GI meds Flashcards
1
Q
Gastric antacids
A
- Magnesium hydroxide produce Mg salt, which is very poorly absorbed and cause diarrhea.
- Aluminum hydroxide reacts with HCl to form Aluminum chloride, which is insoluble and cause constipation and hypophosphatemia
- Calcium carbonate: Hypercalcemia, nephrolithiasis, and constipation –fecal compaction
- Ca, Mg, Al molecules can chelate tetracyline.
2
Q
H2 antagonists
A
- Ranitidine, Famotidine and Nizatidine are longer acting and more potent than older cimetidine.
- Unlike cimetidine, newer drugs does not produce the antiandrogenic or prolactin stimulating effects.
- They do not inhibit the mixed function oxygenase system in the liver (CYP450 enzymes).
- Most common side effects are nausea, headache, and dizziness.
3
Q
Cimetidine
A
- Cimetidine SE’s - gynecomastia, elevated serum PRL, and confusion in elderly people
- Strong inhibitor of CYP450 system -> slow metab of warfarin, procainamide, phenytoin, BZOs, theophylline, imipramine, and quinidine
4
Q
Omeprazole
A
- In animals, is associated w/gastric carcinoid tumors
- Inhibs the metabolism of warfarin, phenytoin, diazepam, and cyclosporine
- Small increase in resp and GI infxns. Decrease in sr. Mg2+ and hip fx’s w/LT use
- Rarely pancreatitis, hepatotoxicity, and interstitial nephritis
- Prolonged use of PPI and H2 blockers -> decreased bioavailability of B12, digoxin, and ketoconazole bc acid is required for absorption
5
Q
Sucralfate
A
- Sulfated disacch used in PUD
- MOA - drug undergoes polymerization and selective binding to necrotic tissue -> barrir to acid Also stimulates endogenous PG synth
- Sucralfate is INEFFECTIVE w/action of H2 rec blockers or PPI -> needs acidic pH to be activated. Do NOT administer w/antacids
6
Q
Bismuth
A
- Selectively binds ulcer and forms coating, protects from acid and pepsin
- Some anti microbe effect on H. pylori
7
Q
Misoprostol
A
- PGE1. Decreases acid secretion, stimulates mucin and bicarbonate production
- For gastric ulcers induced by NSAIDs
- SE’s: diarrhea, abortions (d/t induction of uterine contractions during pregnancy), exacerbations of BID
8
Q
Metoclopramide
A
- Prokinetic via 5-HT4 agonist activity -> increased gastric emptying and intestinal motility
- Higher doses - anti 5-HT3 and anti-D2 - anti-emetic
- Uses: diabetic, post op gastroparessis, anti-emetic
- Especially useful at high doses against highly emetogenic cisplatin
- SE’s: anti-dopaminergic -> sedation, diarrhea, Parkinson’s
9
Q
Cisapride
A
- Gastroparesis, GERD, and constipation
* SE’s: arrhythmias
10
Q
Cholinomimetics
A
- Neostigmine - used for colonic pseudo-obstruction
* Bethanechol - used in GI and bladder atony. Opposite is atropine
11
Q
Erythromycin
A
- Macrolide. Acts on motilin recs of GIT
- Used for gastric emptying before upper GI endoscopic procedures
- Tolerance develops in gastroparesis
12
Q
Substances that act on area postrema
A
• D2, 5-HT3, opioid/ACh, substance P
13
Q
Aprepitant, Fosaprepitant
A
- NK-1 rec blocker in CNS
- Decreases early and delayed emesis in CA chemotherapy
- Fosaprepitant is used IV
- SE’s: dizziness, fatigue, diarrhea, CYP interaction
14
Q
Prochlorperazine
A
- Blocks D2 recs and muscarinic recs
* SE’s: extrapyramidal sx’s, hypotension, etc
15
Q
BZOs
A
- Antiemetic potency of lorazepam, alprazolam, and diazepam is low
- Beneficial d/t sedative, anxiolytic, and amnesic properties
- Useful in anticipatory vomiting
