Gastrointestinal Drugs
Objectives
Discuss
Discuss the use of
medications for
emesis, motion
sickness, diarrhea,
irritable bowel
syndrome,
inflammatory bowel
syndrome, & obesity
Discuss
Discuss the nursing
implications for
patients receiving
these medications
Identify
Identify adverse
effects and MOA for
key drugs/drug
classes
Drugs/Topics Covered…
Antiemetic
Agents
Drugs for
Motion
Sickness
Antidiarrheal
agents
Drugs for
Irritable Bowel
Syndrome
Drugs for
Inflammatory
Bowel Disease
Prokinetic
Agents
Pancreatic
Enzymes
Drugs for
Gallstones
Anorectal
Preparations
Drugs for
Treating
Obesity
Antiemetics
Why are they administered?
Common Causes:
• GI disorders
• Infections
• Drug Therapy
• Pain
• Emotions
• Radiation
• Motion
• Post-op
• Pregnancy……
Vomiting Center located in the
medulla
Antiemetics
Normal Physiology
Signals from sensory
organs
Direct stimulation
Signals from the cerebral
cortex
Signals from the vestibular
apparatus
Indirect stimulation
Activation of the
chemoreceptor trigger
zone (located near the
vomiting center)
•Stimulated by signals
from stomach and small
intestine
•Direct action of
emetogenic compounds
Receptors involved in the vomiting response
• Serotonin
• Dopamine
• Acetylcholine
• Histamine
• Neurokinin
Most effective agents for N/V related to
chemo/radiation/anesthesia
Antiemetics
Serotonin
receptor (5HT3)
Antagonists
• Prototype: Ondansetron (Zofran)
Medicate 30 to 60 minutes prior to chemotherapy
More effective when used with dexamethasone
Side effects: diarrhea, HA, dizziness
Monitor for prolonged QT on EKG
Antiemetics
Serotonin Receptor (5-HT3) Antagonists
Other 5-HT3 Antagonists
Granisetron (Kytril)  IV, PO, Transdermal
• Similar to Ondanestron
Palonosetron (Aloxi)  IV only
• Longer acting (longer half life)
• Effective for Acute & Delayed N/V
Dolasetron (Anzemet) – older drug
• Dysrhythmias!!!
Substance P/Neurokinin1 Antagonists
MOA  blocks Neurokinin 1
receptors
Therapeutic use 
prevention of CINV When
combined with other
antiemetics
Prototype  Aprepitant
(Emend)
• A 5HT3 antagonist and a
glucocorticoid
Think suffix – pitant
Adverse effects  fatigue,
hiccups, dizziness & diarrhea
Drug Interactions  inhibits
several liver metabolizing
enzymes (Ex: decrease levels
of warfarin & oral
contraceptives; increase
glucocorticoid levels)
Antiemetics
Dopamine Antagonists
Phenothiazines
 Prochlorperazine (Compazine) - Prototype
 Promethazine (Phenergan)
Due to blockade of dopamine receptors, may cause
extrapyramidal side effects (acute dystonia, akathisia) “Act
like Dopey”
***don’t use promethazine in children <2 years old***
***caution use in children > 2 ***
Lorazepam (Ativan), a benzodiazepine, is used in combination
regimens for CINV as an adjunct therapy.
**Also, helps control EPS secondary to phenothiazines**
Extrapyramidal Side Effects
Image obtained from www.pinterest.com
Antiemetics:
Cannabinoid
Dronabinol (Marinol)
 Pharmacotherapeutics:
• N/V associated with cancer chemotherapy
(CINV)
• Appetite stimulant in patients with AIDS
 Unknown Mechanism of Action (MOA)
• Thought to activate cannabinoid receptors
 Adverse effects: dissociation, dysphoria
 Use caution in clients with cardiac disease
 Slow onset of action
 Do not take with alcohol, CNS depressants
 Abuse potential – DEA Schedule III
-Increase tone and motility of GI tract
Prototype agent: Metoclopramide (Reglan)
Prokinetic
Agents
Therapeutic Uses
• Nausea & Vomiting related to gastroparesis, GERD ???,
post-operatively, chemotherapy
Mechanism of Action
• Sensitizes tissues to the effect of acetylcholine
• Increases peristalsis & gastric emptying
• Dopamine receptor antagonist with antiemetic effects
on the CTZ
Adverse effects
Prokinetic
Agents:
• CNS depression
• EPS
• Tardive Dyskinesia, Acute Dystonia, Parkinsonism,
Akathisia
• Diarrhea  Why?
Metoclopramide
(Reglan)
Nursing Administration
• Traditionally, give prior to symptoms of N/V
• 30 minutes prior to a meal
Do not use in bowel obstruction, perforation
Antispasmodics
Cholinergic nerve fibers are throughout
the gastrointestinal tract and when
stimulated cause increased motility and
secretion of acids and enzymes.
Antispasmodic agents are
anticholinergic agents
• So what do we expect these drugs to do??
• Which side effects would you expect?
A Quick Review….
PNS effects when stimulated:
SLUG BAM
Think of getting
(cholinergic effects)
• Salivation, secretions, sweat
• Lacrimation
• Urination
• GI upset (diarrhea)
• Bradycardia, BM, Bronchoconstriction,
• Abdominal cramps, Anorexia
• Miosis
wetter like a
Slug
hortipm.tamu.edu
ANTIcholinergic Side Effects
If cholinergic agents make you “wet”, then
ANTIcholinergic agents make you ”dry”
• Can’t pee
• Can’t see
• Can’t spit
• Can’t poop
urinary retention
blurred vision
dry mouth
constipation
Drugs for Motion Sickness


