61-62: GI protectants Flashcards
Drugs that increase GI motility
-laxatives
-prokinetic drugs
Drugs affecting gastric secretion
-Antacids
-H2 histamine receptor antagonists
-Proton Pump Inhibitors
-Protectants
Drugs that reduce GI motility
-antidiarrheals
-anti-emetics
Acid-peptic disease
-non-ulcer dyspepsia (indigestion)
-gastric and duodenal ulcers
-GERD
-hypersecretory states (Zollinger syndrome)
Physiologic control of GI secretions
-slide 10-13
Antacids
-systemically absorbed: NaHCO3 and CaCO3
-minimally absorbed: Al(OH)3 and Mg(OH)2
NaHCO3
-systemic
-high efficacy
-alkalosis, fluid retention, gas)
-alkaseltzer
CaCO3
-systemic
-moderate efficacy
-hypercalcemia, nephrolithiasis, milk-alkali syndrome, CO2
-Tums and Rolaids
AlOH3
-minmally absorbed
-high efficacy
-contipation, hypophosphatemia
-encephalopathy if absorbed
-AlternaGEL and Maalox
MgOH2
-minimal absorption
-high efficacy
-diarrhea
-CNS toxicity if absorbed
-Maalox and Rolaids
AlternaGEL
-AlOH3
-antacid
-minimal absorbed
Tums
-CaCO3
-systemic
-mod efficacy
-antacid
Maalox/Mylanta
-AlOH3 and MgOH
-minimally absorbed
Rolaids
-CaCO3 and MhOH
-antacid
Alka-seltzer
-ASA and NaHCO3
Gaviscon
-sodium alginate + antacids
-viscous, weak base
-prevents reflux
-effective in GERD
Commercial antacids
-AlternaGEL
-Tums
-Maalox.Mylanta
-Rolaids
-Alka-seltzer
-Gaviscon
Histamine Receptor Antagonists
-slide 16-19
Cimetidine (tagamet)
-competative antagonist of H2
-reduce gastric secretion in response to histamine, gastrin, acetylcholine
2nd gen H2 blockers
-Rantidine (NO_
-Nizatidine
-Famotidine
Nizatidine (axid) and famotidine (pepcid
-2nd gen H2 antagonists
-reduce acid secretion in response to histamine, gastrin, acetylcholine
-longer hlaf life
-fewer CYP effects
-greater potency
-absorbed quickly to reduce parietal cell function
Proton Pump inhibitors
mech slide24-25
PPI drugs
-Benzimidazoles
-six ring next to 5 ring
-or Vonoprazan (P-CAB)
Benzimidazoles (PPI drugs)
-Esomeprazole (nexium)
-omeprazole (prilosec)
-lansoprazole (prevacid)
-rabeprazole (aciphex)
-pantoprazole (protonix)
-dexlansoprazole (dexilant)
Omeprazole (prilosec) vs eSomeprazole (nexium
-omeprazole racemic
-eSomeprazole is S enantiomer
-more potent
PPI action
-must be absorbed in SI, circulate and then be taken up by parietal cells = SLOW onset
-prodrugs activated by acidic pH in parietal cell
-irreversible inhibitor of H/K ATPase
-short plasma half-life (1 hour) but long duration of action due to covalent inhibition (>24 hours) and slow turnover of proton pumps
-hypergastrinemia occurs and may result in rebound hypersecretion of gastric acid upon drug withdrawal
Acid rebound
-inc acid secretion upon withdrawal of acid suppressing medications
-reduced gastric acid removes somatostatin’s inhibition of gastrin secretion (HYPERgastrinemia)
-tolerance to H2 antagonists can occur
PPI risks
-inc risk of infection
-vitamin b12 deficiency
-dec Ca absorption/inc bone fractures
-dementia?
-maybe bc calcium is dec and PTH is inc which takes Ca out of bone to replace blood levels
Vonoprazan
-PPI
-K-competative acid blocker (P-CAB)
-adbantages: faster acid suppresion, not prodrug, not influenced by meals, very stable in low pH
Mucosal Protective Agents
-Sucralfate (Carafate)
-Misoprostol (Cytotec)
-affect secretion