GI drugs Flashcards
Antacids drugs
Al (OH)3
Mg (OH)2
CaCO3
Antacids description
Weak bases increase the pH of the stomach
->pepsin inactivation
Antacids Mechanism
Forms a salt and H2O
Very fast effect
Antacids Indication
GERD
GASTRITIS
PUD
Antacids PK
AL(OH)3 may decrease bioavailability of tetracyclines, digoxin, and antimuscarinics
Antacids contraindications
Al(OH)3 -> constipation
Mg(OH)2 -> diarrhea
CaCO3 -> Nephrolithiasis and constipation -> fecal impaction
H2 blockers
Cimetidine (1st gen) 2nd gen: Famotidine Ranitidine Nizatidine
H2 blockers description for peptic ulcer disease
90% reduction of HCl** secretion after a single dose
Promote healing of ulcers
Recurrence is common when monotherapy is stopped
H2 blockers mechanism for PUD
Block the Gs mediated increase in cAMP that activatges the H+/K+ pump
2nd gen do not inhibit CYP450 and are longer actring than cimetidine
H2 PUD Indication
Acute stress ulcer
Prevent aspiration PNA preoperatively
H2 PUD PK
Cimetidine inhibits CYP450 ->many drug interactions
H2 PUD adverse/contraindications
**Cimetidine crosses the BBB and is prolactin simulating and anti-androgenic -> gynecomastia*
Nausea, HA & dizziness
Proton pump inhibitor PUD drugs
Omeprazole Esomeprazole Lansoprazole Rabeprazole Pantoprazole ...basically prazoles
Proton pump inhibitor PUD description
Nearly 100% reduction in HCl
Activated after transport into parietal cell (prodrug)
Also support platelet aggregation and maintain clot integrity -> hemorrhagic ulcers
Proton pump inhibitor PUD mechanism
Covalent bond formation with cysteine residue on H+/K+ ATPase within the parietal cell canaliculi -> irreversible inactivation
Proton pump inhibitor PUD Indication
GERD Gastric ulcers MEN I ZE syndrome H pylori (with antibiotics) NSAID induced ulcers
Proton pump inhibitors PUD PK
Omeprazole inhibits Warfarin, phenytoin, diazepam and cyclosporine
Proton pump inhibitor PUD Adverse/Contraindications
Nausea and diarrhea are possible, but they are generally well tolerated
Prolonged use of PPI and H2 -> decrease bioavailability and B12, disgoxin and ketoconazole (acid required for absorption)
GI and respiratory infections
Pancreatitis
Hepatotoxicity
Interstitial nephritis
Antimicrobials used against H pylori
Clarithromycin
Amoxicillin
Metronidazole
Tetracycline
Clarithromycin, Amoxicillin, Metronidazole, Tetracycline PUD description
Eradication of H pylori -> rapid healing (infection documented with endoscopy, serology or urea breath test)
Clarithromycin, Amoxicillin, Metronidazole, Tetracycline PUD Mechanism
Used as part of triple therapy regimen for 2 weeks -> 2 antibiotics + PPI
Clarithromycin, Amoxicillin, Metronidazole, Tetracycline PUD Indication
H pylori infection
Other combo: bismuth, + 2 antibiotics + PPI or ranitidine
Mucosal protective agents PUD drugs
Sucralfate
Bismuth subsalicylate
Misoprostol
Sucralfate PUD description
Disaccharide; Requires acid to be activated … do not give with PPI’s or H2 blockers
Misoprostol PUD description
- *PGE1 analogue**
* *decrease HCl secretion** and increase mucin & bicarb production via activation of Gi -> decrease cAMP
Sucralfate, Bismuth subsalicylate, Misoprostol PUD mechanism
Polymerization and selective binding to necrotic tissue forms a physical barrier to acid
Stimulates PG synthesis
Sucralfate, Bismuth subsalicylate, Misoprostol Indication
Ulcers
Bismuth may also be helpful in H pylori infections (antimicrobial)
Misoprostol is approved for NSAID induced ulcers but has been replaced by H2 blockers and PPI’s
Misoprostol adverse/contraindications
Diarrhea
Abortion (contraindicated in pregnancy)
Exacerbation of IBD
Prokinetic GI drugs
Neostigmine, Bethanechol
Metoclopramide
Cisapride
Erythromycin
Neostigmine GI description and indication
Cholinomimetic agent
indication- Pseudoobstruction in hospitalized patients
Bethanechol GI Description and indication
Cholinomimetic agent
M receptor only
indication- Gastroparesis
Metoclopramide Prokinetic GI Description/Mechanism
Accelerates gastric emptying and intestinal motility
5-HT and D2 blocker
5HT4=prokinetic
Metoclopramide GI indication
Gastroparesis Emesis (in higher doses) associated with chemo
Metoclopramide GI ae/contraindication
Sedation, Diarrhea
Galactorrhea
EXTRAPYRAMIDAL SYMPTOMS