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99 Cards in this Set

  • Front
  • Back
What 2 things do GI drugs usually correct disorders of?
1. Secretion

2. Motility
What is the most common secretory disorder of the GI?
Acid-peptic disease:
1. Peptic ulcer disease
3. other hypersecretory states (Z-E syndrome)
What are the 3 aims of drug treatment for Acid-peptic disease?
1. releive pain

2. promote healing

3. prevent recurrence
What do motility disorders include?


Neural pathway regulating Gastric Acid secretion: Neural
1. Mediator
2. Receptors
3. Antagonist
1. Acetycholine
2. Muscarinic
3. Anti-muscarinic
Neural pathway regulating Gastric Acid secretion: Endocrine
1. Mediator
2. Receptors
3. Antagonist
1. Gastrin
2. Gastrin / CCK-B
3. H2 blocker
Neural pathway regulating Gastric Acid secretion: Paracrine
1. Mediator
2. Receptors
3. Antagonist
1. Histamine
2. H2
3. H2 blocker
What 3 things does Gastrin stimulate?
1. Gastric motility
2. HCl secretion
3. Pepsin secretion
T or F: there are no Gastrin antagonists?
What are the actions of Histamine on the GI?
1. H2 receptors -> activate Adenylyl Cyclase -> increased cAMP -> activates proton pump -> increased Gastric Acid secretion

2. enhances Parietal Cell affinity for both Gastrin and ACh
Why are Anti-muscarinic drugs relatively weak inhibitors of acid secretion?
b/c they act at only one receptor site

**Acid secretion can therefore be stimulated by Gastrin & Histamine
When & how are Anti-muscarinic drugs used to treat Gastric Acid treatment?
Used as adjuncts to H2 blockers especially in patients that respond poorly to H2 blockers
Describe Gastric Acid secretion in terms of Enterchromaffin-like cells, Parietal cells, their mediators, and their receptors
1. ECL cells are stimulated by Gastrin & ACh to secrete Histamine

2. Parietal Cells have Gastrin, Muscarinic, & H2 receptors -> activate AC -> increased cAMP

3. cAMP -> activates Protein Kinases -> stimulate Acid secretion by ATPase proton pump (which is final common pathway)
What are the most poweful drugs for inhibiting gastric acid secretion?
Proton pump inhibitors = "-prazoles"

**blocks the final common pathway for acid secretion
Therapeutic goal of Drug treatment for Acid-peptic disease:
1. Proton pump inhibitors
2. H2-antagonists
3. Antacids
4. Mucosal protective agents
5. Antimicrobial
1. inhibit gastric acid secretion
2. inhibit gastric acid secretion
3. Neutralize gastric acid
4. Acid barrier in necrotic tissue
5. eradicate H. pylori
What is the common ending for the Proton Pump Inhibitors?

What does a single daily dose of PPI's provide?
-inhibits Gastric acid secretion by 95-100%

-does NOT affect Pepsin secretion or Gastric Motility
How long does Gastric Acid inhibition persist after PPI withdrawal? Why
4-5 days b/c that is the amount of time need to synthesize new proton pumps (H+/K+ ATPase)
List 3 most common side effects of PPI's
1. GI effects = nausea, colic, flatulence, constipation, diarrhea

2. CNS effects = headache, dizziness, somnolence

3. Skin rashes
What are 2 side effects that may occur with prolonged use of PPI's
1. Diarrhea due to GI bacterial overgrowth from removal of natural acid barrier

2. Hyper-gastrin-emia
How are PPI's cleared from the body?
Hepatic metabolism w/ neglible renal clearance
What type of compounds are PPI's?

What is their mechanism of action?

