GI Acid Controlling Drugs (antiulcers and antacids)

Question 1

Control of gastric acid secretion

Answer 1

Blocks the Ca2+ dependent and cAMP dependent pathway of the parietal cell in the stomach → Inhibition of H+, K+ ATPase

Question 2

Pharmological therapy

Answer 2

To inhibit secretion
To provide cytoprotective effects

Question 3

Stomach secretion

Answer 3

Hydrochloric acid (HCl)
Bicarb, pepsinogen, intrinsic factor, mucus, PGs

Question 4

Glands of the stomach

Answer 4

Cardiac
Gastric** important, where drugs target
Pyloric

Question 5

Gastric acid secretion

Answer 5

Secretion of H+ ions by parietals →
Stimulate receptors → Activates H+, K+ ATPase proton pump exchange →
PGE inhibits gastric acid by blocking cAMP production

Question 6

Gastric acid secretion receptors

Answer 6

Neuronal: ACh (M3)
Endocrine: gastrin (CCK) → ↑ cystolic Ca2+
Paracrine: histamine (H2) → ↑ cAMP

Question 7

Indirects effects by ACh on gastric secretion

Answer 7

↑ gastrin from G cells and histamine from enterochromaffin cells

Question 8

Drugs that inhibit acid production

Answer 8

Proton pump inhibitors
Histamine H2 receptor blockers
Anti-cholinergics
PG analogues

Question 9

Drugs that neutralize gastric acids (antacids)

Answer 9

Systemic: sodium bicarb, sodium citrate
Non systemic: Magnesium hydroxid, etc.

Question 10

Ulcer protectives

Answer 10

Sucralfate
Colloidal bismuth sulfate

Question 11

Antacids

Answer 11

Neutralize stomach acid and reduce GI pain → treating ulcers
Raising pH 1 point neutralizes 90% of acid

Question 12

Different antacids

Answer 12

Al(OH)3, Mg(OH)2, CaCO3 inactivates pepsin and binds bile salts

Question 13

Adverse effect of antacid:

Answer 13

Constipation

Question 14

Antacid drug interactions

Answer 14

Interferes with gastric absorption of concurrently administered drugs: digoxin, tetracyclines, fluroroquinolones

Question 15

H2 Receptor antagonists MOA

Answer 15

↓ gastric acid secretion via reversible competitive inhibition of H2 receptors on gastric parietal cells

Question 16

Different H2 receptor antagonists

Answer 16

Cimetidine (1st gen), nizaridine, famotidine
Reduce H+ and pepsin (70-90% ↓ in acid)

Question 17

_______ is the preffered H2R antagonist

Answer 17

Famotidine due to high potency and less drug interaction

Question 18

H2 receptor antagonist uses

Answer 18

Gastric and duodenal ulcers from stress, uremic gastritis
Hypersecretory conditions like gastrinoma

Question 19

H2 recptor antagonists are not effective in preventing _______________ ulcers

Answer 19

NSAID induced

Question 20

Proton pump inhibitors

Answer 20

Most potent suppressors of gastric acid secretion
Inhibits gastric H+, K+ ATPase
Diminish daily production of acid by 80-90%

Question 21

Different proton pump inhibitos

Answer 21

Omeprazole, pantoprazole, lansoprazole, rabeprazole
Prodrugs requiring activation, inactive @ neutral pH

Question 22

PPI uses

Answer 22

Gastroesophageal reflex disease (GERD)
NSAID- associated gastric ulcers
Peptic ulcer

Question 23

Adverse effects of PPI

Answer 23

Nausea, loose stools, abdominal pain, constipation
Gastrin levels elevated → gastrin neoplasia

Question 24

Comparing PPI with H2

Answer 24

Omeprazole > cimetidine 30x more potent

Question 25

PGE1 Analog (Misoprotosol)

Answer 25

Prevents NSAID-induced gastric ulcers MOA: ↑ Bicarb secretion, mucus production, mucosal blood flow, epithelial cell growth and ↓ gastric acid secretion

Question 26

Misoprotosol should not be used around ______________ may causes ___________

Answer 26

Pregnant animals, abortion

Question 27

Cytoprotective agents (sucralfate)

Answer 27

Sucrose octosulfate and aluminum sulfate Binds and protects the ulceration site from BA and pepsin activity

Question 28

Effects of sucralfate

Answer 28

↑ mucosal synthesis of PGE and epidermal GF Helps with ulcer healing

Question 29

Sucralfate indications

Answer 29

Treating ulcers Prevents gastritis caused by NSAIDs Needs acid environment so give at least an hour before other acid drugs

Question 30

Sucralfate drug interactions

Answer 30

Interferes with absorption and ↓ bioavailability of H2 antagonists, phenytoin, tetracycline, fluoroquins, digoxin and fat soluble vitamins

Question 31

Gastroduodenal ulceration and erosion (GUE)

Answer 31

PPIs superior to H2 antagonists Misoprostol for humans