1. DRUGS USED IN GIT

2. C. Proton pump inhibitors (PPI):
Are :
Omeprazole
lansoprazole,
dexlansoprazole
pantoprazole,
rabeprazole and
esomprazole

3. Chemically: They are: - weak bases. -At neutral PH, they are
1-stable and
2-lipid soluble,

4. MOA: They irreversibly inhibit H -K ATPase
inhibit the exchange of H and K
(at the final step of acid secretion)

5. Note :
H -K ATPase found on apical membrane of parietal cells in the stomach and this enzyme primarily responsible for the acidification of the stomach contents and the activation of the digestive enzyme pepsin.

6. Mechanism of action of PPI:
They reach the parietal cells from the blood and become active (where PH is about 1).
As shown in the following

8. MOA OF PPI Blood sulfonamide Partietal cell canalicul (PH=1) e active
ionized
sulfonamide
Covelant bond
Sulfahydryl gr of enz.

9. Omeprazole kinetics 1- Long peroid of inhibition of acid.
2-20 mg of omeprazole decreases acidity by about 90%
3- given in enteric-coated
4- t1/2=1 hr
5- Excreted in the urine.
6- Metabolized by cytochrome P450 oxidase.

10. Clinical indications of of PPI:
-DU & GU.
-GERD.
-Zollinger-Ellison syndrome.

11. Side Effects:
-Nausea, vomiting, diarrhea, constipation, hypersensitivity and skin rash.
-Inhibits metabolism and absorption of many drugs, vit. and metals

12. Carcinogenic outcome with PPIs :
-Suppression of acid secretion increase gastrin release carcinoid tumors.
-Decreased gastric acidity bacterial
overgrowth
nitrosoamines.

13. 2.Nutralization of the acidity :
Antacids are basic substances that
1-Decrease the acidity by neutralization of HCl .
2-Protect gastric mucosa.

14. Uses of Antacids:
- ulcer .
- dyspepsia

15. Antacids: a-Magnisium Hydroxide: React quickly ,
Mg trisilicate reacts slowly
with HCl MgCl intestinal secretion
Carbonate .

16. b-Aluminum Hydroxide:
1-Reacts with HCl AlCl intestinal secretion
insoluble salts
2-affect colonization
3- PGE
S.E:
constipation,
hypophosphaemia ………

17. C- NaHCl :
reacts with acids,
causing alkalosis.

18. d-Ca and bismuth containing antacid:
They may cause:
1- rebound acid hypersecretion,
2- Encephalopathy.
e-Alginic acid
F- Dimethicone:
it is a silicone polymer that decrease the surface tension of S.I. (anti-foaming agent).

19. 3-Enhancement of mucosal Resistance :
A. Antimicrobials:
2 ABCs + PPI

20. B-site protection
1-Colloidal Bismuth.
Mechanism of drug action:
1- forming a coat covering the ulcer.
2- PGs .

21. 2. Sucralfate:
It is a basic Al salt of sucrose octasulphate or octaphosphate.

22. Mechanism of action:
1-In ulcer base FORMING a thick paste
2-It increase PG secretion.
Uses:
1.GU
2-DU
3-Gastritis.
Side effects:- Constipation.

23. C.Cytoprotection:
PGs :
Mechanism of action
1. increase mucous and HCO3.
2.Maintains mucosal microvasculature.
3.Block H diffusion to mucosa.
4.Enhance cell repair in the mucosa.

24. Contraindindications:
Misoprostol:
Is a synthetic analogue of PGE1
MOA: Same as PG
Uses:
1. DU & GU.
2. NSAIDs ulcer .
Contraindindications:
Pregnancy. .

25. Thank you