Antiemetics are a group of drugs used to prevent or relieve nausea and vomiting.
Nausea and vomiting are caused by stimulation of the vomiting centre in the brain. Antiemetic drugs suppress signals to and from the vomiting centre. They are used to prevent or relieve nausea and vomiting due to motion sickness, migraine, Ménière's disease, and labyrinthitis. The drugs can also relieve the nausea and vomiting that often occur during treatment with anticancer drugs or after a general anaesthetic, and severe vomiting in pregnancy (see Hyperemesis).
If you need an antiemetic for any reason other than to prevent or relieve motion sickness, consult your doctor so that he or she can determine the cause and correct treatment of the vomiting. Do not take antiemetics during pregnancy except on the advice of a doctor.
|Antihistamines: Cyclizine, Meclozine, Promethazine||Phenothiazines: Perphenazine, Prochlorperazine, Trifluoperazine|
|Serotonin antagonists: Granisetron, Ondansetron||Other drugs: Domperidone, Hyoscine hydrobromide, Metoclopramide|
What are the types of antiemetic drugs?
The three main types of antiemetic are antihistamines, phenothiazines, and serotonin antagonists. Other common drugs include metoclopramide, domperidone, and hyoscine hydrobromide. Antiemetics are normally taken orally, but may be given by injection or as a suppository if vomiting is severe.
These drugs may be taken to ease nausea caused by Ménière's disease and labyrinthitis and to prevent motion sickness. Some types for motion sickness can be bought over the counter. Side effects include drowsiness, blurred vision, dry mouth, difficulty passing urine, and problems with coordination. The drugs may affect driving ability.
These drugs may be used to treat severe vomiting in pregnancy or vomiting caused by anaesthetics. Side effects include dizziness, restlessness, muscle spasms, and tremor.
Serotonin antagonists drugs
These drugs are used mainly to relieve severe vomiting caused by chemotherapy for certain types of cancer. Serotonin antagonists, such as granisetron and ondansetron, are extremely effective, and have made chemotherapy more tolerable than it was in the past. This type of drug is started shortly before chemotherapy begins and is continued for up to a few days after the final dose of chemotherapy drugs is given. Serotonin antagonists may be used to prevent vomiting after surgery under general anaesthesia and are given by injection immediately after an operation. They cause very few side effects.
Metoclopramide is used to relieve nausea and vomiting, such as that caused by chemotherapy or associated with migraine. Side effects include muscle spasms, especially of the face. Domperidone is prescribed mainly to relieve nausea and vomiting due to chemotherapy, radiotherapy, or emergency hormonal contraception. It is also available over the counter for the relief of nausea, dyspepsia, bloating, and abdominal discomfort after eating. Side effects are rare; they may include breast enlargement, reduced sex drive, and a rash. Hyoscine hydrobromide may be prescribed as a skin patch to relieve motion sickness; it is also available over the counter as tablets. Side effects may include dry mouth, drowsiness, difficulty passing urine, and dizziness.
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