Antacids & Antiulcers

Question 1

What are antacids used for?

Answer 1

Shot-term, temporary relief of mild pain and sx assoc with PUD/GERD

Question 2

What are the 2 main types of antacids?

Answer 2

Low-systemic agents

High-systemic agents

Question 3

What are the low-systemic antacids? Give examples.

Answer 3

Aluminum-based agents = aluminum hydroxide

Calcium-based agents = calcium carbonate

Magnesium-based agents = magnesium hydroxide/carbonate/trisilicate

Question 4

What are the high-systemic antacids? Give examples.

Answer 4

Sodium-based agents = sodium bicarbonate

Question 5

What are the supplemental antacid agents?

Answer 5

Simethicone

Question 6

What is the MOA of antacids?

Answer 6

Combine chemically with loose hydrogen ions

Results in generation of common by-products:

• Water
• CO2
• chloride salts

Question 7

What are higher doses of Antacids associated with?

Answer 7

Increasing LES (lower esophageal sphincter) tone

Question 8

What is a major possible side effect of antacids?

Answer 8

Antacids don’t reduce acid secretion or production

Rebound acid production IS possible

Question 9

Compare low-systemic agents and high-systemic agents in terms of onset, duration of action, acid neutralizing capacity.

Answer 9

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

Question 10

What does simethicone (a supplemental compound) help with?

Answer 10

A surfactant - decreases surface tension

Aids in expulsion of gas

Question 11

What are the adverse effects of aluminum based antacids (dose-related)?

Answer 11

Constipation
Hypophosphatemia (acute tx for hyperphosphatemia)

Renal osteodystrophy
Encephalopathy

Question 12

What are the adverse effects of magnesium based antacids (dose-related)?

Answer 12

Diarrhea = stool-softening/laxative-like activity

Hypermagnesemia

Question 13

What are the adverse effects of calcium based antacids (dose-related)? What syndrome is associated?

Answer 13

Constipation

Hypercalcemia = milk-akali syndrome resulting in nephropathy and metabolic alkalosis

Hypophosphatemia = effective tx for hyperphosphatemia

Calcium-based kidney stones

Question 14

What are the adverse effects of sodium based antacids (dose-related)?

Answer 14

Gas/flatulence (bicarb burp)
Hypernatremia
Metabolic alkalosis

Question 15

Antacid combinations are frequently used. Why?

Answer 15

To enhance efficacy and reduce side effects

VIa use of lower doses of each and opposing side effects (dose-related)

Question 16

What are some common, important patient factors to take into account with antacids?

Answer 16

Dosage form & palatability

Presence of renal or heart dz

Electrolyte status

Dz assoc with diarrhea and constipation

Question 17

What is important to remember about drug interactions with antacids?

Answer 17

TONS

Avoid antacid + meds co-administration at same time

Take all antacids 1-2 hrs before or 2-4 hrs after other meds

Question 18

What are the anti-ulcer agents?

Answer 18

H2 receptor antagonists

Proton Pump Inhibitors (PPIs)

Surface Acting Agents

PGE1 analogs

Bismuth compounds

Question 19

What are the Histamine Type 2 blockers? Label if po or iv.

Answer 19

-tidine

Cimetidine (po/iv)
Ranitidine (po/iv)
Famotidine (po/iv)
Nizatidine (po)

Some products made with antacids (Ca/Mg)

Question 20

What is the MOA of H2 antagonists?

Answer 20

REVERSIBLY inhibit H2-receptors on basolateral membrane of parietal cell

Question 21

Describe the onset and effectiveness of H2 antagonists.

Answer 21

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

Question 22

What are the adverse effects of H2 antagonists?

Answer 22

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

Question 23

What are the adverse effects of Cimetidine specifically?

Answer 23

RARE (more likely with long-term, high dosing)

Decreases testosterone binding to androgen receptor (weak anti-androgen effects)

Gynecomastia in men
Galactorrhea in women