DH206: PHARMACOLOGY
CHAPTER 15 GI DRUGS
Lisa Mayo, RDH, BSDH
GI Drugs
HCl formation in stomach occurs in parietal cells
of the stomach (pH=1.0-2.0)
HCO3- leaves parietal cell
Cl- enter parietal cell & combo with H+ = HCl
Gastrointestinal Drugs
GI Diseases
1. Gastroesophageal reflux disease (GERD)
2. Peptic ulcer disease (PUD)
3. Chronic inflammatory bowel: Ulcerative colitis, Crohn’s
4. Constipation
5. Diarrhea
6. Nausea & Emesis(vomiting)
**The GI tract is highly susceptible to emotional changes
because it is innervated by the
VAGUS nerve associated with the ANS**
1. Gastroesophageal Reflux Disease
• GERD, or “heartburn,” is the most prevalent GI disease in U.S.
• Stomach contents flow back up into the esophagus through the
cardiac sphincter which is not functionally correctly
• Irritation, inflammation, erosion occur because esophagus not
designed to handle the levels of acids in the stomach
• Pain may be severe & felt in middle of chest
1. Gastroesophageal Reflux Disease
• Risk factors
• Alcohol use
• Smoking
• Spicy foods
• Stomach ulcers
• Meds: Aspirin, NSAIDs, CCB, Fosamax, Tetracycline
• Symptoms exacerbated by:
• Supine position
• Large meals
• Long-term complication = Barrett’s esophagus
1. Gastroesophageal Reflux Disease
Treatment
• Lifestyle changes
• Avoid eating for 4 hours prior to bed
• Eat smaller meals
• Pillow while sleeping
• Drugs therapy
1. Antacids
2. H2-antagonists
3. Proton-pump inhibitors (PPIs)
4. GI stimulants
2. Peptic Ulcer Disease (PUD)
• Peptic ulcer: circumscribed loss of tissue or break that
occurs in the GI mucosa extending through the smooth
muscle that lines the GI tract
• Occurs when imbalance of:
1. Gastric acid
2. Pepsin
3. Mucosal defense factors prostaglandins
• Dental Management: p.187, Box 15-1
• Etiology
1. Helicobacter pylori (gram (-) & alters inflammatory
response)
• Combo Tx of 2 ABX + H2-blocker/PPI
2. Long-term aspirin/NSAID or corticosteroid use
2. Treatment PUD
1. Same as GERD plus:
2. Prostaglandins
3. Protective barriers
4. ABX: H.pylori
NBQ
Which of the following risk factors are primarily involved in
causing peptic ulcer disease?
a. Smoking & alcohol
b. Caffeine & smoking
c. H.pylori and NSAIDs
d. S.mutans and alcohol
NBQ
Which of the following risk factors are primarily involved in
causing peptic ulcer disease?
a. Smoking & alcohol
b. Caffeine & smoking
c. H.pylori and NSAIDs
d. S.mutans and alcohol
3. Chronic Inflammatory Bowel Disease (IBD)
2 categories of inflammation
1) Ulcerative colitis: sores in mucosal of colon/rectum
2) Crohn’s Disease: inflammation spreads deep into
affected tissues
• Smoking cessation may exacerbate
3. Chronic Inflammatory Bowel Disease (IBD)
DRUGS FOR TX
FIBER SUPPLEMENTS 1st
ANTIINFLAMMATORY
Sulfasalzine(Azulfidine)
Mesalamine(Apriso)
Balsalazide(Colazal)
Olsalazine(Dipentum)
CORTICOSTEROIDS
Prednisone
IMMUNOSUPPRESSANT
6-mercaptopurine(Purinethol)
Azathioprine(Imuran)
Cyclosporine
ANTIDIARRHEAL
Imodium
ANTISPASMODICS
Anticholinergics
TNF-ALPHA NUETRALIZER
Infliximab(Remicade)
4. Constipation
Risk factors
1) Narcotics
2) Anticholinergics
3) CCB
4) Aluminum-containing antacids
5) Iron products
p.190
Agents
Drugs
Bulk-forming laxatives
Methycellulose, polycarbophil, psyllium
Watery evacuation
(osmotic/saline laxative)
Magnesium
Lubricant
Mineral oil
Soften stool/Emollients
Disacodyl sodium sulfosuccinate
5. Diarrhea
Etiology
• Most common bacterial causes: Salmonella, E.coli
• ABX: broad-spectrum most common
• NSAIDs, Diuretics, Antihistamines (H2-inhibitors), Digoxin
DRUGS
NOTATIONS
Ioperamide(Imodium)
Diphenoxylate + Atropine
(Lomotil)
Opiate + Anticholinergic
Bismuth
subsalicylate(Pepto-Bismol,
Keopectate)
Traveler’s diarrhea (NBQ)
Yogurt or acidophilus
Use when on broad-spectrum ABX
Yogurt 2hrs before tetracycline (NBQ)
NBQ
All of the following drugs reduce GI motility and are used to treat
diarrhea EXCEPT which one?