Anticholinergic/Muscarinic antagonist
 Scopolamine
• Most effective for motion sickness
• Adverse effects: dry mouth, blurred vision, &
drowsiness
• Po, Subcutaneous, or Transdermal
Anticholinergic/Antihistamines
 Dimenhydrinate (Dramamine) &
Meclizine (Antivert)
• Dry mouth, blurred vision, drowsiness, and
sedation
Antidiarrheal Agents
Let’s Talk about Diarrhea…
• Diarrhea
• Symptom of GI disease
• Causes: Infection, maldigestion, inflammation,
and functional disorders
• Complications:
• Dehydration and electrolyte imbalances
• What else??
• Treatment
• Diagnose & treat the cause
• Replace lost fluids
• Relive cramping
• Decrease amount of stool
What do these meds do to GI
motility?
Antidiarrheal
Agents
Prototype agent:
Diphenoxylate HCl
with atropine sulfate
Controlled
substance
Atropine added
to discourage
misuse
Contraindications:
Lomotil:
Diphenoxylate
HCl with
atropine
sulfate
• diarrhea of infectious nature
• obstructed jaundice
• children under age 2
Adverse effects: related to opioids & anticholinergics
(mostly in high doses)
Drug interaction: MAO inhibitors
Opioids: Controlled substance (Schedule V)
Atropine added to discourage misuse
More Antidiarrheal Agents
Loperamide (Imodium)
• Used in treatment of acute or chronic diarrhea
(gastroenteritis)
• Little to no abuse potential
• Does not contain atropine
• Less adverse effects
Difenoxin with atropine (Motofen)
• Higher abuse potential (Schedule IV)
Bismuth Subsalicylate (Pepto Bismol)
• Age related concern (ASA and Children)
• Adverse effects  like what??
Other
Antidiarrheals
Kaolin and Pectin (Kaopectate)
• Adsorbent
• Absorbent – promotes intestinal absorption of fluid and
electrolytes
Sometimes, bulk-forming laxatives and
antibiotics
All antidiarrheals must be used with caution in
patients with IBD  WHY??
Inflammatory Bowel Disease (IBD)
• Ulcerative Colitis
Crohn’s Disease
IBD vs IBS
Irritable Bowel Syndrome (IBS)
Unknown cause
Hyper-sensitive/hyper-responsive bowel
Alosetron (Lotronex) (PO)

Irritable
Bowel
Syndrome
For use in women only with severe
disease
• What are the expected therapeutic
effects??
MOA: blocks 5-HT3 receptors in lower GI
tract
 Fatal GI effects