IRREVERSIBLE inhibit the Parietal Cell proton pump, H+/K+ ATPase
PPI's are __1__ that are inactive at __2__ pH
1. prodrugs

2. neutral
Activation of PPI's requires what type of environment? What should they be taken with...why?
Acidic environment

Meals so that food can stimulate acid secretion
B/c PPI's are unstable at a low pH, what is done to avoid degradation by acid in the esophagus and stomach?
Dosage forms are supplied as Enteric Coated Granules that dissove only at Alkaline pH
After PPI's pass through the stomach, the __1__ dissolve and the PRODRUG is absorbed in the __2__

Progdrug is then carried by the __3__ to the Parietal cells where it accumulates in the secretory canaliculi to be activated at __4__ pH and form __5__ which then binds to __6__ groups on the H+/K+ ATPase
1. enteric coating
2. Intestines
3. circulation
4. acid
5. Sulfonamide or Sulfenic acid
6. Sulfhydryl
Intestinal absorption of PPI's is rapid, but what does the bioavailability of the absorbed form depend on?
activation at Gastric Acid pH
What 2 things do PPI's promote?

PPI's are often effective in patients unresponsive to _____

PPI's are more effective than H2-antagonists for ______ & _____
Peptic ulcer healing & prevent ulcer recurrence


GERD or NSAID-induced peptic ulcers
What is the common ending for the H2-receptor Antagonists?

H2-receptor antagonists are all __1__ preparations that inhibit acid secretion for < __2__ hours
1. OTC

2. 6
H2-antagonists are structural analogs of __1__ that block H2 receptors selective to reduce __2__ & __3__ secretion without affecting H+/K+ ATPase, H1 or any other receptors
1. Histamine

2. Gastric acid
3. Pepsin
GI drug that is especially effective against NOCTURNAL secretion of Gastric Acid
H2-antagonists (-tidine's)

**nocturnal secretion is largely due to Histamine
**Acid is reduced by 90% at night as compared with 60-80% during day
List the relative potentcy of the 4 H2-antagonists
Famo > Niza = Rani > Cime

**all end in -tidine
**are all equally effective, rapidly and well absorbed orally, and generally well tolerated with few side effects
To what people should H2-antagonists not be given to?
Pregnant or nursing women b/c they cross the placenta and are secreted into Breast milk
What are the most common side effects of the -tidine's?
Mental changes like confusion, hallucination, and agitation may occur with __1__ administration of "-tidine's" in patients who are __2__ or who have __3__
1. IV

2. Elderly
3. Renal or Hepatic dysfunction
GI drug that may cause Gynecomastia or Impotence in men; Galactorrhea in women

Why does it do this?

inhibits binding of Dihydrotestosterone to androgen receptors, inhibits estradiol metabolism, and increases serum prolactin
GI drug that interferes with Cytochrome P450 pathways for Hepatic metabolism of many drugs including warfarin, theophylline, phenytoin, lidocaine, quinidine, propranolol, labetalol, metoprolol, tricyclic antidepressants, benzodiazepines, calcium channel antagonists, sulfonylureas, metronidazole, and ethanol

**listed drugs will not be metabolized if Cimetidine is co-taken
All H2-antagonists (-tidine's) are equally effective for these 2 things
Healing & preventing recurrence of Peptic Ulcer Disease
GI drug given once daily at bedtime to suppress nocturnal acid secretion & will produce ulcer healing rates of > 80-90% after 6-8 wks of treatment
-tidine's = H2 antagonists
For what 2 reasons has the use of H2-antagonists markedly declined?
Discovery of PPI's

Discovery of role of H. pylori in PUD
H2-antagonists have a 20% failure rate in these 2 groups of ulcer patients
1. Smokers

2. Elderly
Why should H2-antagonists not be used in conjunction with PPI's?
H2-antagonists reduce the efficacy of PPI's by reducing their acid activation
H2-antagonists are combined with these 2 things for treatment of patients with H. pylori infection
1. Antibiotics

