Antiemetics

Nausea Causing Medications¶

MOA: Block serotonin receptors in the CNS and GI
- Works on GI tract primarily, but CNS/PNS also
- Used in gastroenteritis
- SE: Headache, constipation, diarrhea, dry mouth, fatigue, Serotonin Syndrome, QTc Prolongation
- CI: PKU, Hepatic Impairment
Ondansetron (Zofran)
- Dose: 4-8mg Oral, Sublingual, IV over 15 minutes
- SE: QTc Prolongation, Activating
Palonosetron (Aloxi)
- Dose: 0.25mg IV
- No QT prolongation, 40 hour half life, better than 8mg zofran
- SE: Activating
Dolasetron
Granisetron
- Oral, IV, Subcutaneous, Transdermal

Notes:
- Works on CNS (area postrema) and in the vestibular nucleus
- SE: QTc Prolongation
Diphenhydramine (Benadryl)
- 10-50mg per dose, up to 100mg per dose, 400mg per day
- Oral, IV, IM
- SE: QTc Prolongation
- CI: Acute asthma, GI obstruction, Closed angle glaucoma
Meclizine
- No QTc prolongation
Dimenhydrinate
- No QTc prolongation
Cyclizine
Mirtazapine (Remeron)
Hydroxyzine (Vistaril)
- Quick acting, short-term, anxiolytic, insomnia
- SE: sedation, dry mouth, constipation, urinary retention, blurry vision
  - QTc Prolongation

Prochlorperazine (Compazine)
- MOA: D2 antagonism ≥ H1 = M1
- Dose: 10mg IV
- Little to no QTc prolongation
- SE: Extrapyramidal SE, M1 activity
Chlorpromazine (Thorazine)
- MOA: D2 = H1 ≥ M1 ≥ 5HT3
- Dose: 25mg IV/IM
- SE: Extrapyramidal SE, QTc Prolongation, M1 activity
Promethazine (Phenergan)
- MOA: H1 ≥ M1 ≥ D2
- Dose: 12.5-25mg PO/IM
- SE: Extrapyramidal SE, QTc Prolongation, Most M1 activity

Droperidol
- MOA: D2 Antagonism ≥≥≥ H1
- Dose: 0.625-2.5 IV, IM
- SE: QTc Prolongation
Haloperidol
- MOA: D2 Antagonism ≥≥≥ H1
- Dose: 2-5 mg IV, Oral, IM
- SE: QTc Prolongation

Metoclopramide
- MOA: D2 ≥ 5-H3T antagonism, Cholinergic Agonism
- 10-20mg Oral, IV, IM
- SE: QTc Prolongation
Domperidone
- MOA: D2 antagonism
- Oral
- SE: QTc Prolongation, Headache, Xerostomia

MOA: M1 antagonism
Scopolamine
- Transdermal
- No QTc Prolongation
- SE: Xerostomia, Blurry Vision, Fatigue