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41 Cards in this Set
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63 yo he is bloated after eating with nausea that can keep him up at night. He is prescribed a low dose of metoclopramide because it will most likely:
1) block D2 receptors and help him sleep 2)Activate 5-HT4 receptors and increase gut motility 3)Block 5-HT3 receptors and reduce his nausea |
2)Activate 5-HT4 receptors and increase gut motlitiy
this is treating diabetic gastroparesis |
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gut motility effect of metoclopramide
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block D2, activate 5-HT4
at low dose |
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emesis effect of metoclopramide
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Block D2 (low dose) block 5-HT3
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What cells secrete gastric acid?
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Parietal cells
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What is the body’s natural defense against gastric acid?
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mucus and bicarb
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What stimulates HCI secretion by parietal cells? 3
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Gastrin
ACh Histamine |
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What can you do to prevent HCI release from parietal cells? 3 (general mech)
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block M cells
block H2 receptors ATPase blocker (greatest prevention of acid release) |
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What is the problem with using muscarinic blockers for the treatment of ulcers?
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side effects
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how do you get the production of a mucus layer?
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Prostaglandin binds to EP3 receptor which leads to production of mucus and HCO3
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what do prostaglandins do in the stomach aside from making the bicarb/mucus layer
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coupled to Gi--> decrease cAMP--> decreases gastric acid release from parietal cells
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What can you do to help treat a gastric ulcer? (select all that apply)
Increase gastric mucous production Cover up the ulcer Reduce gastric acid production Tighten the LES Stop taking aspirin Eradicate H. Pylori Neutralize gastric acid |
Increase gastric mucous production
Cover up the ulcer Reduce gastric acid production Eradicate H. Pylori Neutralize gastric acid aspirin is dependent on the situation |
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What can you do to help treat GERD? (select all that apply)
Increase gastric mucous production Reduce gastric acid production Tighten the LES Eradicate H. Pylori Increase gastric motility Neutralize gastric acid |
Reduce gastric acid production
Tighten the LES Increase gastric motility Neutralize gastric acid |
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drugs that end in -prazole are what kind of drugs?
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Proton Pump Inhibitors
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Omeprazole (Prilosec, Zegerid)
Esomeprazole (Nexium) Lansoprazole (Prevacid) Dexlansoprazole (Dexilant) Rabeprazole (AcipHex) Pantoprazole (Protonix) what kind of drugs? |
Proton Pump Inhibitors
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Zegerid is immediate releast omeprazole + ____?
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+ sodium bicarb
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What would happen to omeprazole if it was not enteric coated?
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destroyed by acid environment of the stomach
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PPI’s are weak bases
pKa of omeprazole is 4 What does this mean in blood (pH 7.4) and in canalicular space (pH 0.8)?? |
in blood: uncharged
in canalicular space: charged |
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MOA of omeprazole?
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The proton pump inhibitors are absorbed in the small intestine.
They are brought to the parietal cells via the systemic circulation. They are activated in the acid environment of the gastric parietal cell secretory canaliculi. The active metabolites bind covalently to the H+-K+-ATPase thereby irreversibly inhibiting acid release. note: only the charged drug does this |
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PPIs are usually taken 0.5-1 hour before meals.
Why? |
Eating stimulates pump activity and acid production
Acid is required for activation of the drug. The pumps need to be active at the wall of the canalicular space to bind PPIs. |
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Why is the duration of action not directly related to the plasma half life for PPIs?
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Irreversible inhibition of the proton pump...so you have to make more proton pumps
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Major clinical uses of Proton Pump Inhibitors
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Gastric/duodenal ulcers
GERD |
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important side effect of proton pump inhibitor? 2
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Increased risk of pneumonia and possibly some other infections
increased risk of fractures due to reduced calcium absorption (acid is needed to absorb calcium carbonate) (so look out for post menopasual women) |
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what drug can you NOT give with PPIs?
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Clopidigrel
this is because omeprazole (PPI) blocks CYP2C19, which is responsible for making the active metabolite for clopidogrel |
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Cimetidine (Tagamet)
Ranitidine (Zantac) Famotidine (Pepcid) Nizatidine (Axid) are what kind of drugs? |
H2 blockers
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drugs ending in -tidine do what?
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H2 blockers
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what dosage of H2 blockers do you need to give high/low for prevention of NSAID induced ulcers?
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HIGH
(these aren't as affective as PPI) |
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adverse effects of Cimetidine?
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Gynecomastia – men
Galactorrhea - women (remember this is a H2 blocker) |
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what type of drug is Misoprostol
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Synthetic analog of prostaglandin E1
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MOA of misoprostol?
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Activates prostaglandin receptors (EP) on epithelial cells thereby increasing mucous and bicarbonate secretion.
Activates prostaglandin receptors (EP3) on parietal cells. This activates Gi, which inhibits the production of adenylyl cyclase thereby decreasing the activity of the proton pump and decreasing acid secretion. Does more with reducing ACID production (as opposed to making a mucin layer) |
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What enzyme do they inhibit that is involved in prostaglandin synthesis in the gut?
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COX-1
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big use of misoprostol?
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Prevention of mucosal injury caused by NSAIDs
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adverse side effects of misoprostol?
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Diarrhea with or without abdominal pain
due to increased smooth muscle contraction |
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2 pts that are contraindicated for misoprostol?
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IBS (makes diarrhea worse)
Pregnancy (Cause abortion by increasing uterine contractility) note: use is Prevention of mucosal injury caused by NSAIDs |
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Sucralfate is a drug that does what?
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At low pH (<4) it cross-links and forms a gel-like substance that adheres to epithelial cells and ulcers
Lasts for as long as 6 hours This protects ulcerated tissue from acid, pepsin and bile salts covers up the ulcer |
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Should you take an antacid prior to taking sucralfate?
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NO
need low pH |
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clinical uses of sucralfate?
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Duodenal and gastric ulcers
(remember this was the gel patch for ulcers) |
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side effect of sucralfate?
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CONSTIPATION
releases aluminum Remember: this was the gel used to cover gastric/duodenal ulcers...needs low pH to be activated |
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MOA for Bismuth Subsalicylate (Pepto)
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Binds to mucosal glycoproteins
Coats the crater Binds pepsin Direct antimicrobial activity against H pylori |
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clinical use for Bismuth Subsalicylate (Pepto)
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Gastric and duodenal ulcers
In combination with antibiotics for eradication of H. pylori |
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side effects of bismuth subsalicyclate?
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Darken stool and tongue
remember: this was used to kill h. pylori as well as coat the ulcers (not to be confused with sucralfate, this is PEPTO!) |
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What is the major problem with antibiotic use?
so what do you do? |
Resistance
must give triple therapy (2 antibiotics and a PPI) |
