1. Gastrointestinal Pharmacology

2. The gastrointestinal tract has many important functions:
Digestive
Excretory
Endocrine
Exocrine

3. Gastrointestinal Pharmacology
Because of the complexity of GI functions and disorders, many classes of drugs are used in the treatment of the various GI disorders

4. We will divide the disorders into groups:
Acid/Peptic Diseases
Vomiting
Motility Disorders
Inflammatory Bowel Disease
Irritable Bowel Syndrome

5. Acid/Peptic Disease
The stomach produces hydrochloric acid, with a pH of about 3
The main purpose of this acidic secretion is to sterilize food as it enters the body

6. In certain situations, this acid can do damage to:
Esophagus
Stomach
Duodenum

7. Acid/Peptic Disease
The stomach produces mucous that lines the stomach and protects the stomach from the acid
Sometimes the stomach does not produce enough of this protective mucous

8. Acid/Peptic Disease
Sometimes the stomach does not produce enough of this protective mucous, this can be caused by: STRESS!

9. If more stomach acid is produced than what the protective mucous lining can handle, the result can be:
- gastritis
- errosions – preulcers
- ulcers (peptic ulcer disease, PUD)

10. Picture of Gastrointestinal Tract

11. Stomach errosion

12. Stomach errosion

13. Acid/Peptic Disease
Sometimes the stomach acid is refluxed into the esophagus
Gastro Esophageal Reflux Disease (GERD)

15. Acid/Peptic Disease
If GERD is severe enough, it can change the lining of the esophagus:
- esophagitis
- errosions
- strictures
- Barrett’s Esophagitis – precancerous

16. Esophageal Stricture

17. Acid/Peptic Disease
Sometimes GERD is caused by hiatal hernia, a herniation of the stomach through the opening in the diaphragm for the esophagus
A hernia happens when part of an internal organ or tissue bulges through a weak area of muscle or any part of a bulb that sticks through a hole where it doesn’t belong

19. Acid/Peptic Disease
Sometimes excess stomach acid production can lead to ulcers of the duodenum as well

21. Acid/Peptic Disease
A rare disorder, Zollinger-Ellison is due to tumors of the pancreas that secrete gastrin, signalling the stomach to produce too much acid, which results in severe gastric and duodenal ulcers

22. Acid/Peptic Disease
Sometimes peptic ulcer disease is caused by bacteria
Helicobacter Pylori
(H. Pylori)

23. Pharmacologic Treatment of Acid/Peptic Disease
Strategies for treating acid/peptic disease are:
- neutralize acid
- decrease acid production
- protect stomach lining
- antibiotics for H. Pylori

24. Pharmacologic Treatment of Acid/Peptic Disease
Antacids are weak bases that help to neutralize acid

27. Pharmacologic Treatment of Acid/Peptic Disease
Antacids are weak bases:
- magnesium hydroxide
- aluminum hydroxide
- calcium carbonate
- sodium bicarbonate

28. Magnesium Hydroxide
Not absorbed by the GI tract
Laxative Effect

29. Aluminum Hydroxide
Not absorbed by the GI tract
Constipating Effect

30. Calcium Carbonate and Sodium Bicarbonate
Are absorbed systemically and can affect the bodies acid base balance

31. Drugs used to decrease acid production
Proton Pump Inhibitors (PPI)
H2 Blockers
- Histamine receptor type 2 antagonists

32. Proton Pump Inhibitors (PPI)
Omeprazole (Prilosec)
Ansoprazole (Prevacid)
Esomeprazole (Nexium)
Pantoprazole (Protonix)
Rabeprazole (Aciphex)

33. Pharmacologic Treatment of Acid/Peptic Disease
H2 Blockers
- cimetidine (Tagamet)
- famotidine (Pepcid)
- nizatidine (Axid)
- ranitidine (Zantac)

34. Protect stomach lining
Drugs used to protect stomach lining:
- sucrusulfate (Carafate)
- colloidal bismuths (Pepto Bismol)
- misoprostol/ Cytotec – contraindicated in pregnancy
*prostaglandin analog

35. Antibiotics used to treat H.Pylori
Tetracycline
Metronidazole (Flagyl)
Amoxicillin
Clarithromycin (Biaxin)

36. Pharmacologic Treatment of Acid/Peptic Disease
Colloidal bismuths have antimicrobial properties as well

37. Gastrointestinal Pharmacology
We will divide the disorders into groups:
- Acid/Peptic Diseases
- Vomiting
- Motility Disorders
- Inflammatory Bowel Disease
- Irritable Bowel Syndrome

38. Gastrointestinal Pharmacology
Drugs that prevent vomiting are called antiemetics. Many classes of drugs are used as antiemetics.

