This document discusses drugs that act on the digestive system, specifically those used to treat conditions related to acid production and motility in the gastrointestinal tract. It covers antacids, H2 receptor blockers, and proton pump inhibitors which are used to reduce acid in conditions like GERD and peptic ulcers. It also discusses laxatives and antidiarrheal drugs used to treat constipation and diarrhea respectively. Finally, it outlines the pathways of vomiting and the sites of action of various antiemetic drugs like antihistamines, anticholinergics, and serotonin blockers.

1. DRUGS IN MODERN MEDICINE
ACTING ON DIGESTIVE SYSTEM
Dept of Dravyagunavijnan,
RGAMC

2. Acid-related Pathophysiology
 Hydrochloric acid (HCL) aids in digestion and
serves as a barrier to infection.
 Pepsinogen is an enzyme that digests dietary
protein.
 Mucous protects the lining of the stomach
from both HCL and digestive enzymes.
 Prostaglandins has an anti-inflammatory and
protective function.

3. GIT DISORDERS
 Oral cavity
 Esophagus
 Liver
 Stomach
 Small intestine
 Large intestine
 Pancreas
 Gallbladder
 Stomatitis
 GERD
 Hepatitis, cirrhosis
 Peptic ulcer, Gastritis
 Malabsorption,
inflammatory bowel
 Diarrhoea, constiation
 Pancreatitis, diabetes
 Cholesystitis,
cholelithiasis

4. Antacids
 Are basic compounds used to neutralize
stomach acid.

5. OTC Products
 Antacids were the most common products
used for acid-indigestion until the 1970’s
when histamine-2 (H2 antagonists) were
developed.

6. Action
 Primary drug effect of antacids is the
reduction of symptoms associated with acid-
related disorders: pain and reflux (heartburn)
 Raises gastric pH from 1.3 to 1.6.

7. Indications
 Acute relief of symptoms associated with:
 peptic ulcer disease (PUD)
 Gastritis
 gastric hyperacidity
 Heartburn or gastro esophageal reflux (GEF)

8. GERD
- Backflow of stomach acid into the
esophagus
- Esophagus is not equipped to handle
stomach acid => scaring
- Usual symptom is heartburn, an
uncomfortable burning sensation behind
the breastbone (MI often mistaken for
GERD !)

9. GERD
- More severe symptoms: difficulty swallowing,
chest pain
- Reflux into the throat can cause sore throat
- Complications include esophageal erosions,
esophageal ulcer and narrowing of the
esophagus (esophageal stricture) In some
patients (~10%), the normal esophageal lining or
epithelium may be replaced with abnormal
(Barrett's) epithelium. This condition (Barrett's
esophagus) has been linked to cancer of the
esophagus.

10. Gastroesophageal Reflux Disease
(GERD)
Endoscope of Barrett’s Esophagus
(can become malignant - needs monitoring)

11. Peptic Ulcer Disease
 Ulcer formation in the esophagus, stomach or
duodenum
 Mucous exposed to gastric acid and pepsin
 Imbalance between cell-destructive and cell-
protective effects
 Gastric acid and pepsin
 H. pylori – infectious process

12. Peptic Ulcer Disease

13. Treatment of Heartburn, GERD and PUD
Antacids
H2 Receptor Blockers
Mucosal Protective Agents
Proton Pump Inhibitors
Anti-cholinergics
Prostaglandin Analogs
Anti-microbial Agents

14. Adverse Effects
 Magnesium preparations especially milk of
magnesium or MOM can cause diarrhea.
 Calcium products can cause kidney stones.
 Sodium bicarbonate products can cause
systemic alkalosis.
 Self-treatment can result in masking
symptoms of a disease (bleeding ulcer or
stomach cancer).

15. Contraindications
 Allergy to the drug
 Severe renal failure
 Electrolyte disturbances
 Gastro intestinal obstruction

16. Interaction
 May effect absorption of other drugs.
 Chemically inactivates certain drugs
 Increased stomach pH decreasing absorption
of acidic drugs

17. OTC Preparations
 Magnesium-containing antacids
 Gaviscon Liquid, Milk of Magnesium
 Aluminum-containing antacids
 Amphogel, Maalox
 Sodium-containing antacids
 Alka-seltzer, Tums

18. Gelusil / Mylanta

19. H 2 Antagonists
 H2 receptor blockers
 cimetadine (Tagamet),
 ranitidine (Zantac)
 famotidine (Pepcid)
 nizatidine (Axid)

20.  Action:
 blocks the H2 receptor of acid-producing parietal
cells
 Reduce hydrogen ion secretions to increase pH of
stomach
H2 antagonists

21. Therapeutic Uses
 GERD or gastro-esophageal reflux
 PUD or peptic ulcer disease
 Zollinger-Ellison Syndrome (excessive gastric
acidity)

22. Adverse Effects
 Overall very low incidence of adverse effects
 May cause some CNS effects in the geriatric
patient.
 Smoking reduces effectiveness
 H2 antagonist should be taken 1 hours before
taking any antacids

23. Proton Pump Inhibitors
 Newest drugs used in the treatment of acid-
related disorders.
 lansopraxole (Prevacid)
 omeprazole (Prilosec)
 rabeprzole (Acephex)
 pantoprazole (Protonix)
 exomepraxole (Nexium)

24. PPIs
 Action: Binds directly to the hydrogen-
potassium - ATPase pump mechanism,
inhibiting the action of the enzyme which
results in a total blockage of hydrogen ion
secretion from the parietal cells.

