Antiemetics - Antiemetics Drugs

Generality

Antiemetic 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 constitutes a symptom deriving from an underlying condition, which may or may not be pathological (gastrointestinal irritation, motion sickness, hormonal imbalances, migraines, metabolic disturbances, etc.), or which occurs as a side effect of some types of drugs (as occurs, for example, in the case of anticancer chemotherapy).
It goes without saying that this disorder can negatively affect the patient's life.
It therefore appears clear that the use of anti-emetic drugs is absolutely necessary to relieve patients affected by this disorder; it being understood that, in any case, the primary cause that triggered the vomiting must be identified and adequately managed. , whatever it is.
The main classes of antiemetic drugs used in therapy will be briefly described below.

Dopaminergic antagonists

Dopaminergic antagonists are antiemetic drugs that exert their activity through the antagonization of dopaminergic D2 receptors, present at the level of the Chemoreceptor Trigger Zone (more simply defined as CTZ).

The CTZ detects the emetogenic substances present in the organism and sends the information to the vomiting center, 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 "antagonist action against 5-HT3 receptors and an" agonist action against 5-HT4 type receptors present in the intestine. It is precisely the "interaction with this" last type of receptors that also gives these drugs a "prokinetic type of activity.
The main side effects that can occur following the use of antiemetics with dopaminergic antagonist action derive from the passage of these same drugs at a central level and consist of: fatigue, restlessness and movement disorders. Domperidone, however, is not able to crossing the blood brain barrier, therefore, causes fewer undesirable effects than other active ingredients of the same class.

Serotonergic antagonists

The active ingredients belonging to this class of antiemetic drugs exert their action by antagonizing the 5-HT3 serotoninergic receptors, present both centrally in the CTZ, and peripherally in the gastrointestinal tract.
This category includes ondansetron (Zofran®), granisetron (Sancuso®, Kytril®) and tropisetron (Navoban®).
These drugs are mostly used in the prevention and treatment of nausea and vomiting induced by anticancer chemotherapy and radiotherapy, as well as post-operative nausea and vomiting.
The main undesirable effects that may occur following treatment with antiemetics with 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 specifically, the antivomiting action of this active principle is exerted through the antagonization of the muscarinic receptors present at the level of the vestibular apparatus and of the nucleus of the solitary tract.
Generally, for the prevention of symptoms of motion sickness, scopolamine is used in the pharmaceutical form of a transdermal patch.
The main side effects that can occur following the use of antiemetics with antimuscarinic action are dry mouth, drowsiness and mydriasis.

Antihistamines

Antiemetic drugs with antihistamine action exert their activity through the antagonization of the receptors for histamine H1 present at the level of the vestibular nuclei, the nucleus of the solitary tract and the dorsal motor nucleus of the vagus.
Antiemetics belonging to this class are mainly used 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 group of antiemetics.
The main undesirable effects that may occur during the use of this type of anti-emetic drugs are: headache, loss of appetite and sleepiness.

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 much so that their use has obtained official approval for the prevention and treatment of nausea and vomiting, especially if associated with movement sickness.
In any case, to obtain more information about the uses of natural antiemetics, it is advisable to consult the "dedicated article" Nausea and vomiting - Herbal medicine ".


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