1. SCREENING OF ANTIULCER AGENTS
Dr. V.V.P.F’S COLLEGE OF PHARMACY
AHMEDNAGAR (2018-2019 )
(Head, Dept of
Miss. Joshi Uttara L.
M.Pharm (sem 1st )
8. PROTON PUMP INHIBITORS
- Most effective drugs in antiulcer therapy.
- Prodrug requiring activation in acid environment .
- Activated forms binds irreversibly to H+K+ ATPase
and inhibit it.
- Eg –Omeprazole
- The parietal cell of the stomach is activated by
histamine acetylcholine and gastrin.
- In addition to the direct action of gastrin and
acetylcholine on the parietal cell these two agents
may release histamine form a histamine form
storage in the gastric mucosa.
9. MECHANISM OF ACTION
- Prodrugs inactive at neutral pH .
- At pH < 5 rearranges to two charged cationic forms t that
bind covalently with SH groups of H+/K+ATPase and
inactivate it irreversible.
- Also inhibits gastric mucosal carbonic anhydrase.
10. Screening methods
• In vitro method
1) Gastric binding assay .
2) H+/K+ ATPase
• In vivo methods
1) Pylorus ligation in rats
2) Stress ulcer model .
3) Histamine induced
gastric ulcer .
4) Acetic acid induced
5) Ethanol induced
6) Indomethacin induced
ulcers in rats 10
12. 1) H+/K+ -ATPase inhibition assay
• Proton pump > final step in the synthesis of acid by
Incubation of guinea pig gastric mucosa
buffer ATP and test compound
13. Add malachite green (colorimetric agent )
after 30 minutes
Add 15% sodium citrate after 10 sec . For 45
Released of orthophosphate from ATP quantified by
colorimeter at 570 nm
• Percentage inhibition of H⁺/K⁺-ATPase is calculated.
15. 1) Pylorus ligation in rats
• Purpose –
A simple and reliable method for production of
gastric ulceration in the rat.
Based on ligature of the pylorus has been
published by shay et al 1945 .
The ulceration is caused by accumulation of
gastric the stomach
16. Midline abdominal incision is given
Ligation of pylorus
Test compounds are given either orally or
About 17-19 hours after pyloric ligation
Wistar Rat are saturated for 48 hrs. access to
Rats are sacrificed and stomachs are
volume of gastric acid pH no. of ulcer index
and severity is noted.
• ID50 values can be calculated by probit analysis.
• An Ulcer Index (UI) is calculated.
• UI = UN+US+UP × 10-1
Un=Average number of ulcer per animal,
Us= Average of severity score ,
Up= Percentage of animal with ulcer
19. 2)Ethanol Induced mucosal damaged
Intra gastric application of absolute ethanol is a
reproducible method to produce gastric lesions in
• These lesion can be at least partially inhibited by
various drugs such as some prostaglandins
• The protective effect against various irritants has
been called cytoprotective activity.
20. Wistar Rat are saturated for 18 hrs. access to water
After 30 min 99.80% alcohol is given orally.
Rate are sacrificed and stomach dissected out
A circular full thickened area is cut
Evaluated using a light transmission densitometer.
The optical density of the test tissues is
•Exposure of cold conditions to restrained
•Accelerates the occurrence of gastric ulcers.
•Shortens the immobilization time
3) Water immersion induced stress model
Stress induced ulcers were induced by force swimming
in the glass cylinder (height 45cm diameter 35cm)
containing water up to 350C maintained at 350C for 3 hrs
(Wistar rat) Animals were fasted 24 hrs prior to the
24. All stomachs were opened along the greater
curvature ulcer index and % inhibition was calculated.
After the drug treatment (standard/test) animals
were allowed to swim for 3hrs then animal were
dissected stomachs were removed
All the animals were fasted 36 hours before administration of
The animals were divided into groups. each rat was administered
with the 20mg/kg indomethacin orally.
30 min prior to the administration of the indomethacin
standard/test drug was administered.
27. By titrating with 0.01M NAOH using phenolphthalein as
Gastric juice estimated for pepsin
Ulcer index and % inhibition were calculated
The rats were anaesthetized with ether 1 hour latter the
stomach was incised through the greater curvature and
examined for the number of lesion under the dissecting
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