a. Loperamide(Imodium)
b. Bismuth subsalicylate(Pepto-Bismol)
c. Furosemide(Lasix)
d. Diphenoxylate and atropine(Lomotil)
e. Attapulgite(Kaopectate)
NBQ
All of the following drugs reduce GI motility and are used to treat
diarrhea EXCEPT which one?
a. Loperamide(Imodium)
b. Bismuth subsalicylate(Pepto-Bismol)
c. Furosemide(Lasix) Loop diuretic for HBP
d. Diphenoxylate and atropine(Lomotil)
e. Attapulgite(Kaopectate)
NBQ
Which of the following drugs has the potential to cause severe
diarrhea?
a. Clindamycin
b. Ciaspride
c. Diazepam
d. Metronidazole
e. Vancomycin
NBQ
Which of the following drugs has the potential to cause severe
diarrhea?
a. Clindamycin
b. Ciaspride
c. Diazepam
d. Metronidazole
e. Vancomycin
6. Nausea & Emesis
• NO Clindy
• Drugs used to tx
1)
2)
3)
4)
Anticholinergic
Antiemetic
Depress chemoreceptor trigger zone
Cannabinoids
DRUG CLASS
DRUGS
Phenothiazide
Phenergan, Compazine
Anticholinergic
Dramamine, Bonine
Block chemoreceptor trigger zone
Zofran, Anzemet, Tigan
I Promise I Won’t Do This to You!!!
Drugs Used to Treat GI Diseases
Acid Neutralizers
1. Antacids
Antisecretory Drugs: Receptor-Mediated Drug Action
1. Antihistamines (H2-blocking agents)
2. PPIs
3. Prostaglandins
4. GI stimulants
Protective Barrier Drugs
1. Sucralfate(Carafacte)
Drugs Used to Treat GI Diseases
Acid Neutralizers
1. Antacids
Antisecretory Drugs: Receptor-Mediated Drug Action
1. Antihistamines (H2-blocking agents)
2. PPIs
3. Prostaglandins
4. GI stimulants
Protective Barrier Drugs
1. Sucralfate(Carafacte)
Acid Neutralizers
P.189
Antacids
 Used to relieve the pain & indigestion
 Many brands OTC: magnesium, aluminum, calcium
 Oldest antacid: sodium bicarb (Alka-Seltzer) but can create
alkalosis, cannot be used by cardiac patients
 Pepto-Bismol: used in tx PUD
Acid Neutralizers
Antacid
Use
Calcium carbonate(Tums, Maalox)
GERD
Magnesium hydroxide(Milk of Magnesium)
GERD
Aluminum/magensium hydroxide/simethicone(Maalox, Mylanta) GERD
Calcium carbonate/magensium hydroxide(Rolaids)
GERD
Sodium bicarbonate (Gaviscon)
GERD
Bismuth subsalicylate(Pepto-Bismol)
PUD
H.pylori
Acid Neutralizers
Antacids
 Action:
Basic salts
Neutralize HCl acids in stomach
Raise pH of stomach
 Can alter absorption of MANY other drugs
 Short duration (30min)
Guidelines for Patients
Antacids taken 2hrs prior to tetracycline (CH7)
Hypertensive pt’s: avoid sodium-based antacids
NBQ
Which of the following GI drugs should not be given concurrently
with doxycycline?
a. Omeprazole
b. Cimetidine
c. Antacids
d. Lansoprazole
NBQ
Which of the following GI drugs should not be given concurrently
with doxycycline?