• Constipation  obstruction  perforation
• Ischemic colitis

Need to follow strict criteria and consent
to a risk management program
• When should this drug not be taken??
Irritable
Bowel
Syndrome
• Lubiprostone (Amitiza)
• Linaclotide (Linzess)
• Other possible medications: tricyclic
antidepressants, antispasmodics, antidiarrheals,
bulk forming meds, and antibiotics
Inflammatory
Bowel Disease
Drug Therapies
Pharmacological
Treatments:
5-Aminosalicylates
Glucocorticoids
Immunomodulators
Antibiotics
Immunosuppressants
• Metronidazole (Flagyl)
• Ciprofloxacin (Cipro)
Inflammatory
Bowel Disease
Drug Therapies
5-Aminosalicylates
Sulfasalazine (Azulfadine)
• Anti-inflammatory effect
• Contraindication: be aware of sulfa allergies
• Nursing administration: give with food & monitor CBC
Mesalamine (Asacol, Cantasa, Pentasa,
Rowasa)
• Better tolerated than sulfasalazine
Others: Olsalazine (Dipentum) &
Balsalazide (Colazal, Giazo)
Inflammatory
Bowel Disease
Drug Therapies
Glucocsorticoid
• Intravenous
• Hydrocortisone, Methylprednisolone, or
Dexamethasone
• Oral
• Prednisone, Methylprednisolone, or
Dexamethasone
• New  Budesonide
Administration and Patient Teaching
Nursing Assessments?
Inflammatory
Bowel Disease
Drug Therapies
Immunosuppresants
• Azathioprine (Imuran) &
Mercaptopurine (Purixan)
• For refractory disease, onset of
action may take up to 6 months
• Adverse effects: pancreatitis &
bone marrow suppression
• Monitor lab values  which
ones??
• Cyclosporine
• Methotrexate
Inflammatory
Bowel Disease
Drug Therapies
Immunomodulators
Infliximab (Remicade) (IV)
Monoclonal antibody (TNF inhibitor)
For mod to severe IBD
IV infusion
• Risk for hypersensitivity/infusion reaction
Ustekinumab (Stelara) (IV, SubQ)
Monoclonal antibody that blocks specific interleukins
Used for exocrine pancreatic insufficiency (EPI)
People who can’t digest food normally because their
pancreas does not make enough enzymes
Pancreatic
Enzymes
-Normally  Enzymes are secreted into the duodenum,
digest fats, carbohydrates & proteins.
-Deficiency of pancreatic enzymes compromise
digestion especially of fats.
-If pancreatic enzyme secretion is reduced, replacement
therapy is needed
-All drugs except Viokase tablets are delayed release
capsule so they dissolve in the duodenum
Deficiencies
in pancreatic
enzymes
occur in:
Cystic Fibrosis
Duct Obstruction
Pancreatectomy
Chronic Pancreatitis (swelling
of the pancreas that lasts a
long time). CP may cause
irreversible damage to the
pancreas, including the cells
that make digestive enzymes
-*Fatty stools are
characteristic, foul smelling*

Pancrelipase
(Creon)

Helps break down food into fats, proteins, and
carbohydrates that your body can use
Enteric coated, contains
 lipase,
 protease,
 & amylase
May be from bovine or porcine source
Adverse effects: abdominal discomfort,
flatulence, headache, & cough.
Pancrelipase
Do not crush or chew capsule; can
cause irritation in the oral mucosa.
How do we know if a patient is
experiencing a therapeutic effect?
Review of pathophysiology (see note section)
Chenodiol (Chenodeoxycholic Acid)
GallstoneSolubilizing
Agents
Naturally occurring bile acid
Reduces the hepatic production of cholesterol
Used to promote the dissolution of cholesterol
gallstones in selected patients
Pregnancy Category X
GallstoneSolubilizing Agents
Urosdiol (Actigall):
• Reduces cholesterol content of
bile
• Emulsifies bile salts in small (less
than 20 mm) cholelithiasis or
cholesterol stones.
**Like Chenodiol, does not reduce
radiopaque stones (stones with
significant calcium content)
This Photo by Unknown Author is licensed under CC BY-SA
Anorectal
Preparations


