gi pharm Flashcards
drug classes for GI issues
H2 receptor antagonists Proton pump inhibitors Mucosal Protectants Antacids Antiemetics
tx h. pylori**must have confirmed h. pylori to begin tx
Several ANTIBIOTICS + gastric acid inhibitor
Why combination therapy? not easy, decrease risk resistance
Minimize resistance, H. pylori likes acidic environment
- most ABX don’t like acidic environment
Length of Rx:10 – 14 days
Adherence? drug expensive
About $200 with up to 12 pills
how to tx gastric acid production?
- block H2 (histamine) receptors in stomach
2. inhibit proton pump at parietal cells inside stomach
H2 receptor antagonistscimetidine (Tagamet) - older drugfamotidine (Pepcid) - newer and most used
MOA: Block H2 receptors in the stomach
- Reduces gastric acid secretion by 60-70%
- Increases stomach pH
Route: PO, IV
Give at least 1 hour apart from antacids
Indications: GERD, PUD, ulcer prophylaxis, heartburn/dyspepsia
anything for overproduction gastric acids
can be given ulcer prophalaxis bc aspiration pneumonia risk
H2 receptor antagonists - adverse reactions
cimetidine (Tagamet) - older drug
famotidine (Pepcid) - newer and most used
Adverse Effects
Well tolerated
CNS effects in elderly
Slight ↑ risk for pneumonia in elderly
Interactions
Inhibits CYP 450 enzymes (older agents)
Newer generation H2RAs do not have this problem (ex. Pepcid)
Safety Alert
Can increase levels of warfarin, phenytoin, theophylline
Give IV form slowly to avoid bradycardia
proton pump inhibitors - prazoles
omeprazole (Prilosec)
pantoprazole (Protonix)
esomeprazole magnesium (Nexium)
MOA: Binds to proton pump
- Inhibits the hydrogen potassium ATPase enzyme system (proton pump)
- Irreversibly inhibits the secretion of HCl
More effective than H2RA
Indications: short term treatment of PUD and GERD
what is the primary driver of gastric acid production?
secretion of HCL
proton pump inhibitors - prazoles
omeprazole (Prilosec)
pantoprazole (Protonix)
esomeprazole magnesium (Nexium)
Adverse reactions - BONE LOSS w osteoporosis
Adverse Effects
Short-term: Relatively Safe
Long-term: Increased risk for Pneumonia, BONE LOSS/hip fx, stomach CA
Interactions
A few interactions
Nursing Implications
Short term use only
Class: Mucosal Protectant
sucralfate (Carafate)
Unique drug composed of:
- Sucrose-base
- Aluminum hydroxide
MOA: Alters when exposed to gastric acid
Sticky, thick gel - protective barrier within stomach
Indication Duodenal ulcers (FDA-approved), gastric ulcers (+evidence)
Mode of delivery
PO – tablet or suspension
Take 2 hours apart
**take other drugs first!!
Adverse Effects
No major
May cause constipation
Interactions
DECREASED DRUG ABSORPTION
major forms of antacids and side effects (4)
Al + Mg - Maalox, Mylanta - balanced approach
aluminum (Al) - Amphojel - constipation
calcium (Ca) - Tums - constipation
magnesium (Mg) - milk of magnesia - diarrhea
Al + Mg - Maalox, Mylanta - balanced approach
antacids
MOA: Neutralizes acid by approximately 50%
Ex. MgOH + HCl - MgCl + H2O
Indication: PUD (healing) GERD (symptoms) Stress ulcers (prophylaxis) What about heartburn and indigestion? - some don't get relief
Adverse effects:
Diarrhea or constipation
Acid rebound
Interactions:
Chelation - interaction w other drugs that won’t let other drug absorb
Altered gastric absorption of many drugs
Separate from other drugs by 1-2H
ANTIEMETICS: DRUG THERAPY FOR NAUSEA
SEROTONIN BLOCKERS;
ANTIHISTAMINES - ANTICHOLINERGICS;
DOPAMINE ANTAGONISTS- PROKINETCS
antiemetics - serotonin blockers
ondansetron (Zofran)
MOA: blocks serotonin receptors in the trigger zone in the brain and in the afferent vagal nerves in the stomach and small intestine
Give PO or IV Use to treat N/V
Especially chemotherapy/radiation-induced
Adverse reactions:
common - usually mild h/a, diarrhea, dizziness
Serious: serotonin syndrome
Be aware of other drugs that affect serotonin - SSRIs, SNRIs, TCAs, MAIs, buspirone, tramadol
antiemetics - antacids
dimenhydrinate (Dramamine)
meclizine (Antivert)
hydroxyzine (Vistril)
- no IV (thrombo, gangrene, tissue)
MOA: blocks the release of histamine H1 receptors in the inner ear
Indication: treatment of DIZZINESS and nausea
- antiemetic and antivertigo associated with motion sickness
Adverse reactions: sedation, drowsiness, dizziness AND anticholinergic effect
FALL RISK
antiemetic - Dopamine Antagonists: Prokinetic agent metoclopramide (Reglan)
MOA: Blocks dopamine receptors, increases the tone of the lower esophageal sphincter (GERD), increases peristalsis in both the stomach and the intestine (diabetic gastroparesis)
Indications: N/V associated with chemo/radiation/opioids, GI motility issues, and paralytic ileus
SE: sedation
Severe: Extrapyramidal symptoms (EPS) (w/ antipsychotic meds), restlessness, neuroleptic malignant syndrome
