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THE RATIONAL USE OF ANTIEMETICS First broadcast on www.provet.co.uk |
This information is provided by Provet for educational purposes only.
You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.
There are numerous occasions when the use of an anti-emetic drug is indicated in veterinary practice. However, these drugs have different modes of action and understanding these is important so that the most appropriate drug can be selected for use under specific clinical circumstances.
Antiemetic drugs have different modes of action on the complex sequence of events involved in the vomiting reflex - from visceral receptors to the chemoreceptor trigger zone (CRTZ) in the brain.
Basically there are 2 pathways leading to vomiting :
- A bloodborne (humoral) route - uraemia, glycosides, apomorphine, other toxins.
- A neural route - vagosympathetic, chemoreceptor trigger zone, vestibular or cerebrocortical stimulation
The following table classifies the most frequently used anti-emetics and their uses. Some drugs have more than one mode of action.
| ANTI-EMETIC TYPE | DRUGS | ACTION |
| 5-HT3 serotonergic antagonists. | Metoclopramide, Ondansetron | Prevent vomiting due to chemotherapy and radiation |
| 5-HT4 serotonergic antagonists | Cisapride | Promotes gastric emptying by activation of receptors |
| a2 adrenergic antagonists | Chlorpromazine, Prochlorperazine, Yohimbine | Prevent vomiting due to activation of the CRTZ or emetic centre |
| D2 dopaminergic antagonists | Butyrophenones, Domperidone, Metaclopramide, Phenothiazines Trimethobenzamine, | Counteract mild emesis due to chemotherapy, uraemia, septicaemia and gastrointestinal disorders including pancreatitis. |
| H2 histaminergic antagonists | Diphenhydramine Dimenhydrinate | Motion sickness |
| M1 cholinergic antagonists | Chlorpromazine, Scopolamine | Motion sickness |
| Motilin agonists | Erythromycin (low dose) | Facilitates gastric emptying during fasting |
| Opiate antagonists | Butorphanol | Prevent vomiting due to some types of chemotherapy (eg cisplatinum) |
Updated January 2016