Dopamine is a neurotransmitter that acts primarily in the central nervous system and peripheral nervous system, although receptors for dopamine are also found in the blood vessels and in the kidney. Under normal conditions, there is a balance in the activity of dopamine and other neurotransmitters. Medications that block dopamine are used to treat conditions that result from a relative excess of dopamine acting in the central or peripheral nervous system. Dopamine blockers are prescribed mainly as antipsychotics, antiemetics and antidepressants.
Antipsychotic Medications
Dopamine blockers are most commonly prescribed in the treatment of psychosis, or schizophrenia. Schizophrenia is a serious condition resulting from a relative excess of dopamine in certain areas of the central nervous system. Antipsychotic medications represent the largest group of dopamine blockers. Examples include risperidone, or Risperdal; clozapine, or Clozaril; and olanzapine, or Zyprexa. The Mayo Clinic reports that side effects of these medications include weight gain, diabetes and high cholesterol.
Antiemetic Medications
A few dopamine blockers have strong antiemetic properties. These medications may be prescribed for cancer patients suffering chemotherapy-induced nausea. Powerful anticancer drugs used in chemotherapy are sometimes administered intravenously. When these drugs enter the bloodstream and circulate through the brain, they irritate certain chemically sensitive areas and trigger a vomiting reflex. Under normal conditions, vomiting is a protective reflex that causes the body to expel poisonous substances that might have been consumed. In the case of intravenously administered medications, however, the nausea is a side effect of the chemical irritation of the brain. Cancer Focus, an online resource for cancer patients, notes that dopamine blockers like metoclopromide, or Reglan, may offer relief for these patients.
Antidepressive Medications
Amoxapine, or Ascedin, is a dopamine blocker used in treating depression. It is a member of a class of drugs called triclyclic antidepressants, or TCAs. The MedlinePlus website reports that, although effective, frequent and sometimes serious side effects prevent amoxapine from being a first-line treatment.