2. Bismuth
List the 3 preparations of Antacids
1. Aluminum hydroxide

2. Calcium carbonate

3. Aluminum hydroxide + Magnesium hydroxide
What is the most common side effect of Aluminum hydroxide?

**aluMINIMUM amount of feces
What is the most common side effect of Magnesium hydroxide?

**Mg = Must Go to the bathroom
What is the general use of Antacids?
PRN ("as the situation arises") to relieve pain in Esophagitis, Peptic ulcer, and GERD
What is the mechanism of action of Antacids?
Are weak bases that neutralize Gastric HCl to form salt & water

**may interfere with the absorption of other drugs
Aside from neutralizing Gastric HCl, what other function may Antacids provide?
Mucosal protection by stimulating PG synthesis
Binds selectively to necrotic ulcer tissue and acts as a barrier

**"Sucks" to the ulcer site
Mucosal protective agent that requires acid pH for activation and should not be given together with Antacids, H2-antagonists, or PPI's
What is the mechanism of action of Sucralfate
1. Polymerizes to produce a viscous, sticky gell that adheres strongly to epithelial cells and ulcer craters in acid environment

2. effective in healing Duodenal ulcers
What is the most common adverse effect of Sucralfate?
Methyl analog of PGE1 that binds to PG receptors on Parietal cells to inhibit acid secretion
What is Misoprostol used specifically to prevent? Why?
NSAID-induced ulcers

b/c NSAID's inhibit PG formation; Misoprostol is a PG analog
What are the 2 most frequent side-effects of Misoprostol?

Abdominal pain
2 mechanisms of Misoprostol
1. PGE1 analog thtat increases production and secretion of Gastric MUCUS BARRIER

2. Decreases acid production by inhibiting Histamine-stimulated gastric secretion
Binds selectively to ulcers and provides protective coating; may also be antibacterial against H. pylori
Bismuth subsalicylate = Pepto-Bismol
What are the adverse effects of Bismuth?
Darken the tongue and stools b/c the Bismuth Sulfide formed is a black solid
What is the best regimen of treatment for H. pylori infection?
10-14 day "triple therapy" treatment:

1. Clarithromycin
2. Amoxicillin
3. PPI

**pts allergic to Penicillin, use Metronidazole instead of Amoxicillin
What should a normal stool frequency be in Western culture?
at least 3 times per week
What people most commonly suffer from constipation?
Women & Elderly
Drugs used to promote defecation & treat constipation are reffered to as:
laxative = cathartic = purgative = aperient =evacuant
Why are Laxatives usually unnecessary?
Constipation can usually be resolved by:
1. increasing water and fiber content of diet
2. appropriate bowel habits and training
3. improved physical activity & exercise
4. attention to psychosocial & emotional factors
List the 3 Osmotically Active Laxatives
1. Saline laxatives

2. Nondigestible sugars and alcohols

3. Polyethylene Glycol (PEG)-electrolyte solutions
Nonabsorbable salts containing Magnesium cations or Phosphate anions
Saline laxatives
Mechanism of action of Saline Laxatives
Salts act by osmotic force to hold water inside intestines ➡ distened intestines ➡ stimulate peristalsis
Laxatives that have an extremely bitter taste that is masked by adding citrus juices
Saline Laxatives
Under what conditions should Saline Laxatives be avoided?
1. Renal insufficiency

2. Heart Disease

3. Electrolyte imbalance

4. being treated with Diuretic drugs
Trihydroxy alcohol that when given rectally acts as a lubricant and hygroscopic agent ➡ water retention ➡ stimulate peristalsis
3 nonabsorbable sugars ➡ hydrolyzed to organic acids ➡ acidify luminal contents ➡ draw water into lumen ➡ increase colonic propulsive motility


What is in a Polyethylene glycol (PEG)-electrolyte solution?
1. Sodium sulfate
2. Sodium bicarbonate
3. Sodium chloride
4. Potassium chloride
5. Isotonic solution containing 60 g of Polyethylene glycol per L
Laxative used to prepare for colonoscopy: drink 3-4 liters over 3-4 hrs to produce water diarrhea and remove solid wastes
Polyethylene glycol (PEG)-electrolyte solution
Describe the mechanism of action of Stimulant or Irritant Laxatives
1. act directly on Enterocytes, Enteric neurons, and muscle
2. induce low-grade intestinal inflammation
3. water and electrolytes accumulate
4. increased intestinal motility
Diphenylmethane derivative that is available as enteric coated tablets taken at bedtime to take effect the next morning (causes you to poop)

