Antacids & Antiulcers Flashcards
What are antacids used for?
Shot-term, temporary relief of mild pain and sx assoc with PUD/GERD
What are the 2 main types of antacids?
Low-systemic agents
High-systemic agents
What are the low-systemic antacids? Give examples.
Aluminum-based agents = aluminum hydroxide
Calcium-based agents = calcium carbonate
Magnesium-based agents = magnesium hydroxide/carbonate/trisilicate
What are the high-systemic antacids? Give examples.
Sodium-based agents = sodium bicarbonate
What are the supplemental antacid agents?
Simethicone
What is the MOA of antacids?
Combine chemically with loose hydrogen ions
Results in generation of common by-products:
- Water
- CO2
- chloride salts
What are higher doses of Antacids associated with?
Increasing LES (lower esophageal sphincter) tone
What is a major possible side effect of antacids?
Antacids don’t reduce acid secretion or production
Rebound acid production IS possible
Compare low-systemic agents and high-systemic agents in terms of onset, duration of action, acid neutralizing capacity.
Calcium = RAPID onset, LONG doa, VERY GOOD anc
Aluminum = SLOW onset, SHORT doa, FAIR/WEAK anc
Magnesium = RAPID onset, LONG doa, GOOD anc
Sodium = RAPID onset, SHORT doa, FAIR/GOOD anc
What does simethicone (a supplemental compound) help with?
A surfactant - decreases surface tension
Aids in expulsion of gas
What are the adverse effects of aluminum based antacids (dose-related)?
Constipation
Hypophosphatemia (acute tx for hyperphosphatemia)
Renal osteodystrophy
Encephalopathy
What are the adverse effects of magnesium based antacids (dose-related)?
Diarrhea = stool-softening/laxative-like activity
Hypermagnesemia
What are the adverse effects of calcium based antacids (dose-related)? What syndrome is associated?
Constipation
Hypercalcemia = milk-akali syndrome resulting in nephropathy and metabolic alkalosis
Hypophosphatemia = effective tx for hyperphosphatemia
Calcium-based kidney stones
What are the adverse effects of sodium based antacids (dose-related)?
Gas/flatulence (bicarb burp)
Hypernatremia
Metabolic alkalosis
Antacid combinations are frequently used. Why?
To enhance efficacy and reduce side effects
VIa use of lower doses of each and opposing side effects (dose-related)
What are some common, important patient factors to take into account with antacids?
Dosage form & palatability
Presence of renal or heart dz
Electrolyte status
Dz assoc with diarrhea and constipation
What is important to remember about drug interactions with antacids?
TONS
Avoid antacid + meds co-administration at same time
Take all antacids 1-2 hrs before or 2-4 hrs after other meds
What are the anti-ulcer agents?
H2 receptor antagonists
Proton Pump Inhibitors (PPIs)
Surface Acting Agents
PGE1 analogs
Bismuth compounds
What are the Histamine Type 2 blockers? Label if po or iv.
-tidine
Cimetidine (po/iv)
Ranitidine (po/iv)
Famotidine (po/iv)
Nizatidine (po)
Some products made with antacids (Ca/Mg)
What is the MOA of H2 antagonists?
REVERSIBLY inhibit H2-receptors on basolateral membrane of parietal cell
Describe the onset and effectiveness of H2 antagonists.
Relatively PROMPT onset of actions and relief of GERD Sx = 0.5-2 hrs (longer than antacids, shorter than PPIs)
DQ to BID dosing
Ulcer healing occurs in 4-8 wks
Inhibit 20-50+% of acid production depending on dose and duration
What are the adverse effects of H2 antagonists?
Relatively mild, transient, and infrequent
Primarily GI related = nausea/diarrhea/constipation
Some CNS related = headache
Rare (more likely with long-term, high dosing):
Blood dyscrasias
-neutropenia
-thrombocytopenia
What are the adverse effects of Cimetidine specifically?
RARE (more likely with long-term, high dosing)
Decreases testosterone binding to androgen receptor (weak anti-androgen effects)
Gynecomastia in men
Galactorrhea in women
