Gastric acid Flashcards
what are 3 types of agents for neutralizing gastric acid secretion for treatment of peptic ulcers?
Antisecretory agents
- Buffers
- Cytoprotectants
What are 4 5HT H2 receptor antagonists?
Cimetidine
- Ranitidine
- Nizatidine
- Famotidine
how do you treat an H. pylori Infection? and why is it beneficial to treat an H. pylori Infection?
- Eradication of H. pylori infection promotes rapid and long-term healing of ulcers
- If someone presents as positive for H. pylori infection, they will often undergo “triple therapy” with antibiotics to eradicate the infection and a proton pump inhibitors to reduce symptoms
some antibiotics: – Amoxicillin – Metronidazole – Clarithromycin – Tetracycline
what are AE of Sucralfate?
Minimal systemic effects
• Constipation (rare and due to aluminum)
▪ Can result in aluminum toxicity in people with chronic kidney failure
what is the MOA of sucralfate?
- A complex of aluminum hydroxide and sulfated sucrose that forms a viscous paste in acidic media (releases aluminum in the presence of acid)
- Paste binds positively charged proteins in the ulcer, forming a protective barrier for ~6 hrs
- Reduces the degradation of mucus via pepsin
- Can stimulate the secretion of mucus, bicarbonate, and prostaglandins from the gastric mucosa
what are 2 drugs that protect the Mucosa?
- Sucralfate
* Bismuth chelate
what is Sucralfate?
a drug that protects the Mucosa
what are AE of Bismuth chelate?
- Nausea
- Vomiting
- Blackening of the tongue and feces
- Tinnitus
- Can result in encephalopathy (Reye’s Syndrome) if renal excretion is impaired
what is the MOA of Bismuth chelate?
Has toxic effects on bacillus and may prevent adherence of H. pylori to the gastric mucosa
- Forms protective barrier over the ulcer and enhances secretion of prostaglandins, mucus & bicarbonate
- May inhibit bacterial proteolytic enzymes
what is Bismuth Chelate?
OTC for treating mild GI symptoms - protects the mucosa!
what can be prescribed with antacids to relieve bloating sometimes associated with antacids?
simeticone
what are AE of Magnesium hydroxide and Aluminum hydroxide gel?
– Magnesium salts cause diarrhea
– Aluminum salts cause constipation
– Mixtures of the 2 can preserve normal bowel function
what is the MOA of magnesium hydroxide, and aluminum hydroxide?
- Magnesium hydroxide is an insoluble powder that forms magnesium chloride in the stomach
- Aluminum hydroxide gel forms aluminum chloride in the stomach
what are the Most common antacids?
salts of magnesium or aluminum
- Magnesium hydroxide
- Aluminum hydroxide
what is the simplest way to treat/reverse the symptoms of elevated gastric acid secretion>
antacids
what is the MOA of an antacid?
- Neutralize acid and thereby inhibit the activity of peptic enzymes
- Can also lead to healing of duodenal ulcers if given for a long enough time…BUT LESS EFFECTIVE FOR GASTRIC ULCERS
what are AE of misoprostol?
- Diarrhea
- Abdominal cramps
- Uterine contractions – Avoid in pregnancy
which EP receptors does misoprostol work on?
prostaglandin EP2/3 receptor
what is the MOA of misoprostol?
• Acts directly on the ECL cells to inhibit both basal and food-induced gastric acid secretion
– Via prostaglandin EP2/3 receptor
• May also contribute to maintenance of the mucosal barrier
– Leads to stimulation of mucin (EP4 receptor) and bicarbonate (EP1/2 receptor)
• Promotes the healing of ulcers
– Can also be used to prevent the gastric damage associated with chronic NSAID use
what is misoprostol?
An oral stable analogue of prostaglandin E1
why do proton pump inhibitors increase risk of gastric cancer?
they MASK gastric cancer - harder to recognize and realize something is wrong with your body
what are AE of proton pump inhibitors?
• Generally well tolerated
• Uncommon – Diarrhea – Rash – Nausea – Abdominal pain – Dizziness – Somnolence – Headache – Mental confusion
• Less Common
– Hypergastrinemia
in what manner do proton pump inhibitors bind to proton pumps?
(irreversibly)
what is the MOA of proton pump inhibitors?
PPI ARE WEAK BASES
Accumulates in the acid environment of the canaliculi of the stimulated parietal cell
Binds to the proton pump irreversibly and reduce the amount of H+ pumped into the stomach lumen
are proton pump inhibitors the most potent for inhibiting gastric acid secretions?
YESSSS!
what are the 5 PPI (proton pump inhibitors) drugs? what is the common ending in their names?
– Omeprazole – Esomeprazole – Lansoprazole – Pantoprazole – Rabeprazole
common ending is “PRAZOLE”
what are AE of 5HT H2 receptor antagonists? are these rare?
yes they are rare
• Diarrhea
- Dizziness
- Muscle pain
- Alopecia
- Rash (transient)
- Confusion in the elderly
- Gynaecomastia, galactorrhea and a decrease (rarely) in sexual function in men (cimetidine only)
- Thrombocytopenia
what is the MOA of 5HT H2 receptor antagonists to reduce gastric acid secretions?
• Competitively antagonize histamine actions at all H2 receptors
– Reduces parietal cell cAMP levels
– Main clinical use is as inhibitors of gastric acid secretion
- Reduce both histamine and gastrin-induced acid secretion
- Decrease basal and food-stimulated acid secretion (60- 80%)
- May also promote healing of gastric and duodenal ulcers
what is an antacid?
a buffer
