PHARM - Ulcers and Reflux

Question 1

2 antisecretory agents

Answer 1

• histamine receptor antagonists
• proton pump inhibitors

Question 2

4 examples of cytoprotective agents and mucosal strengtheners

Answer 2

• sucralfate
• prostaglandins
• bismuth
• antacids

Question 3

histamine receptor antagonists
- MOA
- use
- what happens on withdrawal?
- e.g.

Answer 3

• inhibits histamine (H2) receptor = decreased gastric HCl secretion
• promote healing of duodenal ulcers
• relapse on withdrawal b/c reversible
• e.g. ranitidine

Question 4

proton pump inhibitors (PPIs)
- MOA
- use
- optimum pH
- e.g.

Answer 4

• irreversibly inactivates H+/K+ ATPase pump at the parietal cell luminal surface to decrease HCl secretion (need new pumps to resume secretion)
• most effective anti-ulcer therapy b/c blocks common pathway
• inactive at neutral pH, activated in acidic environment in canaliculi (channels) of parietal cells
• e.g. esomeprazole (Nexium)

Question 5

PPI
- time of administration
- what are they NOT used with

Answer 5

• taken 1h before meals
• not used with other acid-suppressing agents e.g. antacids

Question 6

PPI A/Es

Answer 6

• generally extremely safe
• short-term: headaches, skin rashes, dizziness, N&V
• long-term: osteoporosis, B12 deficiency, C. diff (rare), nephritis (rare)
• can also inhibit CYP450 = reduced metabolism of other drugs

Question 7

sucralfate
- MOA
- how should it be taken
- interactions

Answer 7

• MOA: viscous at acidic pH = adheres to surface of ulcers to act as a barrier to aggressive luminal factors (e.g. acid, pepsin, bile salts) and protect mucosa
• taken 1h before meals
• interactions: don’t take antacids or meals within 30 mins as they can raise stomach pH = no longer viscous

Question 8

prostaglandin analogues MOA

Answer 8

• similar structure to PGI2 and PGE2 = protective in GIT
• inhibit gastric acid secretion, increase mucosal blood flow, increase mucus to protect mucosa

Question 9

misoprostol
- class
- indication
- AEs
- CI

Answer 9

• prostaglandin analogue, similar efficacy to histamine antagonists
• prevention of gastric ulcers, only indicated in Pts using NSAIDs w/ high ulcer risk
• AEs: diarrhoea, nausea, headache, dizziness
• C/I: pregnancy b/c causes uterine contractions = miscarriage

Question 10

bismuth chelate
- class
- indication
- MOA
- AEs
- contraindications

Answer 10

• prostaglandin analogue
• peptic ulcer disease - not first line, often used in combination therapy
• coats ulcer base, forming a barrier to aggressive factors in gastric juice AND moderates direct activity against H. pylori
• AEs: blackening of stools and tongue, bismuth toxicity (kidneys and CNS - not used for long periods)
• C/Is: not to be taken with meals or ANY other meds

Question 11

antacids
- MOA
- indication
- duration of action
- e.g.s

Answer 11

• weak bases that neutralise acid, raising gastric pH and inhibits pepsin activation
• more effective against duodenal ulcers than gastric, OTC relief of indigestion
• 30 min duration on empty stomach, 2h when taken w/ meal
• e.g. Al(OH)3, Mg(OH)2

Question 12

H. pylori

Answer 12

• gram -ve bacteria
• major cause of gastric and duodenal ulcers + class 1 carcinogen for gastric cancer

Question 13

Tx for H. pylori

Answer 13

• CAP: clarithromycin, amoxicillin, PPI

Question 14

why is the pH of venous blood more alkaline than arterial blood

Answer 14

• bicarbonate (weak base), is exchanged with Cl- on the plasma (basolateral) side of the parietal cell, which is where the blood vessels are located