Products
Antiemetics are commercially available in the form of tablets, as melting tablets, as solutions (drops), and injectables, among others. They are also administered as suppositories because peroral administration is not possible. In many countries, the best-known antiemetics include domperidone (Motilium, generic) and meclozine, which, along with caffeine and pyridoxine, is contained in Itinerol B6.
Structure and properties
Antiemetics do not have a uniform chemical structure.
Effects
The agents (ATC A04) have antiemetic properties, meaning they are effective against nausea and vomiting. Some are additionally prokinetic, meaning they accelerate gastric emptying and promote gastrointestinal motility. The chemoreceptor trigger zone of the area postrema and the vomiting center in the brainstem are stimulated by various neurotransmitters. These include dopamine, histamine, acetylcholine, and serotonin. Antiemetics are antagonists at the corresponding receptors. So, for example, dopamine antagonists, antihistamines, anticholinergics and serotonin antagonists. Which transmitters are involved depends on the cause. Therefore, different agents are recommended depending on the therapeutic area (literature: Flake et al., 2004 and 2015):
- Motion sickness, dizziness: 1st generation antihistamines and anticholinergics.
- Gastrointestinal cause (gastroenteritis/gastrointestinal flu): dopamine antagonists, serotonin antagonists.
- Migraine: dopamine antagonists.
Indications
For the prevention and treatment of nausea and vomiting. For example, in gastrointestinal flu, dizziness, motion sickness, postoperative nausea and chemotherapy and radiotherapy. For the treatment of vomiting during pregnancy. However, not all agents are approved for this purpose.
Active ingredients
Dopamine antagonists:
- Domperidone (Motilium, generic).
- Metoclopramide (Paspertin, Primperan).
- Some neuroleptics are dopamine antagonists and are also used as antiemetics, e.g., phenothiazines such as thiethylperazine (off-label), chlorpromazine (off-label), and promethazine (off-label) or butyrphenones such as haloperidol (Haldol) and droperidol.
1st generation antihistamines: (selection).
- Dimenhydrinate (eg, Trawell).
- Diphenhydramine (e.g., Benocten, off-label).
- Meclozine (Itinerol B6)
- Dimetindene maleate drops (Feniallerg, off-label).
Phytopharmka and herbal agents:
- Ginger
- Cannabis
- Cannabinoids: dronabinol, nabilone (synthetic).
Vitamins:
- Vitamin B6 (pyridoxine)
Anticholinergics:
- Scopolamine (out of commerce in many countries for this indication).
Serotonin antagonists at the 5-HT3 receptor:
- Granisetron (Kytril, generics).
- Ondansetron (Zofran, generic).
- Palonosetron (Aloxi, generic).
NK1 receptor antagonists:
- Aprepitant (Emend)
- Fosaprepitant (Ivemend)
- Netupitant (Akynzeo)
- Rolapitant (Varubi)
Adjunct:
- Cortisone tablets such as dexamethasone.
- Benzodiazepines
Alternative medicine:
- Nux vomica
Contraindications and adverse effects.
Full precautions can be found in the drug label. Adverse effects depend on the substances used (see under the active ingredients and drug groups).