a. Omeprazole
b. Cimetidine
c. Antacids
d. Lansoprazole
Drugs Used to Treat GI Diseases
Acid Neutralizers
1. Antacids
Antisecretory Drugs: Receptor-Mediated Drug Action
1. Antihistamines (H2-blocking agents)
2. PPIs
3. Prostaglandins
4. GI stimulants
Protective Barrier Drugs
1. Sucralfate(Carafacte)
Drugs Used to Treat GI Diseases
Antisecretory Drugs: Receptor-Mediated Drug Action
1. Antihistamines (H2-blocking agents)
P-450 inhibitors –
MANY drug
2. PPIs
interactions
3. Prostaglandins: Misoprostol
4. GI stimulants: Metoclopramide
Parietal cell are the site of action of
Antihistamines, PPI, Prostaglandins
Drugs Used to Treat GI Diseases
Antisecretory Drugs: Receptor-Mediated Drug Action
1. H2-blocking agents
Histamine Review
Histamine located in GI mucosa within mast cells
Histamine Receptors (called H2-receptors)
Mediate secretion of gastric acid & pepsin
Located in parietal cells of the GI system (parietal cells
produce acids)
H2 stimulation = parietal cells release more acids (↓pH)
If block receptors: reduce acid & pepsin production
Parietal cells
(secrete
histamine)
Site of action of
antihistamines
↓
Reduce acid &
pepsin production
Drugs Used to Treat GI Diseases
Antisecretory Drugs: Receptor-Mediated Drug Action
1. Antihistamines
• Inhibit P-450 – interact with MANY drugs (NBQ)
• Similar onset of action to antacids (quick) but longer duration of
action
All end in ~tidine
• Uses: PUD & GERD
Antihistamines
cimetidine(Tagamet)
PROTYPE
Ranitidine(Zantac)
Famotidine (Pepcid, Mylanta AR)
Nizatidine(Axid)
Drug interactions due to CYP1A2 liver
metabolism
Do NOT use more than 6wks
(agranulocytosis, diarrhea)
Drugs Used to Treat GI Diseases
Antisecretory Drugs: Receptor-Mediated Drug Action
2. PPIs
• Drug of choice for patients with daily symptoms or those not
responding to antihistamines
• Reduce peak acid output
• Achieve almost total suppression of acid secretion because they
bind irreversibly to parietal cells
• Many drug interactions (P-450 inhibition) (NBQ)
Guidelines for Patients
Valium & Dilantin interactions
No aspirin
Xerostomia
Drugs Used to Treat GI Diseases
Antisecretory Drugs: Receptor-Mediated Drug Action
PPIs
PPIs
Omeprazole(Prilosec)
Omeprazole/sodium bicarbonate(Zegerid)
Lansoprazole(Prevacid)
Esomeprazole(Nexium)
Rabeprazole(AcipHex)
Pantoprazole(Protonix)
Rabeprazole(AcipHex)
PROTYPE
Drugs Used to Treat GI Diseases
Antisecretory Drugs: Receptor-Mediated Drug Action
3.
Prostaglandins: Misoprostol(Cytotec)
p.189
• Synthetic prostaglandin (PGE2α)
• Management of NSAID/Aspirin-induced ulcers
• Inhibits gastric acid secretions
• Increases gastric mucosal defenses
• Pregnancy category X
Drugs Used to Treat GI Diseases
Antisecretory Drugs: Receptor-Mediated Drug Action
4. GI stimulants: Metoclopramide(Reglan)
• Stimulates contraction of the lower esophageal sphincter by
enhancing action of ACH (acetylcholine)
↓
• Decrease reflex gastric juices back into esophagus
• GERD ONLY, not PUD
NBQ
Which 3 GI drugs below reduce the formation of stomach acid by
inhibiting the proton pump of the stomach parietal cells?
a. Ranitidine(Zantac)
b. Esomeprazole(Nexium)
c. Famotidine(Pepcid)
d. Omeprazole(Prilosec)
e. Lansoprazole(Prevacid)
NBQ
Which 3 GI drugs below reduce the formation of stomach acid by
inhibiting the proton pump of the stomach parietal cells?
a. Ranitidine(Zantac)
b. Esomeprazole(Nexium)
c. Famotidine(Pepcid)
d. Omeprazole(Prilosec)
e. Lansoprazole(Prevacid)
Drugs Used to Treat GI Diseases
Acid Neutralizers
1. Antacids
Antisecretory Drugs: Receptor-Mediated Drug Action
1. Antihistamines (H2-blocking agents)
2. PPIs
3. Prostaglandins
4. GI stimulants
Protective Barrier Drugs
1. Sucralfate(Carafacte)
Barrier Enhancer
Sucralfate(Carafate)
• Complex of aluminum hydroxide + sulfated sucrose
• “Bandage” over ulcer
• PUD short-term tx
• Forms a protective barrier over damaged mucosa, binds to
PRO in ulcers
• Inhibits the action of pepsin
• Absorbs bile salts that can cause irritation of the gastric
lining
• Most common side effect: constipation
Summary Tx for PUD/GERD
PUD TX
2 ABX + Antihistamine + Antacid
GERD TX
Antacid + Antihistamine/PPI
NBQ
Which of the following drugs is best for starting initial treatment
of mild, intermittent heartburn?
a. Sodium bicarbonate/alginic combination
b. Cimetidine
c. Omeprazole
d. Lansoprazole
NBQ
Which of the following drugs is best for starting initial treatment
of mild, intermittent heartburn?
a. Sodium bicarbonate/alginic combination
b. Cimetidine
c. Omeprazole
d. Lansoprazole