The anti-vomiting medications are also known as antiemetics. Vomiting is a completely natural defense reflex of our body and it is also a symptom of many diseases. Antiemetics are used in case of severe vomiting, which threatens the body by possible disruption of the internal environment and dehydration, or in situations where the vomiting is undesirable (for example in chemotherapy of tumor diseases or in trivial motion sickness in vehicles).
Drugs used to control vomiting belong to many pharmacological groups and they often have other effects besides the control of nausea and vomiting. The principle of the effect is usually inhibition of some parts of the pathway, which leads to irritation of the vomiting reflex centers in the brain. This includes inhibition of substances such as serotonin, dopamine, acetylcholine and histamine.
It is very difficult to give a comprehensive overview of these drugs. Most of them have relatively wide effects. I would like to mention rather those medicaments that are frequently used in everyday life, in internal medicine and related fields.
Drugs in this group block cell receptors for a substance known as histamine. They are primarily used in treatment of allergic reactions, but they also have antiemetic effect. Quite commonly prescribed substance moxastin is used in prevention and therapy of motion sickness. Antihistamines have also mild sedative effect.
I would like to mention this substance separately. It is an analogue of histamine. Betahistine stimulates certain receptors for histamine, but suppresses others. Its effect concentrates in the inner ear, which contains the organ of balance and movement. Betahistine has a great importance in neurology where it is used to treat dizziness, nausea and vomiting in patients with Meniere's disease.
These drugs block dopamine receptors, thus inhibiting the nausea. This group includes a number of medicaments, including some antipsychotics (psychiatric drugs). In practical medicine, we frequently use two prokinetic agents - metoclopramid and itopride. Prokinetics improve the motility of the digestive tract and thanks to their anti-dopamine effect, they also act as antiemetics. Therefore, they are great in situations where the nausea (and vomiting) occur due to decreased motility of the digestive tube. The group of dopamine antagonists also includes the widely used thiethylperazine, which is used in form of intravenous injections and suppositories.
This group of compounds blocks acetylcholine receptors. Relatively known plant alkaloid scopolamine belongs among these substances. However, it is not used in modern medicine due to its side effects on the user's psyche and self-control. Scopolamine has been abused in interrogations as the so-called "truth serum".
"Medicinal marijuana" may be legally prescribed only in certain countries in the world. It is used for example in patients with malignant diseases. Cannabis has not only anti-vomiting effect, but it also mild sedative and antidepressant.
Setrons are modern and highly effective group of drugs that have a strong effect against vomiting. The drugs block certain nerve receptors for serotonin (5-HT3 receptors). They are used against severe forms of vomiting, especially when it is related to treatment of malignant diseases.
The widely used anti-inflammatory drugs also suppress the nausea and vomiting. The mechanism of this effect is, however, not entirely clear.