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33 Cards in this Set
- Front
- Back
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Sodium bicarbonate advantage
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soluble
rapid acting |
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Sodium bicarbonate disadvantage
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short duration
possible systemic alkalosis fluid retention in pts with HF and HTN |
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Sodium bicarbonate problem with renal insufficiency
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acid rebound
belching and gastric distention due to CO2 |
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Sodium bicarbonate dose limit
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16-17g (200mEq) qday
for elderly and renal pts: reduce by half |
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calcium carbonate advantage
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cheap
rapid acting high capacity |
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calcium carbonate disadvantage
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cause hypercalcemia
Milk Alkali Syndrome --> kidney stone intense acid rebound constipation |
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calcium carbonate limit dose for chronic use
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8g/day
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magnesium hydroxide advantage
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strong neutralier
no gas, no belching |
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magnesium hydroxide disadvantage
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slower acting
cause diarrhea with chronic use eliminated by the kidneys, thus can accumulate to toxic level in elderly and renal pts. |
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Why Aluminum hydroxide is a bad preparation
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relatively insoluble
slower acting low neutralizing power cause constipation phosphate depletion tastes bad |
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Why is cholinergic antagonist no longer used for acid-peptic disorder?
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Ach is not the only mediator for H+ secretion
Reduce basal H+ by 40-50% H+ secretion is the least sensitive to anticholinergics |
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3 modes of action of H2 receptor antagonists
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competitive antagonist of H2 receptors
Decrease acid secretion decrease pepsin secretion |
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4 H2 receptor antagonists
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cimetidine
famotidine ranitidine nazitidine all equal efficacy |
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2 mechanisms of H2 antagonist to decrease acid secretion
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block Histamine binding to parietal cell
decrease response of parietal cells to direct stimulation by gastrin or Ach in presence of H2 blocker |
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Advatantages of H2 antagonists
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decrease basal acid secretion for few hrs
Little or no H+ rebound decrease food-stimulated secretion nocturnal acid secretion inhibited to greater extent than meal-stimulated acid secretion |
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Cimetidine (Tagamet) doses
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active ulcer: 300mg qid, 400mg bid, 800mg hs
Prevention of recurrence: 400mg hs |
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Cimetidine SE
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well tolerated
diarrhea dizziness in elderly: hallucination, confusion, slurred speech DI - inhibit CYP1A2, 2C19, 2D6, and 3A4 |
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Ranitidine (Zantac) doses
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150mg bid
300mg hs |
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Ranitidnie SE
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fewer SE than Cimetidine (headache, fatigue, confusion, diarrhea)
less inhibition of drug metabolism |
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Famotidine (Pepcid) doses
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20mg bid or 40mg hs
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Advantages of PPIs
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inhibit both fasting and meal-stimulated secretion
block final common pathway of acid secretion - proton pump most potent as acid suppressant (98% up to 24 hr) equal efficacy amongst PPIS |
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Mechanism of action of PPIS
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prodrug
activated in acidic environment to sulfenamide covalently bind to cysteine residue of H+, K+ ATPase catalytic subunit |
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Why should we give PPIs 30-60 min before first of day?
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only 10% of proton pumps actively secrete acid in the fasting state
peak serum conc of PPI coincides with maximum proton pump secretion, which is stimulated by food. |
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Zollinger-Ellison Syndrome
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hypersecretory condition, produce the greatest amt of acidity
give PPIs at twice the dosage |
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Enzymes metabolize PPI
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CYP3A4 and 2C19
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PPI interaction with Clopidogrel
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Clopidogrel: prodrug, metabolized by 2C19
PPIs can inhibit 2C19, mainly in omeprazole, least with pantoprazole |
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PPI side effects
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safe drug
diarrhea, nausea, abdominal pain bone fractures: decrease bone resorption by inhibiting H+ secretion from active osteoclast |
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Sucralfate (Carafate)
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complex of Al(OH)3 & sulfated sucrose
protective agent that enhance mucosal defense Administer at least 2 hrs after other drugs |
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MOA of Sucralfate
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binds to cationic groups in protein in ulcers or erosion
stimulates secretion of PG from GI mucosa forms complex gel with mucus, decreasing mucus degradation by pepsin. |
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SE of Sucrafate
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constipation, dry mouth, nausea, vomiting
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Effects of Misoprostol (CYTOTEC)
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inhibit histamine-stimulated cAMP production --> decrease H+ production
increase mucus secretion increase mucosal blood flow increase HCO3- secretion accelerates cell healing |
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Misoprostol SE
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diarrhea, abdominal cramps
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Misoprostol contraindication
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in women with child-bearing potential because of stimulant effect on uterus.
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