GI deck 3 Flashcards
Antiemetics may be used to provide
Symptom relief for nausea and vomiting
Prevention of fluid and electrolyte disturbances
Drug class of antiemetics
Antihistamines Phenothiazines Sedative hypnotics Anticholinergics Cannabinoids 5-HT3 receptor antagonists Substance P/neurokinin 1 (NK1) receptor antagonist
Antihistamines MOA
have strong anticholinergic effects as well as histamine1-blocking effects
phenothiazines MOA
block dopamine receptors in the chemoreceptor trigger zone
Cannabinoids MOA
work in the central nervous system (CNS) to prevent nausea and vomiting associated with cancer chemotherapy
5-HT3 MOA
receptor antagonists: block serotonin on vagal nerve terminals and in the chemoreceptor trigger zone
Anticholinergic example
scopolamine
antihistamine precautions
have anticholinergic properties
Phenothiazines
Produce and are contraindicated in
Produce extrapyramidal symptoms (EPS)
Contraindicated in Parkinson’s disease
Dronabinol use with caution in
in patients with seizure disorders
5-HT3 receptor antagonists: may mask
progressive ileus
Antihistamine ADR
Drowsiness
Anticholinergic effects of dry mouth, blurred vision, and urinary retention
Phenothiazines ADR
Drowsiness
EPS, such as dystonia, akathisia, and tardive dyskinesia
Most commonly used antiemetics
antihistamines and phenothiazines
Promethazine: fatal ____
respiratory depression in children younger than 2 years of age
Scopolamine ADR
Dry mouth
Withdrawal symptoms
Cannabinoid dronabinol ADR
dronabinol
Euphoria, depression, dizziness, paranoid thoughts, somnolence, and abnormal thoughts
Cardiac effects: palpitations, tachycardia, and hypotension
Seizure and seizure-like activity have been reported
Scopolamine is commonly delivered in the form of a
patch - used behind the ear for motion sickness. 24 hours before nausea inducing events. Sometimes pre surgery as well.
5-HT3 receptor antagonists
ADR
Constipation, headache, fatigue, dizziness, and diarrhea
Rare cases of tachycardia, bradycardia, hypotension, and heart rate-corrected QT interval prolongation
Dronabinol is only used for
chemotherapy-associated nausea and vomiting, and for appetite stimulation.
5-HT3 Example and what you should be aware of
Zofran
prolonged QT interval
Antiemetics addive ___ and ___
Additive CNS depression when combined with CNS depressants
Additive anticholinergic effects
Phenothiazines and lithium: may
Phenothiazines and lithium: may increase EPS
Phenothiazines and lithium: may mask lithium toxicity
Motion sickness drug used
Antihistamines
Dimenhydrinate and meclizine
Vomiting caused by gastroparesis drug uese
Prokinetic drugs
Aprepitant used in conjunction
with other antiemetic to prevent N&V associated with chemo
Antiemtics monitoring short term
use requires minimal monitoring
Antiemetics monitoring long term
use of promethazine requires complete blood count to monitor for bone marrow depression and blood dyscrasias (week 4 and week 10 of therapy).
Anitemetics should be taken
1 to 2 hours before departure to treat motion sickness
Dronabinol (Marinol): may cause
euphoria and behavior changes
Antiemetics lifestyle changes
Hydration
Electrolyte replacement solutions
H2RAs: reversible competitive
blockers of histamine at histamine2 receptors
Highly selective
Reduce gastric acid secretion by 35% to 50%
H2RA is a great choice
for addressing acid related problems. It works by blocking histamine which controls the potency of gastric acid secretion.
good for chronic acid problems. They are not acid neutralizing
Commonly H2RA
Ranitdine
Famotidine
Ranitidine is
5 to 12 times more potent than cimetidine
Famotidine is
30 to 60 times more potent than cimetidine
H2RA precautions and contraindications
Cautious use in renal impairment
Hepatocellular injury may occur with
nizatidine
Occasional reversible hepatitis or hepatocellular disorders have occurred with
rantidine
H2RA pregnancy category
B
Ranitidine and famotidine use is approved in
children
H2RA ADR
Antiandrogenic reactions
Gynecomastia and impotence
Cimetadine the worst offender
CNS adverse reactions
Agranulocytosis, granulocytopenia, thrombocytopenia, and aplastic anemia
H2RA monitoring
liver function with high-dose or long-term use
H2RA clinical use and dosing and no empiric treatment of
Gastroesophageal reflux disease (GERD)
Twice daily dosing
No empiric treatment of infants with GERD with H2RAs
are H2RA used in peptic ulcer disease
no
h2ra decreased dosing for
renal dysfunction
h2ra patient education
Take with meals.
Separate antacids by 30 minutes to 1 hour.
H2RA may cause
H2RAs may cause drowsiness or dizziness.
Cimetadine may cause gynecomastia and impotence in men
Smoking decreases absorption of
H2RA
ETOH can increase
gastric irritation
