal injury

What are the goals of GERD treatment?

Reduce symptoms | Heal esophagitis

What are the symptoms of GERD?

heartburn (pyrosis) Regurgitation Dysphagia

What are the therapeutic approaches to GERD?

Inhibit retrograde movement = improve LES function/tone; Prokinetic action Reduce/neutralize acid production = Get rid of any offending agent/consider lifestyle modifications

What drugs are used to treat GERD?

all the same ones as PUD Also includes Antacids

What are antacids?

Neutralize acid and raise gastric pH Calcium, Magnesium, and Aluminum Used for intermittent symptomatic relief because of rapid onset and short duration

What are ADRs of antacids?

Constipation (Ca/Al) Diarrhea (Mg) Accumulation of Mg/Al in renal insufficiency

What are the DDIs of antacids?

Chelation (fluoroquinolones, tetracyclines, and levothyroxine) Reduced absorption caused by increases in pH = azole antifungals, bisphosphonates, iron

What should you avoid using H2RAs with?

Cimetidine

What are the clinical pearls of H2RAs?

Can be taken with or without foodL Heartburn/GERD = take 30-60 min. before food PUD course = 4-8 weeks Inexpensive Less effective than PPIs for erosive esophagitis DDIs with pH dependent absorption

What are the PPI clinical pearls?

Commonly overprescribed and unnecessarily continued Different course for different disease: Heartburn = 2 weeks GERD = 4 weeks PUD = 4-8 weeks Need to be taken 30-60 minutes before a meal for symptomatic heartburn Not for as needed use DDI's with pH dependent absorption

Which two PPIs do not need to be taken 30-60 minutes before a meal?

Rabeprazole | Dexlansoprazole

OMeprazole and Esomepazole have DDI's with what?

Moderate 2C19 inhibitors like clopidogrel