Week 6: Acid-Reducing and Cyto-protective agents Flashcards
Antacids indications
Used for mild intermittent acid reflux/heartburn, GERD - symptom control
- may be used as adjunct therapy for PUD - does not treat the PUD, just for symptom control
Antacid formulations
- aluminum hydroxide
- magnesium hydroxide
- calcium carbonate
Antacid MOA/pharmacodynamics
- neutralizes stomach acid making it more basic
- antacids are weak bases that interact with hydrochloric acid in the stomach to reduce gastric acidity and increase pH
Antacid pharmacokinetics
- Aluminum and magnesium hydroxide are not absorbed with normal use
- calcium carbonate is absorbed if taken with Vitamin D
Antacid cautions/ contraindications
- avoid aluminum and magnesium-based antacids in renal impairment (renally excreted) - think metalic
- antacids should be separated from other medications by at least 2 hours to avoid interactions - take 1 to 3 hours after meals
- contact provider if using for longer than 2 weeks
Antacid ADRs
Aluminum and Calcium-based antacids can cause constipation
Magnesium-based antacids can cause diarrhea (think Milk of Magnesia)
Sucralfate (carafate) and Misoprostol (Cytotec) are examples of what type of medication?
Cytoprotective agents
Sucralfate (Carafate) indications for use
prophylaxis and treatment of moderate to severe peptic ulcer disease
Sucralfate (Carafate) pharmacodynamics
- True cytoprotective - selectively bind to necrotic ulcer tissue, covering it and acting as a barrier to outside stimuli such as acids
Sucralfate (Carafate) Cautions/ contraindications
- should be taken on an empty stomach prior to meals
- instruct patient to separate the use of this medication and others - take other mediations at least 2 hours before or 6 hours after taking this medication - affects absorption of other drugs
Contains aluminum - can cause constipation
Misoprostol (Cytotec) MOA
- G-protein inhibitor - turns off the secondary messenger which turns off the gastric proton pump
- synthetic prostaglandin (vasodilation, uterine contraction, decreased gastric acid secretion, and increases mucosal thickness)
Misoprostol (Cytotec) cautions and contraindications
- Avoid in pregnancy and lactation - pregnancy category X -
- should be taken with food
- use with caution in renal impairment
GERD meds
Misoprostol (cytotec) ADRs
- diarrhea, abdominal pain, nausea, postmenopausal bleeding, headache
What are the 3 types of receptors on the parietal cell that can be stimulated to cause the production of acid or blocked to reduce the production of acid?
1) acetylcholine 2) gastrin 3) histamine
To what drug class do Ranitidine and Famotidine belong?
Histamine 2 Receptor Antagonists (H2RAs) “-tidine”
Histamine 2 Receptor Antagonists (Zantac, Pepcid, Tagamet) MOA
- Reversibly competitive inhibition of histamine at H2 receptors of the gastric parietal cells, thus inhibiting gastric acid secretion - reduces stomach acid by 35 to 50%
- prevents the progression of GERD
Potency in controlling gastric acid secretion
- Ranitidine is 5 to 12 times more potent than cimetidine
- Famotidine is 30 to 60 times more potent than cimetidine
Which H2RA drug has the most potential for ADRs?
Cimetidine (Tagamet) - has greater androgen effects
- CNS effects (confusion, agitation)
- gynecomastia and impotence
- multiple drug interactions because is uses several isoenzymes - Alot of CYP 450 involvement
H2RA cautions/ contraindications
- caution in renal impairment
- safe in pregnancy (except Cimetidine)
- approved in pediatrics (except Cimetidine)
H2RA (Pepcid, Zantac, Tagamet) ADRs
headache, dizziness, confusion, agitation, psychosis, depression, blood dyscrasias (agranulocytosis, granulocytopenia, thrombocytopenia, and aplastic anemia)
Proton Pump Inhibitors examples and indications for use
- Omeprazole, Pantoprazole, Esomeprazole (-prazole’s)
- used for duodenal and gastric ulcers, erosive gastritis, Zollinger-Ellison syndrome, GERD
- peptic ulcer disease as part of the treatment for H-pylori
Proton pump inhibitors MOA
Inhibit gastric proton pumps specifically, the H+/K+-ATPase pump located on the parietal cells to suppress acid secretion
- reduces acid secretion by more than 90%
- inhibitor that turns off the proton pump that moves hydrogen ions into the stomach where they combine with chloride in the stomach which forms HCl acid
- decreases production of stomach acid for up to 72 hours
PPI cautions/contraindications
- metabolized in the liver - use cautiously in pts with hepatic dz and in elderly
- Omeprazole and Plavix drug interaction - CYP2C19 - decreased effectiveness of Plavix when taken with Omeprazole
- Drug absorption of acid drugs is reduced (ex. calcium needs an acidic environment to be absorbed)
- Esomeprazole, omeprazole, and lansoprazole safe in pregnancy and pediatrics
- Pantoprazole and Rabeprazole not safe in pregnancy;
PPIs ADRs
- nausea, diarrhea, headache, abdominal pain,
Long term use (not recommended) can lead to osteoporosis and bone fx., C-diff infections, hypomagnesemia, and Vitamin B12 deficiency - calcium needs an acidic environment to be absorbed
PPIs clinical use
- combined with antibiotics to treat H. pylori
- Used for 8 weeks to treat GERD then weaned off - may double dose for 4 weeks than decrease dose for 4 weeks then wean off
- smoking stimulates the nicotinic acytylcholine receptors in the gastric cells - increases gastic acid secretion - counseling patient to stop smoking can significantly decrease GERD symtoms
H. Pylori triple therapy regimen
1) PPI once or twice daily
2) Amoxicillin 1gm BID
3) Clarithromycin 50mg BID
Take above for 7 to 10 days (up to 14 days)
OR (w/ PCN allergy)
replace #2: Metronidazole 500mg BID
Take triple therapy with above for 10 to 14 days
PUD Treatment - dosing
