Drugs Affecting the
Gastrointestinal System and
Nutrition
Jan Bazner-Chandler MSN, CNS, RN,
CPNP
Acid-related Pathophysiology
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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.
Antacids
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Are basic compounds used to neutralize
stomach acid.
OTC Products
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Antacids were the most common products
used for acid-indigestion until the 1970’s
when histamine-2 (H2 antagonists) were
developed.
Action
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Primary drug effect of antacids is the
reduction of symptoms associated with acidrelated disorders: pain and reflux (heartburn)
Raises gastric pH from 1.3 to 1.6.
Indications
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Acute relief of symptoms associated with:
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peptic ulcer disease (PUD)
Gastritis
gastric hyperacidity
Heartburn or gastro esophageal reflux (GEF)
GERD
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Most common disorder of esophagus
Characterized by regurgitation of gastric
contents into esophagus and exposure of
esophageal mucous to gastric acid and
pepsin.
Main symptom is heart burn - occurs after
eating
Cause is thought to be incompetent lower
esophageal sphincter
GERD
Peptic Ulcer Disease
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Ulcer formation in the esophagus, stomach or
duodenum
Mucous exposed to gastric acid and pepsin
Imbalance between cell-destructive and cellprotective effects
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Gastric acid and pepsin
H. pylori – infectious process
Peptic Ulcer Disease
Adverse Effects
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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).
Keep away from small children
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Alkalosis
Contraindications
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Allergy to the drug
Severe renal failure
Electrolyte disturbances
Gastro intestinal obstruction
Interaction
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May effect absorption of other drugs.
Chemically inactivates certain drugs
Increased stomach pH decreasing absorption
of acidic drugs
OTC Preparations
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Magnesium-containing antacids
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Aluminum-containing antacids
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Gaviscon Liquid, Milk of Magnesium
Amphogel, Maalox
Sodium-containing antacids
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Alka-seltzer, Tums
Gelusil / Mylanta
Administration
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Chewable forms needs to be thoroughly
chewed.
Liquid forms need to be shaken well before
taking.
Take with 8 ounces of water to enhance
absorption.
Do not take within 1 to 2 hours of taking other
medications – may effect absorption
H 2 Antagonists
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H2 receptor blockers
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cimetadine (Tagamet),
ranitidine (Zantac)
famotidine (Pepcid)
nizatidine (Axid)
H2 antagonist HAs
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Action:
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blocks the H2 receptor of acid-producing parietal
cells
Reduce hydrogen ion secretions to increase pH of
stomach
Therapeutic Uses
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GERD or gastro-esophageal reflux
PUD or peptic ulcer disease
Zollinger-Ellison Syndrome (excessive gastric
acidity)
Adverse Effects
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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
Proton Pump Inhibitors
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Newest drugs used in the treatment of acidrelated disorders.
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lansopraxole (Prevacid)
omeprazole (Prilosec)
rabeprzole (Acephex)
pantoprazole (Protonix)
exomepraxole (Nexium)
PPIs
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Action: Binds directly to the hydrogenpotassium - ATPase pump mechanism,
inhibiting the action of the enzyme which
results in a total blockage of hydrogen ion
secretion from the parietal cells.
Adverse Effects
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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.
Miscellaneous Acid-Controlling Drugs
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sucralfate (Carafate)
Uses: long-term therapy for PUD
Action: acts locally binding directly to the
surface of the ulcer.
Note: not used as often due to short-term
action and multiple daily dosing.
Cytotec
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Generic: misoprostol
Action: acts on prostaglandin E analogue
Indication: reduces the incidence of gastric
ulcers in patients taking NSAIDs.
Mylicon
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Generic: simethicone
Action: alters the elasticity of mucus-coated
gas bubbles, causing them to break down
into smaller ones
Mylicon
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Used to reduce the discomfort of gastric or
intestinal gas (flatulence)
Used post-operatively and in post-partum
patients to relieve gas pain.
Often used in combination with activated
charcoal in oral poisoning (overdose).
Probiotics
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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.
Probiotics
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Probiotics are available in foods and dietary
supplements. Examples of foods containing
probiotics are yogurt, fermented and
unfermented milk, miso, and some juices and
soy beverages. In probiotic foods and
supplements, the bacteria may have been
present originally or added during
preparation.
Probiotics
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Most probiotics are bacteria similar to those
naturally found in people's guts, especially in
those of breastfed infants (who have natural
protection against many diseases). Most
often, the bacteria come from two groups,
Lactobacillus or Bifidobacterium. A few
common probiotics, such as Saccharomyces
boulardii, are yeasts, which are different from
bacteria.
