Acid-Controlling Drugs: Antacids, H2 Receptor Antagonists, PPIs Flashcards
What is hydrochloric acid and what does it do?
- Secreted by parietal cells stimulated everytime you eat food
- Maintains stomach pH of 1 to 4
- Acidity aids in proper digestion of food and defenses against microbial infection via the GI tract
- Secretion also stimulated by:
Large fatty meals
Emotional stress
Antacids Mechanism of Action:
- do NOT prevent the overproduction of acid, but helps to NEUTRALIZE acid secretions
- buffer pH levels and neutralize it
- do NOT target recpetors
- increases pH
- made of salts: aluminum, calcium, magnesium, sodium
MOA:
- promotes gastric mucosal defense mechanisms by stimulating secretion of:
1. mucous: protective barrier against HCl
2. bicarbonate: helps buffer acidic properties –> counteracts acids making it more basic (increase pH, lower acidity)
3. prostaglandins: prevent activation of proton pump
Antacids Indications:
acute relief of symptoms associated with:
- peptic ulcer disease (PUD)
- gastritis
- gastric hyperacidity
- heartburn
Antacids Contraindications:
- known allergy
- GI obstruction
> antacids may stimulate GI motility (increased GI motility –> obstruction
–> swollen stomach –> stomach could burst)
> undesirable because of the presence of an obstruction process requiring surgical intervention - Renal failure or electrolyte imbalance (heavy metals can accumulate and cannot be excreted by the kidneys)
> potential toxic accumulation of electrolytes in the antacids themselves (especially magnesium)
Side effects of antacids are…
- Minimal; depends on the compound used
- Overuse: metabolic alkalosis (because acid has been reduced too much)
- Aluminum and calcium can cause constipation
- Calcium can cause kidney stones, rebound hyperactivity
- Magnesium can cause diarrhea and can’t be used in renal failure
- Calcium carbonate: produces gas a and belching; often combined with simethicone (antiflatulent) to reduce the gas
What are 3 common antacids?
- Milk of Magnesia (Phillips)
- to treat peptic ulcers
- diarrhea
- dangerous to take everyday if the p.t. has a chronic condition - Calcium Carbonate (Tums)
- do not give with renal failure (constipation, kidney stones)
- used as a calcium supplement - Bicarbonate Salt (Alka-Seltzer)
- highly soluble
- neutralizes acids fast
- metabolic alkalosis if used too much –> there’s ;less acid because it’s neutralizing too much of the acids
- people with heart disease or HTN should not take this because of too much sodium it has
What are some Acid-Related diseases?
- peptic ulcer disease
- helicobacter pylori. (H. pylori)
- Stress related mucosal damage
What are there different types of acid controlling GI drugs?
- Antacids
- H2 antagonists
- Proton pump inhibitors (PPIs)
What is the mechanism of action for histamine 2 receptor antagonists?
- reduce acid secretion
MOA:
- competitively block the H2 receptor of acid-producing parietal cells (HCl)
- increases pH in the stomach (less acidic environment)
H2 Antagonists Indications:
- Gastroesophageal reflux disease (GERD)
- Peptic ulcer disease (PUD)
- Erosive esophagitis
- Adjunct to control upper GI bleeding
H2 antagonists Side effects:
- Very few adverse effects
- Central nervous system adverse effects in elderly patients include: disorientation and confusion
- Famotidine prescribed most often
- Thrombocytopenia (low platelet count) has been reported with famotidine
- Smoking has been shown to decrease the effectiveness of H2 antagonists
- For optimal results, H2 receptor antagonists are taken 1-2 hours BEFORE antacids (to counteract meds. that require the HCL in the stomach to break them down –> this affects food nutrition/absorption –>this med is given to reduce acid)
- no heavy metal poisoning
Common medication used for H2 antagonist
Famotidine
Proton Pump Inhibitors Mechanism of Action
PPIs bind directly to the hydrogen-potassium-ATPase pump mechanism and irreversibly inhibit the action of this enzyme, which result in a total blockage of hydrogen ion secretion from the parietal cells
MOA:
- parietal cells release positive hydrogen ions (protons) during HCL
- irreversibly bind to H+/K+ ATPase enzymes
- Results in achlorhydria - all gastric acid secretion is temporarily blocked
- prevents movement of hydrogen ions out of parietal cells into the stomach –> no hydrogen = no HCl
- works at cellular level –> stops proton pump
What are some common meds for PPIs?
- Lansoprazole (Prevacid)
- Omeprazole (Prilosec)
- Pantoprazole (Protonix) –> less common; hospital given IV
PPI Indications
- GERD
- Erosive esophagitis
- Short-term treatment of active duodenal and benign gastric ulcers
- NSAID-induced ulcers
- Treatment of H. pylori-induced ulcers
- Given with an antibiotic
