| Situation | Associated neurotransmitters | Recommended antiemetic |
| Cancer patients | ||
| No definite etiology (not related to chemotherapy or radiation, constipation, central nervous system disease, metabolic abnormalities/drugs, or bowel obstruction) | Dopamine, serotonin (type 3 receptor [5HT3] and type 4 receptor [5HT4]), acetylcholine (muscarinic) | First line: Metoclopramide 10 mg every 4 hours orally or subcutaneously; if insufficient relief with intermittent dosing, may switch to an intravenous or subcutaneous continuous infusion (starting at 30 to 40 mg per 24 hours, increasing to 2.5 to 5 mg/hour infusion [maximum 60 to 120 mg/day]) if needed for relief. A nasal formula is also available, dosed as 1 spray (15 mg) in 1 nostril 4 times daily (30 minutes prior to each meal and at bedtime). Second line: Add 5HT3 receptor antagonist* or substitute dopamine receptor antagonist (chlorpromazine 10 to 25 mg every 4 to 8 hours orally, 10 to 25 mg every 3 to 4 hours intravenously, or 25 mg initially, followed by 10 to 25 mg every 3 to 4 hours intramuscularly; prochlorperazine 5 to 25 mg every 6 to 8 hours orally, intramuscularly, or rectally (where available); or haloperidol 0.5 to 2 mg every 6 to 8 hours orally, intravenously, or subcutaneously) or olanzapine 2.5 to 5 mg every 12 hours orally or sublingually. |
| Chemotherapy-induced nausea and vomiting (CINV) | 5HT3, neurokinin-1 | First line:
|
| Radiation therapy-induced nausea and vomiting | 5HT3, dopamine | First line:
|
| Gastroparesis | Dopamine, 5HT3, 5HT4, acetylcholine (muscarinic) | First line: Metoclopramide 5 to 10 mg 4 times daily intravenously, orally, or subcutaneously. A nasal formula is also available, dosed as 1 spray (15 mg) in 1 nostril 4 times daily (30 minutes prior to each meal and at bedtime). Second line: Mirtazapine or erythromycin. Third line: Domperidone (limited availability in the United States) or cisapride (limited availability in the United States). |
| Bowel obstruction (inoperable)◊ | Dopamine, somatostatin, acetylcholine (muscarinic) | First line: Haloperidol 0.5 to 2 mg every 6 to 8 hours orally, intravenously, or subcutaneously and titrate up to 20 mg/day if needed; also add dexamethasone 4 mg every 12 hours intravenously or subcutaneously; and octreotide 0.1 mg every 8 hours intravenously or subcutaneously up to 0.3 mg every 8 hours, depending on response; scopolamine (hyoscine) butylbromide (where available) 20 mg SC followed by 60 mg per day as a continuous SC infusion; or transdermal scopolamine. Second line: Chlorpromazine, prochlorperazine, or cyclizine subcutaneously (not chlorpromazine), rectally (only for prochlorperazine, where available), or intravenously. |
| Nausea due to intracranial malignancy (primary or secondary brain tumor) | Unknown | First line: Dexamethasone 10 mg loading dose, followed by 4 mg every 6 hours or 8 mg every 12 hours, orally or intravenously. |
| Nausea due to non-cancer conditions | ||
| Kidney failure | Haloperidol (decrease dose by 50%). | |
| Liver failure | Metoclopramide at 60 mg per 24 hours appears to be safe and does not increase sedation in mild encephalopathy. | |
| Chronic obstructive pulmonary disorder (COPD) | No specific recommendations, but in view of association with GERD, a prokinetic such as metoclopramide is reasonable. | |
| Heart failure | No specific recommendation; however, use ondansetron or metoclopramide with caution. | |
| Human immunodeficiency virus (HIV) | Often related to antiretroviral medication. No specific antiemetic recommendation; however, patients with HIV on metoclopramide may be at increased risk of EPS. Consider the cannabinoid dronabinol in patients who also have a poor appetite (initial dose 2.5 mg twice daily before lunch and dinner and titrate up to a maximum of 20 mg/day). | |
GERD: gastroesophageal reflux disease; EPS: extrapyramidal symptoms.
* 5HT3 receptor antagonists: granisetron, ondansetron, palonosetron, dolasetron, tropisetron, ramosetron.
¶ Neurokinin-1 antagonists: aprepitant, fosaprepitant.
Δ Dopamine receptor antagonists: chlorpromazine, haloperidol, prochlorperazine.
◊ Metoclopramide might be helpful if the bowel obstruction is partial. Do not use in patients with a confirmed or suspected complete mechanical obstruction.