39. Antiemetics 5-HT3 antagonists – serotonin antagonists
D2 antagonists – antipsychotics
H1 antagonists – antihistamines
Antimuscurinics
Cannabinoids – active ingredient in marijuana

40. Antiemetics 5-HT3 antagonists - ondansetron (Zofran) D2 antagonists
- metoclopramide (Reglan)
- prochlorperazine (Compazine)
- promethazine (Phenergan)
- droperidol (Inapsine)

41. Antiemetics H1 antagonists - diphenhydramine (Benadryl)
- meclizine (Bonine)
Antimuscurinics
- scopolamine
- dimenhydrinate

42. Many H1 antagonists have anticholinergic, antimuscurinic properties, you will often see these cross listed

43. Antiemetics Cannabinoids are the active ingredient in marijuana:
- Dronabinal
- Nabilone

44. Motility Disorders Common motility disorders are:
- Gastroparesis – stomach weakness/stomach paralysis
- Neuropathy
- Diabetes mellitus
- Parkinsons, other neurologic disorders
Ileus
- postsurgical

45. Drugs used to treat motility disorders are also called prokinetics:
Cholinomimetics
- bethanecol – muscurinic agonist
- neostigmine – acetylcholinesterase inhibitor

46. Gastrointestinal Pharmacology
Drugs used to treat motility disorders are also called prokinetics.
- metoclopramide (Reglan)

47. Inflammatory Bowel Disease (IBD)
Inflammatory bowel disease disorders that cause the intestines to become inflamed (red and swollen). The inflammation lasts a long time and usually recurs

48. IBD
Symptoms include abdominal cramps and pain, diarrhea, weight loss and bleeding from the intestines

49. IBD There are two main forms of inflammatory bowel disease:
- Crohn’s disease
- ulcerative colitis

50. Pharmacology Treatment of IBD
Drugs used to treat inflammatory bowel disease are:
- immunosuppresive antimetabolites
- azathiorine
- 6 mercaptopurine
- methotrexate

51. Drugs used to treat IBD are:
Antitumor necrosis factor alpha
- infliximab (Remicade)

52. Drugs used to treat IBD are:
Aminosalicylates (prostaglandin inhibitor)
- mesalamine (Pentasa, Rowasa, Asacol)
- sulfasalazine (Azulfidine)

53. Do not confuse IBD – Inflammatory Bowel Disease - Crohn’s
- Ulcerative Colitis
IBS – Irritable Bowel Syndrome

54. IBS
Some people have constipation which means hard, difficult-to-pass, infrequent bowel movements. Often these people report straining and cramping when trying to have a bowel movement but cannot eliminate any stool

55. IBS
Some people with IBS experience diarrhea, which is frequent, loose, watery, stool. People with diarrhea frequently feel an urgent and uncontrollable need to have a bowel movement.

56. IBS
Most people with IBS alternate between constipation and diarrhea.

57. IBS
Sometimes people find that their symptoms subside for a few months and then return, while others report a consistent worsening of symptoms over time.

58. IBS STRESS is a contributing factor in IBS
IBS does not result in blood in stool

59. Pharmacologic Treatment of IBS
Drugs used to treat IBS include:
- 5-HT3 receptor antagonists
- alosetron (Lotronix)
- IBS with predominant diarrhea

60. Drugs used to treat IBS include
5-HT4 receptor antagonists
- tegaserod (Zelnorm)
- IBS with predominant constipation

61. Drugs used to treat IBS include:
Anticholinergics
- hyoscyamine (Levsin)