5. ANTIEMETICS
DRUG NAME ondansetron metoclopramide aprepitant
CLASS 5-HT3 receptor antagonist
D2 dopamine receptor
antagonist
Neurokinin receptor antagonist
MECHANISM
OF ACTION
Decreases vagal nerve stimulation
(peripheral action); blocks chemoreceptor
trigger zone
Blocks dopamine D2 receptors
→ decreases dopamine levels;
crosses blood-brain-barrier
Blocks substance P from
acting at the neurokin-1
receptors
INDICATIONS
•Postoperative nausea / vomiting
•Chemotherapy / radiotherapy-induced nausea / vomiting
•Diabetic gastroparesis
•Postoperative vomiting
•Chemotherapy-induced
vomiting
ROA PO, IV, IM PO, NAS, IV, IM,SubQ PO, IV (fosaprepitant)
SIDE EFFECTS
•Headaches
•Gastrointestinal disturbances
•QT prolongation
•Serotonin syndrome
•Hyperprolactinemia,
•Gastrointestinal disturbances
•Restlessness, Fatigue,
Drowsiness, Depression
•Dry mouth, rash, pruritus, and
urticaria, or hives, arrhythmias
•EPS symptoms
•Headaches
•Dizziness, Fatigue, Hiccups
•Gastrointestinal disturbances
•Hair loss
•Skin rash
•Blood disorders
CONTRA-
INDICATIONS
AND
CAUTIONS
•Combination with other medications that
increase serotonin levels (e.g., SSRIs,
MAOIs)
•Prolonged use (>12 weeks)
•Severe hepatic disease
•Interacts with warfarin,
grapefruit juice
6. ANTIEMETICS
DRUG NAME
prochlorperazine,
promethazine
diphenhydramine dronabinol (Marinol)
CLASS Phenothiazine Antihistamine; H1 Cannabinoid
MECHANISM OF
ACTION
Blocks dopamine, cholinergic and
histamine receptors
Blocks histamine H1
receptors
Activates cannabinoid
receptors in the brain
INDICATIONS
•Chemotherapy- induced nausea /
vomiting
•Motion sickness
•Motion sickness
•Nausea / vomiting
•Allergic reactions
•Chemotherapy- induced
nausea / vomiting
ROA PO, PR, IV, IM PO, IV, IM PO
SIDE EFFECTS
•Antidopaminergic effects:
hyperprolactinemia, parkinsonism
•Anticholinergic effects
•Antihistamine effects: sedation
•Boxed warning
(promethazine): vesicant
•Antihistamine effects:
sedation, increased
appetite, weight gain
•Anticholinergic effects
•Anti-α-adrenergic effects:
orthostatic hypotension,
dizziness
•CNS effects: drowsiness,
dizziness, confusion,
delusions, anxiety,
euphoria
•Increased appetite
•Gastrointestinal
disturbances
CONTRA
INDICATIONS
AND CAUTIONS
•Boxed warning
(prochlorperazine): increased
mortality in elderly clients with
dementia-related psychosis
7. ANTIEMETICS
ASSESSMENT AND
MONITORING
•Symptoms: Onset, duration and frequency; emesis characteristics; fluid intake; urine output;
associated symptoms; e.g., abdominal pain, light-headedness, fever
•Vital signs; note signs of dehydration; abdominal assessment
•Laboratory and diagnostic test results: CBC, electrolytes, renal and hepatic function; ECG for
QT prolongation
•Monitor for side effects: Drowsiness, QT prolongation, anticholinergic, extrapyramidal,
serotonin syndrome
•Evaluate for desired outcomes: Reduced nausea and vomiting, balanced hydration and
electrolytes, adequate nutritional intake increased comfort
CLIENT
EDUCATION
•Comfort measures - Cleansing face and with cool washcloth; performing mouth care between
episodes of vomiting
•Drink clear liquids as tolerated, sipping small amounts every 15 to 20 minutes is better
tolerated; try eating foods with a lot of liquid in them (e.g., gelatin or popsicles); crackers or dry
toast can help settle their stomach
•Contact healthcare provider if worsening vomiting, decreased urinary output, extrapyramidal
side effects
•Ondansetron disintegrating tablet
Take with or without food, allow the
tablet to dissolve in their mouth without
chewing or swallowing whole
•Remind them to protect unused tablets
from moisture
•Promethazine
Ensure proper IV catheter placement into a large vein
•Instruct the client to immediately report pain /
burning if extravasation is suspected
•Stop the infusion for suspected extravasation
•Extravasation management measures
