drugs

Antiemetics - Antiemetic Drugs

Generality

Anti-emetic drugs are medicines that are used in the treatment of vomiting and nausea of ​​various origins and nature.

In reality, vomiting is not a real disease, but it is a symptom deriving from an underlying condition, which may or may not be pathological (gastrointestinal irritation, motion sickness, hormonal imbalance, migraine, metabolism disorders, etc.), or which arises as a side effect of some types of drugs (as happens, for example, in the case of anticancer chemotherapy).

It is not necessary to underline how this disturbance can negatively affect the patient's life.

It therefore appears clear that the use of antiemetic drugs is absolutely necessary to relieve the patients affected by this disorder; it being understood that, in any case, the primary cause that triggered the vomit must be identified and adequately managed, whatever it may be.

The main classes of anti-emetic drugs used in therapy will be briefly described below.

Dopaminergic antagonists

Dopaminergic antagonists are anti-emetic drugs that exert their activity through the antagonization of D 2 dopaminergic receptors, present at the level of the Chemoreceptor Trigger Zone (more simply defined as CTZ).

The CTZ detects the emetogenic substances present in the body and sends the information to the center of the vomit, modulating its activity.

Chlorpromazine (Largactil®, Prozin®), haloperidol (Haldol®, Serenase®), droperidol, metoclopramide (Plasil®) and domperidone (Peridon®) belong to this class of antiemetic drugs.

Some of these active ingredients (such as, for example, metoclopramide and domperidone) have a certain affinity for serotonergic receptors. More specifically, they exert an antagonistic action against 5-HT 3 receptors and an agonist action against 5-HT 4 type receptors present in the intestine. It is precisely the interaction with the latter type of receptors that gives these drugs also a prokinetic type of activity.

The main side effects that may occur following the use of anti-emetic substances with a dopaminergic antagonist result from the passage of these same drugs centrally and consist of: fatigue, restlessness and movement disorders. Domperidone, however, is not able to cross the blood-brain barrier, therefore, it causes fewer undesirable effects than the other active ingredients of the same class.

Serotoninergic antagonists

The active ingredients belonging to this class of anti-emetic drugs exert their action by antagonizing the serotoninergic receptors of the 5-HT 3 type, present both at the central level in the CTZ, and at the peripheral level in the gastrointestinal tract.

This category includes ondansetron (Zofran®), granisetron (Sancuso®, Kytril®) and tropisetron (Navoban®).

These drugs are mainly used in the prevention and treatment of nausea and vomiting induced by cancer chemotherapy and radiotherapy, as well as post-operative nausea and vomiting.

The main side effects that can occur, following treatment with antiemetics with a dopaminergic antagonist action, are drowsiness, asthenia, headache and constipation.

antimuscarinics

Antimuscarinics are used for the prevention and treatment of nausea and vomiting caused by motion sickness (or motion sickness, if you prefer).

Scopolamine (Transcop®) belongs to this class of antiemetics. More in detail, the antivomited action of this active principle is exercised through the antagonization of muscarinic receptors present at the level of the vestibular apparatus and of the solitary tract nucleus.

Generally, for the prevention of motion sickness symptoms, scopolamine is used in the pharmaceutical form of a transdermal patch.

The main side effects that can occur following the use of anti-emetics with antimuscarinic action are dry mouth, drowsiness and mydriasis.

Antihistamines

Anti-emetic drugs with an antihistamine action exert their activity through the antagonization of histamine H 1 receptors present at the level of the vestibular nuclei, of the solitary tract nucleus and of the dorsal motor nucleus of the vagus.

Antiemetics belonging to this class are used above all in the prevention and treatment of nausea and vomiting caused by motion sickness, but also in the treatment of nausea and vomiting associated with Ménière's syndrome.

Dimenhydrinate (Xamamina®, Travelgum®) belongs to this antiemetic group.

The main side effects that can occur during the use of this type of anti-emetic drugs are: headache, loss of appetite and drowsiness.

Natural antiemetics

In phytotherapy there are several plants that are used for their potential antiemetic activity. Among these, the most prominent plant is certainly ginger. In fact, the gingerols and shogaols contained in its rhizome possess interesting anti-emetic properties, so that their use has obtained official approval for the prevention and treatment of nausea and vomiting, especially if associated with motion sickness.

However, to get more information about the uses of natural antiemetics, we recommend consulting the article "Nausea e vomito - Erboristeria".