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115 Cards in this Set
- Front
- Back
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Three types of agents that suppress acid production
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1. Proton pump inhibitor
2. H2 receptor antagonist 3. Misoprostol |
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What cells in the stomach secrete acid?
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Parietal cells
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What two things do parietal cells secrete?
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Acid
Intrinsic Factor |
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Neuronal regulation of gastric acid secretion is mediated by what neurotransmitter and binds to which receptor?
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Ach:M3 receptor
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Endocrine regulation of gastric acid production is regulated by what two hormones?
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Gastrin and CCK2
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What do enterochrommaffin cells secrete?
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Histamine
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What do G cells secrete?
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Gastrin
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What do D cells secrete?
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Somatostatin
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What is the function of somatostatin?
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Inhibit gastric acid secretion
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Paracrine regulation of gastric acid secretion includes what mediator and binds to which receptor?
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Histamine:H2 receptor
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What is the function of the LES?
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Revent gastric reflux
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What is the function of the mucus layer in the stomach?
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Prevent mucosal damage
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What stimulates the production of gastric mucus?
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Prostaglandins
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What is the function of bicarbonate secretion?
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Acid neutralization
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Where does the proton pump inhibitor act?
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H+/K+ ATPase in the parietal cell membrane
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What receptor does PGE2 and PGI2 bind to?
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EP3 receptor
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Where is the M3 receptor located and what binds to it?
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ECL cell and binds Ach
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What is the only PPI available OTC?
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Omeprazole (prilosec OTC)
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Name four PPI's (available Rx)
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Esomeprazole
Lansoprazole Rabeprazole Pantoprazole |
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What is esmeprazole?
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PPI
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What is Lansoprazole?
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PPI
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What is Rabeprazole?
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PPI
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What is Pantoprazole?
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PPI
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What drug is used to promote healing of gastric ulcers?
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PPI (omeprazole, esomeprazole, lansoprazole, rabeprazole, pantoprazole)
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What drug is used to treat GERD?
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PPI (omeprazole, esomeprazole, lansoprazole, rabeprazole, pantoprazole)
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What drug is used to treat Zollinger-Ellison syndrome?
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PPI (omeprazole, esomeprazole, lansoprazole, pantoprazole, rabeprazole)
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What is Zollinger-Ellison syndrome?
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Gastrin overproduction leading to over production of acid
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What drug is used to reduce the risk of duodenal ulcer recurrence associated with H. pylori?
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PPI (omeprazole, esomeprazole, lansoprazole, pantoprazole, rabeprazole)
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PPI's exist as active drugs or prodrugs?
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PPIs exist as prodrugs
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PPI's bind reversibly or irreversibly with -SH groups?
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Irreversibly bind
Therefore require resynthesis of pump to restore acid secretion |
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Where does trapping of PPI's occur?
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Parietal cell canaliculi
Where acid is being produced, then activates the drug and it forms a covalent bond with the sulfate (cysteine) -SH group |
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PPI's must be available in enteric coated delayed release dosages, why?
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So it wont get broken down in stomach acid. Must bypass.
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Elimination T1/2 of PPI = 1-2 hours, but duration of action is 24-48 hours, why?
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Because activated PPIs bind irreversibly to the cysteine -SH group
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How are PPI's metabolized?
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Hepatic metabolism (CYP2C19 and CYP3A4)
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Those who are poor metabolizers of PPIs because they have a variant of CYP2C19 are at risk of what?
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Toxicity
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Does hepatic disease reduce clearance of PPIs?
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Yes
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Does renal disease reduce clearance of PPIs?
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No
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What dose adjustment is recommended in patients with hepatic disease?
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Dosage reduction of PPIs
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Should you or should you not administer PPIs with acid suppressing medications?
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Should not administer PPIs with acid suppressing medication
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To achieve maximum suppression of acid secretion, just one dose or several doses?
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Several doses
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Are all proton pumps active at the same time?
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No they are not.
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Name 4 H2 receptor antagonist
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1. Cimetidine
2. Ranitidine 3. Famotidine 4. Nizatidine |
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H2 receptor antagonists (cimetidine, ranitidine, famotidine, nizatidine) reversibly or irreversibly compete for histamine?
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Reversibly compete for histamine
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Histamine:H2 activates or inhibits the cAMP dependent pathway?
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inhibits cAMP dependent pathway
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Activation of cAMP dependent pathway in the stomach leads to activation or inhibition of the H/K ATPase pump?
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Activation of H/K ATPase (proton pump)
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When are H2 receptor antagonists most effective (time of day?)
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At night time (Nocturnal acid secretion)
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Gynecomastia and impotence in males can occur with which H2 receptor antagonist?
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Cimetidine
Displaces DHT from binding sites, and prevents P450 metabolism of estrogen |
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Why are there more side effects with cimetidine versus other H2 receptor antagonists (ranitidine, famotidine, nizatidine?)
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Cimetidine causes greatest inhibition of CYP450
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Which of the H2 receptor antagonists have virtually no inhibition of CYP450?
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Famotidine
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What is ECL cell?
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Enterochromaffin like cell
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Tolerance is a problem with H2 receptor antagonist. Why is it not a problem with PPIs?
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PPI action is downstream of histamine action
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Why should terminal dosage of H2 receptor antagonists and PPIs be tapered?
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Acid rebound: increase in gastric acidity when drug use is discontinued
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Misoprostol
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Prostaglandin analog
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Prostaglandins activate/inhibit the cAMP pathway?