25. Adverse Effects
 Long term use might promote malignant
gastric tumors.
 Concern about over prescribing resulting in
reduction of normal acid-mediated
antimicrobial protection.
 May need a probiotic when using PPI drug
therapy.

26. Probiotics
 Probiotics are live microorganisms (in most
cases, bacteria) that are similar to beneficial
microorganisms found in the human gut.
They are also called "friendly bacteria" or
"good bacteria." Probiotics are available to
consumers mainly in the form of dietary
supplements and foods. They can be used as
complementary and alternative medicine.

27. Helicobacter pylori
H. pylori are bacteria able to attach to the epithelial cells of the stomach
and duodenum which stops them from being washed out of the stomach.
Once attached, the bacteria start to cause damage
to the cells by secreting degradative enzymes,
toxins and initiating a self-destructive immune
response. www.science.org.au/ nobel/2005/images/invasion.jpg

28. Anti-H.pylori Therapy
Triple Therapy - 7 day treatment - Effective 80-85%
Proton pump inhibitor + amoxicillin/tetracycline + metronidazone/clarithomycin
Quadruple Therapy - 3 day treatment, as efficacious as triple therapy
- Add Bismuth to triple therapy
• >85% PUD caused by H. pylori
• Antibiotic Ulcer Therapy - Used in Combinations
• Bismuth - Disrupts bacterial cell wall
• Clarithromycin - Inhibits protein systhesis
• Amoxicillin - Disrupts cell wall
• Tetracycline - Inhibits protein synthesis
• Metronidazone - Used often due to bacterial resistance to
amoxicillin and tetracycline, or due to intolerance

29. Antidiarrheals and Laxatives

30. Diarrhea•Caused by:
•Toxins
•Microorganims (shigella, salmonella, E.coli,
campylobacter, clostridium difficile)
•Antibiotic associated colitis
•Indications for treatment
•>2-3 days
•Severe diarrhea in the elderly or small children
•Chronic inflammatory disease
•When the specific cause has been determined

31. Anti-Diarrheal Agents
•Anti-motility Agents
•Reduce peristalsis by stimulating opioid
receptors in the bowel
•Allow time for more water to be absorbed by the
gut
•Morphine
•Codeine
•Diphenoxylate
•Loperamide
•Contraindications for antidiarrheals
•Toxic Materials
•Microorganisms (salmonella, E.coli)
•Antibiotic associated
Loperamide

32. Antidiarrheal Drugs
 Used to treat diarrhea.
 Adsorbents
 Antimotility (anticholenergic and opiates)
 Intestinal flora modifiers or bacterial replacement
drugs

33. Adsorbents
 Act by coating the walls of the GI tract.
 Bind with the causative bacteria or toxin to
their adsorbent surface for elimination
through the stool.

34. Pepto-Bismul and Kaoectate
 Generic: bismuth subsalicylate
 Same chemical structure as salicylate
 use with caution in children. May cause Reyes
Syndrome
 Use with caution in clients who are on anti-
coagulation therapy.

35. FDA Warning
 The main ingredient, bismuth subsalicylate,
has been linked with Reye Syndrome, a
potentially life-threatening disorder that has
been associated with kids that have viral
illnesses, especially the flu and chicken pox,
and who take aspirin and other salicylate
containing medications, like Pepto-Bismol.
 Label advises not to give to children under
age 12 years.

36. Anticholinergics
 Used either alone or in combination with
other antidiarrheal drugs.
 Acts by slowing GI tract motility
 Atropine
 hyoscyamine
 hyoscine

37. Opiates
 Products containing Codeine
 Nursing consideration: clients on opioids for
post-operative pain control may suffer from
constipation.
 Atropine: often used to control secretions
during surgical procedure – may contribute to
post-operative constipation

38. Imodium A D
 Generic name: loperamide
 Classification: Opiate antidiarrheal
 Action: inhibits both peristalsis in the intestine
and intestinal secretions, decreasing the
number of stools and their water content.
 Contraindications: ulcerative colitis, acute
diarrhea due to E-coli (Escherichia coli)

39. Clostridium Difficile -THE MAJOR CAUSE
OF DIARRHOEA IN ANTIBIOTIC USERS•Three steps to infection
•Alteration of normal fecal flora
•Colonic colonization of C. difficile
•Growth and production of toxins
•Infection can lead to formation of colitis and toxic megacolon
•Pharmacological Treatment
• Discontinue offending antibiotic
• Metronidazole (contraindicated in patients with liver or renal
impairment)
• Vancomycin (contraindicated in patients with renal impairment)

40. Constipation
 Definition: abnormally infrequent and difficult
passage of feces.
 Constipation is a symptom not a disease.

