Seth Pertuset, Pharmacy, 02/24/2025
Anti-emetics
D2
M1
AcH
H1
Ondansetron
5HT3
++++
QTc
effect
↑
Dose
4-8 mg IV/PO Q8H PRN
↑
5-10 mg IVq4-6h PRN (max 40 mg)
↑
25 mg IV or IM q4-8 hours PRN
↑
12.5-25 mg q12h PRN (oral or IM)
Prochlorperazine
++++
++
++
Chlorpromazine
++++
++
++++
Promethazine
++
+++
++++
Metoclopramide
+++
++
↑
IV= 10—20 mg as a single dose
Oral= 10 mg q4-6h PRN
Haldol
++++
+
↑
0.5-2 mg q6-8H PRN
Olanzapine
+
++
Minimal
continuous subQ 1-5 mg Q24h
5-10 mg/day (IV/IM)
Max 20 mg/day
1.
2.
3.
4.
5.
6.
+
+
+
Primary Uses
Gastroenteritis, opioidinduced, Post-op
(prevention), pregnancy (2nd
line)
Migraines, Pregnancyinduced nausea,
Gastroenteritis
Migraines,
Migraines, Pregnancyinduced nausea (2nd line),
Gastroenteritis
Migraines, pregnancy,
gastroparesis (1st line), postop nausea
Multi-factorial etiology,
gastroparesis (2nd line)
Refractory nausea, chemoinduced
5-HT3 Receptor Antagonists (Ondansetron)
a.
Side effects: QTc prolongation, serotonin syndrome, headache, diarrhea, and constipation
b. Renal/Hepatic Considerations: Child Pugh Class C= Max 8 mg in 24 hours
Phenothiazines (prochlorperazine, chlorpromazine, promethazine)
a. Broad mechanism of action by acting on D2, H1, 5HT3, and AcH receptors
i. Prochlorperazine= Very selective for D2 receptors
ii. Chlorpromazine= Typically only utilized once promethazine is failed
iii. Promethazine= IV is not utilized due to extravasation risk.
b. Side effects:
i. ***Extrapyramidal Side effects (dystonia, tardive dyskinesia, akathisia, and pseudo-parkinsonism),
QTc prolongation, and sedation
Metoclopramide
a. Dosing Considerations:
i. Reduced by 50% if CrCl is between 10-60 and moderate/severe liver impairment (max 5 mg QID)
1. Elderly population may consider 5 mg at initiation
b. Side Effects
i. Extrapyramidal side effects, history of seizure disorder, Parkinson’s disease
Haloperidol
a. Side effects/Contraindications= QTc prolongation, sedation, extrapyramidal side effects
Olanzapine
i. Minimal QTc prolongation
ii. Long half life (~50 hours), hepatic and elderly patients start low
iii. Lower risk for extrapyramidal effects, elevated sedation
Other
a. Antihistamines (meclizine, promethazine, diphenhydramine )= Limited use in nausea, may be beneficial for
Parkinson’s patients
i. Doxylamine= Anti-emetic of choice in pregnancy
b. Glucocorticoids
i. Last line due to taking 4-5 hours to take effect.
ii. Common agent= Dexamethasone 4-10 mg once before or after anesthesia
c. Lorazepam: 0.5-1mg Q6H PRN (drowsiness, weakness, fall risk)
d. Scopolamine: 1 patch behind the ear (72 hours if motion sick, 24 hours post op removed)
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