Drugs For Treating Gastrointestinal Disorders Flashcards
1
Q
GI Anatomy/Physiology
A
The GI tract is a long tube, which digests and absorbs food, liquids, and chemicals.
2
Q
GI Anatomy/Physiology: Stomach
A
- Lined with parietal cells that increase gastric acid formation
- Lower Esophageal Sphincter (LES)
~ Prevents stomach contents from
entering the esophagus - Pyloric Sphincter
~ Prevents intestinal enzymes and bile
from entering stomach.
~ Prevents stomach acid from entering
the small intestine.
3
Q
Gastric Acid
A
- Hydrochloric Acid (HCI)
~ Gastric acid always produced
> Activates pepsin for protein
digestion
> Kills bacteria
~ Rate of production increases:
> At night due to parasympathetic
NS stimulation
> With slight smell of food or food in
the stomach - The stomach is lined with a mucous membrane that helps to protect from acid irritation
4
Q
Mechanism for Gastric Acid Increase
A
- Presence of food stimulates release of:
(see it, smell it, eat it)
~ Gastrin
~ Acetylcholine
~ Histamine - Parietal cells have receptors for all three chemicals.
~ Binding to receptors activates the
proton pump within the parietal cells.
5
Q
Proton Pump
A
- Actively transports hydrogen atoms into the stomach
~ Hydrogen atoms combine with
chloride ions and from hydrochloric
acid
6
Q
Heartburn/Gastroesphegeal Reflux Disease (GERD)
A
- Gastric acid enters the esophagus causing a burning sensation
~ Can break down the esophagus as it
lacks the protective membrane of the
stomach
7
Q
Heartburn/Gastroesphegeal Reflux Disease (GERD): Cause
A
- LES is relaxed
- Activity increasing intra-abdominal pressure
~ Coughing
~ Sneezing
~ Laughing
~ Lifting/pushing objects
8
Q
Heartburn/Gastroesphegeal Reflux Disease (GERD): Worsening Factors
A
- Foods/Drugs that Increase Stomach Acidity
~ Chocolate
~ Carbonated Beverages
~ Orange/Tomato Juice
~ Peppermint/Spearmint
~ Garlic
~ Onions
~ Caffeine
~ Aspirin (acetylsalicylic acid) - Foods/Drugs that Slow Digestion
~ Large Meals
~ Fatty Meals
~ Blood Pressure Medications
~ Opioid Agonists - Drugs that Decrease LES Function
~ Antidepressants
~ Anticholinergics
~ Beta Agonists
~ Sedatives
9
Q
Peptic Ulcer Disease
A
- Chronic erosion of the stomach lining and wall
- Cause
~ Gastric acid causes damage after
protective mechanism in stomach fails - Can cause a whole all the way through and cause internal bleeding
10
Q
Stomach Protection vs. Gastric Acid
A
- Mucous lining
- Bicarbonate buffer secretion
- PGE2 (Fever)
~ Inhibits Proton Pump = less acid - PGI2 (blood thinner)
~ Increases mucous lining production
~ Increases bicarbonate buffer secretion
> Good, but can be the reason why
taking NSAIDs are bad long term - Protective mechanisms compromised by:
~ NSAID/Aspirin Use
> PG Production Inhibited
• PGE2
• PGI2
> Acidic Compounds
~ H. pylori Infection
> H. pylori is a Gram-negative
bacterium. (treat w/ antibiotics)
• Contaminated food or water.
11
Q
Effects of H. pylori in the Stomach
A
- 30-65% of all people have this bactenum in the stomach, but it does not always result in ulceration.
~ Produces enzyme that breaks down
the mucous lining of the stomach
~ Immune response can also damage
tissues
12
Q
Proton Pump Inhibitors
A
- Drug Action
~ Inhibits Proton Pump
> Irreversibly inhibits enzyme that is
part of the proton pump so that
acetylcholine, gastrin, and
histamine binding has less effect
on stomach acid formation.
• Good for GERD and peptic ulcer
• One dose per day is effective.