41. Laxatives
 Laxative act by:
 Affecting the consistency of the stool
 Increasing fecal movement through the colon
 Facilitating movement through the colon

42. Laxatives

43. Bulk-forming Laxatives
 Composed of water-retaining natural and
synthetic cellulose derivates.
 Psylium is an example of natural bulk-forming
laxative.
 Methylcellulose is an example of a synthetic
cellulose derivative.

44. Bulk-forming Laxative
 Action: increases water absorption, which
results in greater bulk of the intestinal
contents.
 Tend to produce normal, formed stools.
 Action limited to GI tract so adverse effects
are minimal.

45. Citrucel (methylcellulose)

46. Emollient laxative
 Generic classification: docusate salts
 Trade names: Colace, Surfak
 Action: work by lowering the surface tension
of GI fluids; more water and fat are absorbed
into the stool and intestine.

47. Emollients
 Uses:
 post partum
 postoperative patients
 Clients on long-term pain control
 Outcomes: soft stool with easier defecation

48. Hyperosmotic Laxatives
 Glycerine
 Action: promotes bowel movement by
increasing the osmotic pressure in the
intestine.
 Note: given in the form of a suppository

49. Stimulant Laxatives
 Through the use of natural plant products and
synthetic chemical drugs induces intestinal
peristalsis.
 Note: the stimulant class is the most likely to
cause dependence.

50. Stimulant Laxatives
 Generic: senna
 Trade: Senokot
 Action: stimulates the GI tract
 Adverse effects: may cause abdominal pain.
 Onset of action: complete bowel evacuation
in 6 to 12 hours.

51. Laxative Abuse
•Most common cause of constipation!
•Longer interval needed to refill colon is misinterpreted
as constipation
=> repeated use
•Enteral loss of water and salts causes release of
aldosterone
=> stimulates reabsorption in intestine, but
increases renal excretion of K+
=> double loss of K+ causes hypokalemia,
which in turn reduces peristalsis.
=>This is then often misinterpreted as
constipation
=> repeated laxative use

52. Antiflatulants
•Used to relieve the painful symptoms associated with gas
•Simethicone (a detergent)
•Alters elasticity of mucus-coated bubbles, causing them to
break
•Large bubbles -> smaller bubbles, and less pain
•Used often, but limited data regarding effectiveness
Simethicone

53. Anti emetic drugs

54. Emesis
(motion sickness)
(seeing something repulsive)
(Ingesting a toxin)

55. Chemoreceptor Trigger Zone (CTZ)
 The area of the brain that is involved in the
sensation of nausea and the action of
vomiting.

56. Vomiting Center (VT)
 The area of the brain that is involved in
stimulating the physiologic events that lead to
nausea and vomiting.

57. Antiemetic Drugs
 Drugs used to relieve nausea and vomiting.
 All emetic drugs work at some site in the
vomiting pathways.

58. Syrup of Ipecac
 AAP recommendations in 2003 issued an
alert to stop the use of this drug to induce
vomiting after drug overdose.

59. Anticholinergic Drugs
 Act by binding to and blocking acetylcholine
receptors (ACh) in the vestibular nuclei,
located deep in the brain.
 One drug scopolamine
 Most commonly used drug for treatment and
prevention of nausea and vomiting
associated with motion sickness and
postoperatively.

60. Antihistamines
 Action: binds to H1 receptors, potentiate
anticholinergic activity.
 Most popular OTC medications
 Generic name: dimenhydrinate
 Trade name: Dramamine and Benadryl
 OTC drugs used for motion sickness

61. Neuroleptics
 Action: antidopaminergic, antihistamine and
anticholinergic properties.
 Trade names: Compazine, Thorazine,
Phenergan
 Often given as preoperative medication.
 Used to treat psychotic disorders due to
effect on dopamine.

62. Serotonin Blockers
 Called 5-HT3 receptor blockers because they
block the 5-HT3 receptors in the GI tract,
CTZ and vomiting centers VC.

63. Antiemetic Therapeutic Sites -
SummaryCancer Chemotherapy Drugs
Dopamine agonists
Ondansetron
Phenothiazines
Scopolamine
H1 Antihistamines
Ondansetron
All
Chemoreceptor
Trigger Zone
(CTZ)