From the Guidelines
Dopamine receptors play a crucial role in nausea and vomiting, and blocking these receptors with dopamine antagonists is an effective strategy for managing nausea. The relationship between dopamine receptors and nausea is well-established, with dopamine receptors, particularly D2 receptors, playing a significant role in the chemoreceptor trigger zone (CTZ) of the brain, triggering the vomiting reflex when activated by dopamine 1.
Key Points to Consider
- Dopamine antagonists like metoclopramide and prochlorperazine are effective antiemetics that block D2 receptors, preventing dopamine from triggering nausea signals 1.
- For optimal management of nausea, these medications should be taken regularly rather than as needed, and treatment should continue for a sufficient duration to ensure symptoms are adequately controlled 1.
- Understanding the dopamine-nausea connection is essential, especially in patients with conditions like Parkinson's disease, who may experience nausea as a side effect of dopamine-increasing medications 1.
- The use of dopamine antagonists, such as metoclopramide (10mg orally or IV every 6 hours) and prochlorperazine (5-10mg orally every 6-8 hours or 25mg rectally twice daily), can be effective in managing nausea, but it's crucial to consider the potential side effects, including extrapyramidal symptoms due to dopamine blockade in movement-controlling brain regions 1.
Management of Nausea
- The management of nausea should involve a comprehensive approach, including the use of antiemetic agents that target different neuroreceptors, such as serotonin and dopamine receptors, to achieve a synergistic effect 1.
- In cancer patients, the incidence and severity of nausea and vomiting can be related to several factors, including the emetic risk of chemotherapy, patient variability, and the presence of other underlying conditions 1.
- A thorough assessment of the cause of nausea is essential to guide treatment and ensure the best possible care for patients experiencing nausea and vomiting 1.
From the FDA Drug Label
The antiemetic properties of metoclopramide appear to be a result of its antagonism of central and peripheral dopamine receptors Dopamine produces nausea and vomiting by stimulation of the medullary chemoreceptor trigger zone (CTZ), and metoclopramide blocks stimulation of the CTZ by agents like l‑dopa or apomorphine which are known to increase dopamine levels or to possess dopamine-like effects.
The relationship between dopamine receptors and nausea is that dopamine stimulates the medullary chemoreceptor trigger zone (CTZ), producing nausea and vomiting. Dopamine antagonists, such as metoclopramide, can block this stimulation and prevent nausea and vomiting 2.
From the Research
Dopamine Receptors and Nausea Relationship
- Dopamine receptor antagonists are useful antiemetic agents, commonly used to treat nausea and vomiting, particularly in palliative care patients 3, 4.
- These agents work by blocking dopamine receptors in the chemoreceptor trigger zone (CTZ) and improving gastrointestinal function 4.
- Dopamine antagonists, such as metoclopramide, have a unique mechanism of action, increasing lower esophageal sphincter pressure and gastric emptying rate, making them effective in treating nausea and vomiting associated with various conditions, including diabetic gastroparesis and chemotherapy 5.
- However, dopamine antagonists should be used with caution due to potential adverse effects, such as QTc prolongation, tardive dyskinesia, and increased risk of psychosis and death in patients with dementia 4, 6.
Clinical Applications and Considerations
- Dopamine receptor antagonists are indicated for treating nausea and vomiting in various clinical settings, including palliative care, migraine, and chemotherapy 3, 4, 7, 5.
- The choice of dopamine antagonist and dosage should be carefully considered, taking into account factors such as renal function, hepatic function, and age 4.
- Metoclopramide, a commonly used dopamine receptor antagonist, has a low risk of tardive dyskinesia, estimated to be around 0.1% per 1000 patient years, although high-risk groups, such as elderly females and patients with liver or kidney failure, should be monitored closely 6.