11 - GI Disorders Flashcards by Anna Van Dekerkhove

Gastric mucosa is secreted from ______

Mucosal epithelial cells

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What is the function of the mucous layer in the gut?

Protects cells from acid and enzymes

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What happens if the mucous layer of the stomach is lost?

It will allow acid to reach the cells and cause an ulcer

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What is the primary role of stomach acid?

Kill bacteria, viruses and other parasites (not for digestion)

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What can overproduction of stomach acid cause?

Ulcers

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How long are antacids recommended to be used for?

Very short term (1 day)

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What is a systemic antacid that is used?

NaHCO3 (sodium bicarbonate)

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What is the mechanism of sodium bicarbonate as an antacid?

Dissociates into Na+ and HCO3-

- Bicarbonate ion absorbed into the blood and slightly increases pH

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What are advantages to bicarbonate antacids?

Quick and easy

- Effective in short term to reduce stomach acid

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What are problems w/ bicarbonate antacids?

Alkalotic urine can increase deposition of calcium and phosphate to form a kidney stone
Increases blood sodium, thus exacerbating hypertension
Acid rebound due to feedback regulation

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What are some non-systemic antacids?

Calcium carbonate
Aluminum hydroxide
Magnesium hydroxide

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What is important to note about non-systemic antacids?

Do not effect extracellular or blood pH

- Aluminum and calcium are constipating, so are often combined w/ magnesium

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What is the mechanism of anticholinergics for GI ulcers?

Muscarinic ACh receptors in parietal cells stimulate HCl secretion
Inhibition of these receptors reduces acid secretion

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What are side effects of anticholinergics?

Dry mouth
Vision problems
Sedation

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What are cytoprotective drugs? What are the 2 major examples?

Drugs that protect cells from acidic damage, either directly or through stimulation of mucous
Sucralfate and misoprostol

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What is the function of sucralfate?

Binds to H+ ions to form a gooey paste, increasing pH
Binds to degenerating cells, forming a protective layer
“Artificial” mucous

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What is important to note about sucralfate?

Not absorbed into bloodstream, but can inhibit absorption of other drugs
Works for 8-12 hours

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What is the action of misoprostol for GI ulcers?

Prostaglandin analogue, so stimulates production of mucosal barrier

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What is the action of H2 blockers for GI ulcers?

Stimulation of H2 receptors in parietal cells increases HCl production

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Do H2 blockers cause any adverse effects?

No b/c very specific to organ and the receptor type

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What are examples of H2 blockers?

Cimetidine
Ranitidine
Famotidine

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Rank from least to most effective: ranitidine, famotidine, cimetidine

Cimetidine < ranitidine < famotidine

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What are the ingredients of Pepcid AC?

Pepcid = famotidine = H2 blocker

- AC = antacid

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What are side effects of PPI’s?

Osteoporosis

- Increased risk of stroke

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What are the actions of proton pump inhibitors?

- Inhibit gastric H+/K+ ATPase | - Binds to H+ extrusion sites, and block release of H+ and Cl-

What are PPI's especially good for?

- Rapid reduction of acid | - GERD and other acid-dependent disorders

What are the 2 most common PPI's?

- Omeprazole | - Esomeprazole

Are PPI's given as pro-drugs?

Yes, converted to active drug in the secretory canaliculus of the parietal cell

What is the mechanism of H. pylori to cause ulcers?

- Burrows in gastric mucosa to escape gastric acid - Produces urease (enzyme that converts urea to ammonia and CO2) - Urease kills mucosal epithelial cells, leaving the gut unprotected

What can be done to test for an H. pylori infection?

- Breath test for urea - Serological - Culture - Histology

What is the recommended tx for H. pylori infection?

- Triple therapy = PPI to control acid and 2 effective antibiotics to kill H. pylori - Quadruple therapy = add bismuth

___ is the most prevalent type of ulceration

GERD

Which drugs reduce LES pressure?

- Beta blockers - Ca channel blockers - Nicotine

What is the most effective tx for GERD?

- Behaviour change - Avoid fat, caffeine, chocolate peppermint, and alcohol - Avoid large meals and stop smoking

What is ulcerative colitis?

- Inflammation of submucosa | - Ulcerations may cover entire surface of colon

What does ulcerative colitis cause?

- Diarrhea - Bleeding - Severe pain

What is Crohn's disease?

- Inflammatory disease which can cover entire digestive system - Tends to be separate, isolated regions - Fistulas may form and intestinal wall may be breached - May also be associated w/ severe skin inflammation

Does IBD have a cure?

No, only treatments which are variably effective

Which condition will be eliminated w/ surgical removal of the colon?

Ulcerative colitis

What is the first-line tx for mild to moderate ulcerative colitis?

5-amino salicylic acid (mesalamine)

What is the MOA of 5-ASA?

Unknown

What is significant about sulfasalazine?

5-ASA linked to sulfapyridine, and the 5-ASA is only released in the large intestine by bacteria

What are 3 possible responses px can have to glucocorticoids?

- Steroid responsive = sx improve over 1-2 weeks and disease remains in remission as steroids are tapered off - Steroid dependent = px respond to steroids but experience relapse of the disease w/ tapering of the steroids - Steroid unresponsive = px do not respond to steroid tx

When are glucocorticoids used for ulcerative colitis?

Moderate to severe cases

What are the side effects of glucocorticoids?

- Weight gain, stress, and emotional responses - Steroid-dependent diabetes - Increased risk of infection

When are immunosuppressants used for UC and Crohn's?

Only used for Crohn's that are unresponsive to prednisone and TNF alpha inhibitors (if UC is unresponsive to these drugs, recommend colon removal)

Which immunosuppressants are thiopurine derivatives?

- Mercaptopurine | - Azothiopurine

When are thiopurines used?

- For steroid-resistant or dependent px | - Useful in remission and reduction of relapse of UC and Crohn's

What is a side effect of thiopurines?

Small risk of major infection, esp. in co-tx w/ steroids

What is methotrexate? When is it used?

- Dihydrofolate reductase inhibitor (blocks DNA synthesis) | - Reserved for steroid resistant or dependent px

When is cyclosporine used?

Only for severe Crohn's cases

What is cyclosporine?

Calcineurin inhibitor

When are TNF alpha inhibitors indicated?

2nd line when px not responsive to prednisone

Which drug is a TNF alpha inhibitor that is effective as a UC tx?

Infliximab

What is a side effect of TNF alpha inhibitors?

Increased chance of serious lung infection

What is the difference between prebiotics and probiotics?

- Prebiotics = food that helps good bacteria grow | - Probiotics = drug that actually contains bacteria

What is the simple tx for diarrhea?

- Clear liquids | - BRAT diet (banana, rice, apple sauce, tea)

What can be used for diarrhea that isn't caused by an infectious agent?

Opiates or opiate-related agents b/c they decrease intestinal motility

What are side effects of opiates?

- CNS depression | - Constipation

Which opiates are used for diarrhea?

Tincture of opium, paregoric, and/or codeine

Which opiate-related agents are used for diarrhea?

- Diphenoxylate | - Ioperamide

What do adsorbents do? What are examples?

- Coat the wall of the GI tract and adsorb bacteria or toxins causing diarrhea - Ex: kaopectate and pepto-bismol