> Some inactivated by gastric acid,
but must pass to the small
intestine (shouldn’t be chewed or
crushed because it be broken
down further)
13
Q
Proton Pump Inhibitors Adverse Effects
A
- Headache
- Dizziness
- Nausea
- Constipation
- Diarrhea
- Can increase the effects of drugs that are metabolized by the same enzyme
~ Warfarin (anticoagulant)
~ Phenytoin (anticonvulsant)
~ Benzodiazepine (anti anxiety)
14
Q
H2 Receptor Antagonist
A
- In the GI tract HT binds to H2 receptors
~ Activates the proton pump - H2 receptor antagonist block the binding of HT to the H2 receptors inhibiting the proton pump
~ Good for GERD and peptic ulcer - Not as effective as Proton Pump inhibitors because those target the whole system
15
Q
H2 Receptor Antagonists Adverse Effects
A
- Headache
- Diarrhea
16
Q
Antacids
A
- Introduction of a base to neutralize stomach acid
~ Much less effective/shorter duration
than proton pump inhibitors or H2
antagonists.
~ Faster acting than proton pump
inhibitors or H2 antagonists.
17
Q
Antacids Adverse Effects
A
- Aluminum Hydroxide
~ Decreases smooth muscle motility -
Constipation - Magnesium Hydroxide
~ Draw water from small intestine lining
- Diarrhea - Calcium Carbonate/Sodium Bicarbonate
~ React with gastric acid and for COz -
Belching/Abdominal Distention - Aluminum, magnesium, and calcium can
bind to some drugs (tetracycline). - Raising pH can decrease absorption of other drugs (NSAIDS)
18
Q
Lower GI Anatomy and Physiology
A
- Small Intestine:
Major site of digestion and absorption of carbs, lipid, protein. - Large Intestine:
Absorption of water & elimination of solid waste.
19
Q
Constipation
A
- Abnormal retention of feces
~ Causes
> Dehydration
> Decreased Bowel Motility
> Limited Fiber Intake
> Medications
> Disease
20
Q
Laxatives: Bulk Forming
A
- Composed of plant products with cell wall that cannot be digested.
~ Increases bulk
~ Absorbs fluid adding more bulk
~ Stimulates intestinal afferents
causing peristalsis and mucus
production. - Ex
~ Metamucil
~ Citrucel - Can bind with some drugs decreasing their absorption
~ Tetracycline
~ Warfarin (blood thinner)
21
Q
Laxatives: Osmotic
A
- Ingestion of a salt/sugar/fat solution.
- Component of solution not well absorbed.
~ Modifies osmotic balance causing
water to move into the intestine to
stimulate intestinal afferents causing
peristalsis and mucous production - Ex
~ Miralax
22
Q
Laxatives: Stimulant
A
- Stimulate smooth muscle in the intestine to increase motility/contractility
- Ex
~ Ex-Lax
~ Dulcolax
~ Castor oil - These will go into effect immediately so need to be mindful of when taking
23
Q
Stool Softeners
A
- More preventive for constipation
- Help fat and water to mix
~ Softens stool and facilitates
movement - Ex
~ Colace
~ Mineral oil
24
Q
Diarrhea
A
- Frequent and loose bowel movements
- Causes
~ Excessive Excretion - Infectious
organism produces excess secretion
of water and electrolytes.
~ Inflammation - Infectious organism or
condition inflames the wall of the
intestines causing exudate
production.
~ Osmotic Imbalance - Concentrated
substances can not be absorbed,
results in flow of fluid into the
substance and out of tissues.
25
Q
Anti-diarrheals: Opioids
A
- Bind to opioid receptors
~ Inhibit afferents lining the bowel
> Decreased Motility/Contractility
> Decreased Intestinal Secretion - Opioids used for diarrhea do not penetrate CNS well so abuse potential is small.
- Ex
~ Imodium
~ Lomotil
~ Motofen
26
Q
Anti-diarrheals: Bismuth Subsalicylate
A
- Converted to salicylic acid and bismuth oxycholride.
~ Salicylic acid (aspirin) decreases
inflammation
~ Bismuth oxychloride has antacid and
antibacterial effects - Same considerations when using aspirin:
~ Not for children with viral infection.
~ Not for anyone taking blood thinners.
~ Not for anyone with aspirin allergy. - Ex
~ Pepto Bismol
~ Kaopectate
27
Q
Irritable Bowel Syndrome
A
- Bowel symptoms and changes in habits without any identifiable, underlying cause.
~ Should not be confused with
inflammatory bowel disease.
~ Appears to be an idiopathic functional
disorder
28
Q
Irritable Bowel Syndrome S&S
A
- Pain
- Bloating
- Cramping
~ Symptoms usually resolve following
elimination. - Abnormal Bowel Habits
~ More than 3X per day (diarrhea)
~ Less than 3X per week (constipation)
~ Incomplete Bowel Movement - Abnormally hard or loose stool.
- Urgency
