Dopamine antagonists Dopamine antagonists, such as metoclopramide and prochlorperazine, work by blocking dopamine receptors in the brainstem...
Dopamine antagonists
Dopamine antagonists, such as metoclopramide and prochlorperazine, work by blocking dopamine receptors in the brainstem, which prevents the stimulation of the vomiting center and reduces nausea and vomiting. These drugs are effective for preventing and treating nausea and vomiting caused by chemotherapy and radiation therapy, as well as postoperative nausea and vomiting.
Dopamine antagonists are a class of drugs that work by blocking dopamine receptors in the brain. They are commonly used as anti-emetics to prevent or alleviate nausea and vomiting. Dopamine antagonists such as metoclopramide and prochlorperazine are effective for preventing and treating nausea and vomiting caused by chemotherapy and radiation therapy, as well as postoperative nausea and vomiting. They work by blocking dopamine receptors in the brainstem, which prevents the stimulation of the vomiting center and reduces nausea and vomiting.
Classification or Examples:
Common dopamine antagonists used as anti-emetics include
- metoclopramide and
- prochlorperazine.
Common brand names of above drugs in the USA and Pakistan:
USA:
- Metoclopramide: Reglan
- Prochlorperazine: Compazine
Pakistan:
- Metoclopramide: Maxolon, Reglan
- Prochlorperazine: Stemetil
Mechanism of Action:
Dopamine antagonists work by blocking dopamine receptors in the brainstem, which reduces the stimulation of the vomiting center and reduces nausea and vomiting.
Nausea and vomiting are controlled by the brain's vomiting center, which is located in the brainstem. This center receives signals from various parts of the body, including the inner ear, the digestive tract, and the brain itself. When these signals suggest that something is wrong, such as an infection or a toxin, the vomiting center can trigger nausea and vomiting as a protective response.
One of the key neurotransmitters involved in this process is dopamine. Dopamine is a chemical messenger that helps to transmit signals between nerve cells in the brain. When dopamine is released in the brain, it can bind to dopamine receptors in the vomiting center and cause nausea and vomiting.
Dopamine antagonists are a class of drugs that can block dopamine receptors in the vomiting center. By doing so, they can reduce the stimulation of this center and reduce the likelihood of nausea and vomiting. Metoclopramide is a dopamine antagonist that is commonly used to treat nausea and vomiting associated with chemotherapy or surgery. It works by blocking dopamine receptors in the vomiting center, which can help to reduce nausea and vomiting. Similarly, prochlorperazine and haloperidol are other dopamine antagonists that can be used for this purpose.
Pharmacokinetics:
Metoclopramide is rapidly absorbed from the GI tract and has a half-life of 4-6 hours. It is primarily metabolized in the liver and excreted in the urine. Prochlorperazine is also rapidly absorbed from the GI tract and has a half-life of 6-8 hours. It is primarily metabolized in the liver and excreted in the urine and feces.
Indications:
Dopamine antagonists are indicated for the prevention and treatment of nausea and vomiting caused by chemotherapy and radiation therapy, as well as postoperative nausea and vomiting.
Side Effects:
Common side effects of dopamine antagonists include drowsiness, dizziness, headache, dry mouth, constipation, and diarrhea. Long-term use of these drugs may cause tardive dyskinesia, a movement disorder characterized by repetitive involuntary movements of the face and limbs.
ADRs:
Rare but serious adverse reactions associated with dopamine antagonists include neuroleptic malignant syndrome, a potentially life-threatening condition characterized by fever, muscle rigidity, and autonomic dysfunction, and agranulocytosis, a severe reduction in white blood cells that can lead to serious infections.
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