You are called to the ward at night because a patient with gastroenteritis is feeling nauseous.
- What medication could you offer her?
The sensation of nausea can result from several different pathophysiologic pathways. Understanding which pathway is involved in a given patient’s experience of nausea is important for selecting the appropriate anti-emetic. Medication options include:
- Ondansetron – serotonin antagonist
- Dimenhydrinate (Gravol) – anticholinergic/antihistamine
- Prochlorperazine – dopamine antagonist
- Metoclopramide – prokinetic
- What is your first choice medication in this case?
Nausea in this case is mediated through visceral stimulation by serotonin, which is caused by mucosal irritation. Ondansetron is a serotonin antagonist, and as such can be used as first-line treatment in this patient.
It is important to keep in mind that first-line anti-nausea medications should always be ordered on admission for any patient (unless there is a specific contraindication).
- What if your initial medication was not working?
Prochlorperazine is a dopamine antagonist, and can be used as second line treatment since dopamine is also implicated in visceral-mediated nausea.
Dimenhydrinate (Gravol) should be avoided when possible, especially in the elderly, due to its anticholinergic effects.
Flake ZA, Scalley RD and Bailey AG. Practical Selection of Antiemetics. Am Fam Physician. 2004, 69:1169-1174.