Week 5: GI Pharmacology Flashcards
What is the drug therapies for GERD and PUD?
H2 receptor antagonists
Proton pump inhibitors
Mucosal protectants
Antacids
Antiemetics
What is the main goal of antacids and sucralfate?
increase protective factors
What is the main goal of H2 blockers, proton pump inhibitors and the treatment of H. pylori ?
decrease aggressive factors
Treatment got H. pylori
several antibiotics and gastric acid inhibitor for 10-14days
Why do we do combination therapy when treating H. pylori?
to minimize resistance
Why is it difficult for patients to adhere to the treatment of H. pylori?
because it is expensive! $200 for 12 pills
What drugs are H2 receptor antagonists?
cimetidine, and famotidine
H2 receptor antagonists MOA
block H2 receptors in the stomach, which reduces gastric acid by 60-70% causing stomach pH to increase
Indications for H2 receptor antagonist
GERD, PUD, ulcer prophylaxis, heartburn/dyspepsia
S/E of H2 receptor antagonist
well tolerated, CNS effects in elderly and slight increase risk for pneumonia in elderly
Drug interactions with H2 receptor antagonists
INHIBITS CYP450 enzyme (older agents NOT pepcid)
Safety considerations for H2 receptor antagonist
can increase levels of warafrin, phenytoin, and theophylline
Give IV form slowly to avoid bradycardia
What drugs are proton pump inhibitors?
omeprazole, pantoprazole, esomeprazole magnesium
MOA of proton pump inhibitors
binds to proton pump inhibiting the proton pump which inhibits the secretion of HCl
Indications for taking proton pump inhibitors
short term treatment of PUD and GERD
S/E of proton pump inhibitors
short term- relatively safe
long term- increased risk dor pneumonia, bone loss/ hip x, and stomach cancer
What class is sucralfate?
Mucosal protectant
MOA of mucosal protectants
alters when exposed to gastric acid to a sticky thick gel, working as a protective barrier for the stomach
Indication for mucosal protectants
duodenal and gastric ulcers
S/E of sucralfate
nothing major, some constipation
Drug interactions with sucralfate
decreased drug absorption, take meds 2 hours AFTER taking sucralfate
What are the 4 major forms of antacids?
- Aluminum (amphojel)
- calcium (tums/calcium carbonate)
- Magnesium (Milk of magnesia)
- Aluminum + Magnesium (Maalox/Mylanta)
MOA for antacids
neutralize acid in the stomach by approximately 50%
e.g.
MgOH +HCl —-> MgCl +H2O
Indications for antacids
PUD (healing), GERD (symptoms), stress ulcers (prophylaxis)
S/E of antacids
diarrhea, constipation, and acid rebound
drug interactions with antacids
chelation, altered gastric absorption of many drugs
What are the 5 classes antiemetic (nausea) medications
- serotonin blockers
- antihistamines
- anticholinergics
- dopamine antagonists
- prokinetics
What drugs are serotonin blockers?
ondansetron
What is the MOA of a serotonin blocker
blocks serotonin receptors in the trigger zone in the b brain and in the afferent vagal nerves in the stomach and small intestine
serotonin causes nausea
What are the indications for taking a serotonin blocker?
N/V, especially if chemo/radiation induced
s/e of serotonin inhibitors
Common= mild headache, diarrhea, dizziness
severe= serotonin syndrome (so be aware of drugs that affect serotonin)
What drugs effect serotonin? So must be careful with serotonin inhibitors
SSRI (citalopram), SNRIs (duloxetine), TCAs (amitriptyline), MAIs. buspirone, and tramadol
What drugs are antihistamines?
dimenhydrinate, meclizine, and hydroxyzine
MOA for antihistamines
blocks the release of histamine H1 receptors in the inner ear
Indications for antihistamines
dizziness and nausea. usually associated with motion sickness
S/E of antihistamines
sedation, drowsiness, dizziness and anticholinergic effects
FALL RISK
What drugs are dopamine antagonist?
metoclopramide
MOA of dopamine antagonists: prokinetic agent
blocks dopamine receptors increases the tone of the lower esophageal sphincter increasing peristalsis in both the stomach and duodenum
Indications for dopamine antagonists: prokinetic agent
N?V associated with chemo/radiation/opioids, GI motility issues, and paralytic ileus
S/E of dopamine antagonists
sedation, extrapyramidal symptoms, restlessness, neuroleptic malignant syndrome
What are extrapyramidal symptoms?
-akathisia: may feel restless
-acute dystonia: involuntary muscle contractions
- parkinsonism
-tardive dyskinesia
-Neuroleptic malignant syndrome
What are the antidiarrheal medications?
diphenoxylate with atropine, and loperamide
what is the MOA for diphenoxylate with atropine, and loperamide
decrease intestinal peristalsis reducing the intestinal effluent
S/E of diphenoxylate with atropine, and loperamide
drowsiness and constipation, fall and drive risk, anti-cholinergic effects of the atropine
SERIOUS: cardiac arrest/arrhythmias
What drugs are in the class 5-aminosalicylates?
sulfasalazine
Indications for taking sulfasalazine
mild to moderate IBD
MOA of sulfasalazine
coverts the intestine into 5-aminsalicyclic acid and sulphapyridine
Why do some with IBD prefer to take just mesalamine?
because sulphapyridine does nothing for IBD and has s/e that pt don’t like
S/E of sulfasalazine
nausea, fever, rash, headache, hematologic disorders
Who can NOT take sulfasalazine?
those with sulfa allergies and those with certain anemias
What drug is a DMARD?
infliximab
MOA for DMARDs
monoclonal antibody which neutralizes TNF-alpha
Indications for taking DMARDs
There are lots but for this section IBD
S/E of DMARDs
IMMUNE SUPPRESSION, infection, heart failure, infusion reactions, and neutropenia
What is often required when taking DMARDs?
therapeutic drug monitoring and biomarker monitoring for inflammation