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Inhibit the cAMP pathway (cAMP activates H/K ATPase proton pump)
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What receptor does misoprostol bind?
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EP3 on parietal cells
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What is the main action of misoprostol?
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Inhibit acid secretion
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What is a secondary action of misoprostol?
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Stimulate secretion of mucin and bicarbonate (cytoprotective)
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Which drug also has cytoprotective actions?
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Misoprostol (PG analog)
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Which drug is currently approved by FDA for prevention of mucosal injury induced by NSAIDS
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Misoprostol
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Salcralfate
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Sulfated polysaccharide with Al(OH)3
X-linking in acid pH 4 produces viscous sticky polymer that adheres to epithelial cells and ulcer craters |
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Name 4 Antacids:
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1. Sodium bicarbonate
2. Calcium carbonate 3. Magnesium hydroxide 4. Aluminum hydroxide |
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What do antacids do?
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Neutralize acid
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Do antacids inhibit secretion of acid?
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No they do not
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Name a sodium bicarbonate antacid
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Alka-seltzer
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Tums, Chooz, Mylanta are all what kind of antacids?
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Calcium carbonate
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Sodium bicarbonate or calcium carbonates have longer duration of action
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Calcium carbonates have longer duration of action
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Amphogel is what kind of antacid
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Aluminum hydroxide
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Alternagel and basal gell are what kinds of antacids?
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Aluminum hydroxide
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Aluminum hydroxides have what side effects (Hint: Brain and Muscle) if renal impaired
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Neurotoxicity and Myopathy (weakness)
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Name a magnesium hydroxide
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Milk of Magnesia
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Mylanta, Maalox, and Riopan are all what kinds of antacids?
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Mg-Al hydroxide combinations
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Tablets or liquid formulations of antacids are more effective?
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Liquids - coat the stomach
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Gastric and duodenal ulcers are caused by what organism?
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H. pylori
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H. pylori is what kind of bacteria?
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Gram (-) rod
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H. pylori burrows into the gastric/duodenal mucosa and produces what enzyme?
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Urease
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The ammonia produced by H. pylori's urease damages cells and causes what disease?
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Ulcers
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What is a preferred triple therapy treatment of H. pylori?
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PPI + H2 antagonist + antibiotics
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How long should a patient with H. pylori be treated with triple treatment?
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7 days
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What kind of drugs enhand coordinated GI motility?
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Prokinetic drugs
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Prokinetic drugs do/do not stimulate GI smooth muscle directly?
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Do not.
They influence the activation of innervation to gut = maintain COORDINATION of propulsive function |
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Domperidone
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Dopamine receptor antagonist
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Metaclopramine
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Dopamine receptor antagonist
Serotonin receptor agonist |
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Tegaserod
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Serotonin receptor agonist
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Name a motilin mimetic
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Erythromycin
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Which area inhibits emesis?
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CTZ = chemoreceptor trigger zone
Near area postrema |
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Which prokinetic drug enhances the tone of the LES?
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Metaclopramide (DA antag/5HT ag)
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Does metoclopramide have any effect on lower GI motility?
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No.
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Between DA receptor antagonism and 5HT receptor agonism, where does metaclopramide have its greatest effect?
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5HT receptor agonism
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Tegaserod
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5HT partial receptor agonist
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What is motilin?
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peptide hormone in GI that enhances gastric emptying
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Name a peptide hormone that enhances gastric emptying
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Motilin
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Name two areas of emesis?
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CTZ
NTS |
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H1 Antihistamines can be used as antiemetics. Name four:
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Dramamine (dimenhydrinate)
Diphenhydramine Meclizine Promethazine |
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Dimenhydrinate
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H1 antagonist
Antiemetic |
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How do metoclopramide and Phenthiazines act as antiemetic?
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Block Da receptors in CTZ
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Ondansetron is used as an antiemetic. What does it block?
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Block 5HT receptors in CTZ
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Marijuana can be used as an antiemetic. What does it bind?
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Cannabinoid receptor CB1 in CNS (stimulation of receptor)
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Dronabinol
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Synthetic THC (cannabinoid - marijuana like)
Stimulates CB1 receptor around emesis center |
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What antiemetic drug can also be used to stimulate appetite in AIDS and anorexia?
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Dronabinol
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What drug is used as adjunct for nausea in cancer patients?
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Glucocorticoids
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Carboxymethylcellulose is what kind of antidiarrheal?
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Bulk forming/hygroscopic agent
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Psyllium (Metamucil) is what kind of antidiarrheal?
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Bulk-forming/hygroscopic agent
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Kaolin (clay) is what kind of antidiarrheal?
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Bulk-forming/hygroscopic agent
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Bismuth (Subsalicylate) Pepto-Bismol is what kind of antidiarrheal?
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Bulk-forming/hygroscopic agent
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What antidiarrheal is an anti-motility/anti-secretory agent?
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Opioids
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Opioids act on what receptors when used as antidiarrheal (Antimotility/Antisecretory?)
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mu and delta
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Loperamide
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Antimotility/Antisecretory agent
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What drug is 50X more potent than morphine against diarrhea?
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Loperamide
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Anthraquinones
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Laxative - increase secretion of fluid
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Diphenylmethanes
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Laxative - increase secretion of fluid
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Dioctyl sodium succinate (Colace)
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Stool softener - laxative - increase secretions
Marginally useful in constipation - though widely used |
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Sulfasalazine
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5-aminosalicylate
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Olsalazine
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5-aminosalicylate
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Infliximab
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Remicade
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Which 5-aminosalicylate has the worst side effect profile?
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Sulfasalazine
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