Anti-ulcer Drugs

Question 1

Amoxicillin

Answer 1

penicillin of choice for H. pylori treatment –> more acid stable and more than twice the blood levels
- bind PBP –> inhibit transpeptidase –> inhibit cell wall synthesis (CIDAL)
S.E = hypersensitivity

Question 2

Clarithromycin

Answer 2

macrolide of choice for H. pylori treatment –> more acid stabile and lowest MIC 50

• inhibits protein synthesis (50S subunit) (STATIC)
• less GI side effects, lower MIC50 than azithromycin

Question 3

Tetracycline

Answer 3

can be used for H. pylori infections, but DON’T give with antacids (significantly decreases efficacy because of chelation) (STATIC)

• inhibit protein synthesis inhibitors (30S subunit)
• S.E. = GI irritation, photosensitivity, teeth discoloration

Question 4

Rifabutin

Answer 4

• rifamycin antibiotic –> more effective that others BUT toxicity
• inhibits DNA-dependent RNA polymerase (CIDAL)
• S.E. = hypersensitivity, hepatotoxicity, CYP450 inhibition, RED FLUIDS

Question 5

Metronidazole, Tinidazole

Answer 5

newer less frequent dosing (?? mechanism –> possible DNA damage)

• 35-65% of H. pylori resistant
• S.E. = MANY –> GI, CNS, disulfarim rxn, teratogenic, CYP2C9 inhibition (can potentiate warfarin and decrease clearance of H2 blockers)

Question 6

Bismuth Subsalicylate

Answer 6

1 –> antimicrobial - disrupts cell wall, prevents adhesion, inhibits urease
2 –> protects surface - coats, stimulates secretion of mucus PG and HCO3
- Bismuth is active in stomach
S.E. = subsalicylate is causing most S.E. –> vomiting, tinnitus, confusion, hyperthermia, resp. alkalosis
- Bismuth can cause black tongue and stool

Question 7

Muscarinic Receptor Antagonist

Answer 7

Atropine and Pirenzipine (more selective)
- rarely used to treat ulcers because they slow gastric emptying!!!
- competitive inhibitors of ACh
S.E. = CNS, tachycardia, hot-dry skin

Question 8

H2 Receptor Antagonists

Answer 8

Cimetidine, Famortidine, Nizatidine, Ranitidine
- effectively decrease all forms of gastric acid secretion
- highly selective –> no H1 activity
- decrease intracellular cAMP
S.E. = nothing significant orally, IV = bradycardia and hypotension
Cimetidine can cause gynecomastia and galactorrhea at high doses

Question 9

Proton Pump Inhibitors

Answer 9

Esomeprazole/Omeprazole

• most effective agents for reducing gastric acidity –> IRREVERSIBLY block final pathway of acid secretion (H/K ATPase)
• prodrugs (acid labile) needs coating to pass through stomach
• absorbed in small intestine –> circulate and then [ ] in acidified compartments and becomes protonated

Question 10

Buffer acid drugs

Answer 10

Weak bases (—hydroxides)
- buffer stomach acid –> antacids
Drug Interactions –> increase gastric pH
- binds other drugs
- increase gastric emptying
- systemically absorbed –> alkalize urine

Question 11

Simethicone

Answer 11

antifoaming –> decrease gas pain

affects absorption of other drugs

Question 12

Sucralfate

Answer 12

not an antacid –> it’s a ‘band-aid’ –> attaches to ulcer surface

• mainly used in ICU for stress ulcers
• causes constipation and binds other drugs affecting their efficacy

Question 13

Misoprostol

Answer 13

synthetic prostaglandin –> inhibits cAMP pathway –> less acid secretion

• used for NSAID induced ulcers
• short half-life
• S.E. = diarrhea, nausea, cramping, ab pain
• also used as abortant –> stimulates uterine contractions