Pharm: Antacids and Anti-Ulcer

Question 1

what is the purpose of antacids and how do they work?

Answer 1

short-term, temp relief of PUD/GERD symptoms
DONT alter acid production
-combine chemically with H+ ions (water, CO2, Cl can be formed as by product depending on type of salt in antacid)

Question 2

what are the types of antacids?

Answer 2

1. low-systemic agents
2. high-systemic agents
3. supplemental agents

Question 3

low-systemic agents

Answer 3

• aluminum salts (constipation) works quickly
• calcium salts (constipation)
• magnesium salts (diarrhea) works quickly

Question 4

high-systemic agents

Answer 4

-sodium salts (gas/flatulence “bicarb burp”, hypernatremia)

Question 5

supplemental agents

Answer 5

simethicone (a surfactant that decreases surface tension and helps to expel gas) but labelled “ant-gas”

Question 6

Combining antacids and drug interactions?

Answer 6

• can combine ant-acids to enhance efficacy and lower side effects
• LOTS of drug interactions, take antacids 1-2 hrs before taking other meds or 2-4 hrs after taking meds

Question 7

what are the types of anti-ulcer meds?

Answer 7

1. H2 receptor blockers
2. Proton pump inhibitors (PPI)
3. Surface acting agents
4. PGE2 analogs
5. Bismuth compounds

Question 8

Histamine (H2) Receptor Blockers

Answer 8

-cimetidine, ranitidine, famotidine, nizatidine

MOA: reversibly binds H2 receptors on parietal cells, inhibits 20-50% acid production, relief of GERD sx in 0.5-2hrs

Question 9

Downside to H2 Blockers

Answer 9

AE: N/V/constipation, headache
rare AE: cimetidine decreases testosterone binding (gynecomastia, galactorrhea)
Drug Interactions: cimetidine, ranitidine inhibit CYP450
Pregnancy: only use if necessary

Question 10

Proton Pump Inhibitors

Answer 10

-omeprazole, esomeprazole, lansoprazole, dexlansoprazole, pantoprazole, rabeprazole
MOA: covanlently binds to H/K ATPase at parietal cells (inhibits gastric acid prod by 50-90% by irreversibly inhibiting function of pumps), takes a few days to reach max effect, but lasts 24hrs

Question 11

Downside to PPI

Answer 11

AE: N/V/dyspepsia, CDAD (c. diff assoc diarrhea), headache, myalgia, fatigue, myopathies (rare)
Drug interactions: Omeprazole inhibits CYP450
Pregnancy: only use if necessary (AVOID omeprazole)

Question 12

Surface Acting Agents

Answer 12

-SUCRALFATE
MOA: crosslinks with gastric acid and creates a viscous, sticky polymer that adheres to epithelial cells around ulcer’s crater (band-aid protecting ulcer from acid), may stimulate local PGE mucus production
-used for duodenal ulcers and more

Question 13

Downsides to Surface Acting Agents

Answer 13

AE: constipation (due to aluminum)
Drug Interaction: avoid by taking 2 hrs after eating (may take 4x/day for active ulcers)
*DONT take if in severe renal failure (due to aluminum)

Question 14

PGE2 Analogs

Answer 14

-Misoprostol
MOA: provides protective prostaglandin to gastric mucosa and reduces gastric acid release from parietal cells by stimulating bicarb and mucus production
*used to prevent NSAID induced gastric ulcers in high risk patients, on in cervical ripening and postpartum hemorrhage

Question 15

Downsides to PGE2 Analogs

Answer 15

AE: D w/ or w/o N/V, headache, dizziness

Dont use in pregnancy or IBD

Question 16

Bismuth Compounds

Answer 16

-Pepto, Kaopectate, etc.
MOA: has antimicrobial action, used for reflux, indigestion, diarrhea, can be used in combo with antibiotics for H pylori tx

Question 17

Downsides to Bismuth

Answer 17

AE: constipation, black/dark stools
Drug Interaction: take 2 hrs after food
*dont use with antiplatelets and anticoags, severe renal failure
**ABSOLUTE dont use with GI bleed, salicylate hypersensitivity

Question 18

Treatment of H. Pylori

Answer 18

*must use combination therapy (at least 2 antibiotics and an acid reducer-H2 or PPI), for 10-14 days
-Clarithromycin
-Amoxicillin or metronidazole
(avoid bismuth for 4 weeks prior to urea breath test)

Question 19

Triple Therapy

Answer 19

• 14 days, 3 drugs

- 2x/day

Question 20

Quadruple Therapy

Answer 20

10-14 days

• 2x/day PPI, 3x/day others
• also includes bismuth subsalicylate