Used to relieve pain of hemorrhoids & other
anal disorders
Combination of Topical Agents
 Local anesthetics (benzocaine)
 Glucocorticoids (hydrocortisone)
 Emollients (mineral oil)
 Astringents (witch hazel)
 Nitroglycerin ointment (for anal fissures)
Body Mass index kg/m2 & Waist circumference
Overview of
Obesity
Treatment
Risk factors
Rule out other causes of obesity
Bariatric Surgery
Drug therapy used as an adjunct to diet, exercise, &
behavior modification for management of obesity
• BMI 30 kg/m2 or 27 kg/m2 with cardiovascular risk factors
Lipase Inhibitors
• Orlistat (Alli, Xenical)
Types of
Medications
for Treating
Obesity
Appetite Suppressants
• Lorcascerin (Belviq) – 5-HT2c receptor agonist
• Liraglutide (Saxenda) - GLP-1 agonist
• Diethylpropion & Phentermine - both are
Sympathomimetic Amines
Combination Products
• Phentermine/Topiramate
• Naltrexone/Bupropion
Prototype agent: Orlistat (Xenical, Alli)
Pharmacodynamics:
Lipase
Inhibitors
• lipase inhibitor, reduces absorption of dietary fats
Diet: reduced fat intake, (less than 30% fat calories)
Contraindications: chronic malabsorption syndrome or
cholestasis
Common adverse effects: GI effects – oily fecal incontinence,
etc.; decreased absorption of fat soluble vitamins
Watch for s/s of liver damage
Prototype agent: Orlistat
(Xenical, Alli)
Lipase
Inhibitors
To prevent drug interactions:
• Take fat soluble vitamins 2 hours before
or 2 hours after Orlistat
• Watch warfarin dosing (due to risk for K
deficiency)
• Space dosing of Orlistat and
levothyroxine 4 hours apart
Appetite Suppressan:
Lorcaserin (Belviq)
Acts on serotonin receptors in brain
• 5-HT2c Agonist
Decreases appetite
Increases feeling full with smaller meals
Most common adverse effects
• Anticholinergic effects, headache, back pain, hypoglycemia (in DM)
Do not take with SSRIs or MOA inhibitors (bc it’s a serotonin agonist)
Appetite Suppressant:
GLP-1 Agonist
Liraglutide (Saxenda) (SubQ)
• MOA:
• Decreases gastric emptying  feel full
• decreased oral intake
• Common adverse effects: Increased HR, GI
symptoms, Headache, Hypoglycemia (in DM)
• Watch other meds (as can lower blood sugars)
Appetite Suppressant:
Sympathomimetic Amines
Non amphetamines & Amphetamines
• increase availability of norepinephrine
• suppress appetite
Approved for short term use only
Adverse effects of CNS & CV stimulation
High potential for abuse with amphetamines – Not approved by FDA
Non-amphetamines- are approved by FDA
Appetite Suppressant:
Sympathomimetic
Amines
• Increase neurotransmitters in brain
that affect appetite and make you feel
full
• FDA Approval ONLY for short term use
• Up to 12 weeks
• Examples
• Phentermine
• Diethylpropion
• Which adverse effects would you
expect?
Combo med: for greater
results
Phenterminetopiramate
(Qsymia)
• Phentermine = appetite suppressant
• Topiramate = increases feeling full
Adverse Effects
• Anticholinergic effects plus
insomnia, taste alteration, impaired
memory, & difficulty concentrating
Combo med
Naltrexone/bupropion
(Contrave)
MOA for weight loss unknown (affects hypothalamus &
dopamine reward system?)
Adverse effects: n/v, headache, dizziness, increased BP,
insomnia
Safety Alert  Risk for suicide and neuropsychiatric
reactions (when combined with bupropion or other meds
withdrawn quickly)
New (Evidenced Based):
Current
Events:
Updates &
New Drugs
• Granisetron transdermal patch
(Sancuso)
• New indication Pregnancy induced
nausea & vomiting
• Continued use in CINV
• Olanzapine (oral wafer)
• Success in CINV in stem cell transplant
recipients
• Several other studies have supported
use in preventing and treating CINV
Updates (EBR/EBP Guidelines):
Current
Events:
Updates &
New Drugs
Double, triple, or quadruple antiemetic therapy
recommendations in Oncology (vary due to
emetogenic potential of chemo/radiation)
• Neurokinin 1 receptor antagonists
• 5HT3 receptor antagonists
• Dexamethasone
• Olanzapine (added if highly emetogenic)
Cannabinoids  insufficient evidence to
support use in chemo/radiation induced nausea
or vomiting (per ASCO guidelines)