**to avoid activation in the stomach (causes gastric irritation & cramping) tablets should be swallowed w/out chewing or crushing

**"B is a code" that you take at night & you wake up to go poop
3 Anthraquinones that are poorly absorbed in the small intestine and require activation in the colon with laxative effect 6-12 hrs later

Cascara sagrada

Longterm usage of this Laxative causes Melanomic pigmentation of colon mucosa and "cathartic colon" (colon becomes dilated and ahaustral)
-Cascara sagrada
Castor oil that is a local irritant that increases intestinal secretion and motility; now seldom used due to unpleasant taste and toxic potential
Rici-noleic acid

**Rice crispies with Castor Oil will run right thru you
List 3 stool softners
1. Mineral oil

2. Glycerin suppositories

3. Docusate
Stool softner that is often prescribed to prevent straining in hospitalized patients
Dietary supplements that add bulk & hold water to intestinal contents
Bulk-forming Laxatives
List 3 Bulk-forming Laxatives
1. Methyl-cellulose

2. Lactulose

3. Poly-carbo-phil

**My Large Poop
2 anti-diarrheal drugs that act on intestinal opioid receptors to decrease GI motility

Antidiarrheal that is 40-50 times more effective than morphine
-increases __1__ time and __2__ tone
-acts quickly on oral administration with peak levels at __3__
-effective against __4__, but should be discontinued if clinical improvement does not occur within 48 hours
1. intestinal transit
2. anal sphincter
3. 3-5 hours
4. Traveler's Diarrhea
2 Anti-diarrheal drugs that act by absorbing compounds and presumably binding potential intestinal toxins

List 5 of the most widely used Anti-diarrheal drugs
1. Loper-amide
2. Di-phenoxyl-ate
3. Di-fenoxin
4. Bismuth subsalicylate
5. Kaolin/Pectin
Vomiting is a complex process coordinated by a __1__ vomiting center that activates __2__ pathways in the __3__(3) nerves of the __4__ muscles
1. Medullary (medulla)
2. efferent
3. Vagus, Phrenic, and Spinal innervation
4. Abdominal
4 classes of Antiemetic drugs (anti-vomiting)
1. Histamine H1 antagonists
2. Dopamine D2 & Serotonin 5-HT3 antagonists
3. Pheno-thiazines & Benzo-diazepines
4. Marijuana derivatives
How do the Histamine H1 Antagonists provide anti-emetic activity?
Produce sedation & anti-muscarinic activity which prevent Motion Sickness
List the 4 Histamine H1 Antagonists used as Anti-emetic drugs
1. Di-men-hydrinate

2. Di-phen-hydramine

3. Cyclizine

4. Me-clizine
List the Dopamine D2 antagonists used as Anti-emetic drugs
1. Meto-clopramide

2. Tri-metho-benzamide

***"3 Meth dealers in a Benz-amide" take exit D2 to METOCLOPRAMIDE street
List the 3 HT3 antagonists that are currently used for nausea and vomiting during Cancer Chemotherapy


List the 2 Phenothiazines used as Anti-emetics


*the "Color Pro's" do not like to puke
List the 2 Benzodiazepines used as Anti-emetics

Marijuana derivative used as a prophylactic antiemetic in patients receiving cancer chemotherapy

**"Drawn Abs" on a Cancer patient will make them LAUGH (marijuana) instead of puke
What are the side effects of Dron-abinol?
Increased sympathomimetic activity in the form of marijuana-like highs
-mood changes
-paranoid rxns
-thinking abnormalities
2 Marijuana derivative used as Anti-emetics
1. Tetra-hydro-cannabinol (THC)

2. Dron-abinol