Uses
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Chronic Diarrhea
Irritable Bowel Syndrome
Digestive disorders
Clients on oral or IV antibiotic therapy
Status post abdominal surgery
Antidiarrheals and Laxatives
Chapter 42
Antidiarrheal Drugs
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Used to treat diarrhea.
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Adsorbents
Antimotility (anticholenergic and opiates)
Intestinal flora modifiers or bacterial replacement
drugs
Adsorbents
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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.
Pepto-Bismul and Kaoectate
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Generic: bismuth subsalicylate
Same chemical structure as salicylate
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use with caution in children. May cause Reyes
Syndrome
Use with caution in clients who are on anticoagulation therapy.
Pepto-bismol
FDA Warning
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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.
Anticholinergics
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Used either alone or in combination with
other antidiarrheal drugs.
Acts by slowing GI tract motility
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Atropine
hyoscyamine
hyoscine
Opiates
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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
Imodium A D
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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)
Laxatives
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Laxative act by:
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Affecting the consistency of the stool
Increasing fecal movement through the colon
Facilitating movement through the colon
Constipation
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Definition: abnormally infrequent and difficult
passage of feces.
Constipation is a symptom not a disease.
Bulk-forming Laxatives
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Composed of water-retaining natural and
synthetic cellulose derivates.
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Psylium is an example of natural bulk-forming
laxative.
Methylcellulose is an example of a synthetic
cellulose derivative.
Bulk-forming Laxative
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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.
Citrucel (methylcellulose)
Nursing Alert
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Have client take with 8 ounces of water.
If powdered form needs to be mixed with 8
ounces of water.
Fluid must be taken immediately to avoid
swelling of the product in the throat or
esophagus or fecal impaction.
Best for clients with chronic constipation.
Emollient laxative
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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.
Emollients
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Uses:
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post partum
postoperative patients
Clients on long-term pain control
Outcomes: soft stool with easier defecation
Mineral Oil
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Action: eases the passage of stool by
lubricating the intestines and preventing
water from escaping the stool.
Contraindications
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Abdominal pain
Nausea and vomiting
Intestinal obstruction
Hyperosmotic Laxatives
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Glycerine
Action: promotes bowel movement by
increasing the osmotic pressure in the
intestine.
Note: given in the form of a suppository
Stimulant Laxatives
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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.
Stimulant Laxatives
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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.
Irritable Bowel Syndrome IBS
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A condition of chronic intestinal discomfort,
including cramps, diarrhea / or constipation.
Two drugs to manage symptoms:
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Lotronex (alostron) – approved for women only
Zelnorm (tegaserod) – approved for men and
women
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Action: works on serotonin receptors in the intestinal
tissue.
Antiemetic and Antinausea
Drugs
Chapter 52
Chemoreceptor Trigger Zone (CTZ)
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The area of the brain that is involved in the
sensation of nausea and the action of
vomiting.
Vomiting Center (VT)
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The area of the brain that is involved in
stimulating the physiologic events that lead to
nausea and vomiting.
Antiemetic Drugs
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Drugs used to relieve nausea and vomiting.
All emetic drugs work at some site in the
vomiting pathways.
Syrup of Ipecac
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AAP recommendations in 2003 issued an
alert to stop the use of this drug to induce
vomiting after drug overdose.
Anticholinergic Drugs
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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.
Antihistamines
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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
Neuroleptics
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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.
Compazine: Nursing Alert
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Adverse reaction: extrapyramidal reaction--a
muscle spasm of the tongue. Other typical
adverse extrapyramidal reactions include
tremors, drooling, and muscle spasms that
usually involve muscles in the shoulders,
neck, or eyes.
Antidote: Benadryl
Prokinetics
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Metoclopramide
Trade name: Reglan
Action: promote the movement of substances
through the GI tract and increases motility.
Often given in patients getting tube feeding to
promote gastric emptying time.
Serotonin Blockers
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Called 5-HT3 receptor blockers because they
block the 5-HT3 receptors in the GI tract,
CTZ and vomiting centers VC.
Four drugs in this category
ondansetron
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Trade name: Zofran is the prototype drug.
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Approved in 1992.
Major break through in treating chemotherapy induced
nausea and vomiting and postoperative nausea and
vomiting.
Approved for use in pregnancy.
Side effects from all antiemetics
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May cause dizziness
Caution with use while driving.
CNS depression
Hypotension
Herbal Therapies
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Ginger Root
May increase absorption of all oral
mediations, may increase bleeding in clients
taking Coumadin and Plavix.