Dopamine is a signaling chemical--a neurotransmitter--that is used by various cells in the body to communicate with one another. The primary places in the body where dopamine is used are in the central nervous system, peripheral nervous system and in the blood vessels. These medications are used to treat conditions resulting from too much production of dopamine. The main uses for dopamine blockers are: anti-psychotics, anti-emetics (drugs used to treat nausea and vomiting) and anti-depressants.
The mainstay of dopamine blockers is treatment of schizophrenia. Anti-psychotic medications are the largest group of dopamine blockers on the market today. Clozapine (sold as Clozaril, Leponex) is a commonly prescribed anti-psychotic medication to treat this condition. Schizophrenia is a psychiatric condition resulting from a relative overproduction of dopamine in certain parts of the brain. Although there are side effects to treatment with these drugs, many patients have returned to a normal life thanks to this class of medications. (see Reference 1)
The anti-emetic properties of some dopamine blockers are exploited when treating the extreme nausea that accompanies chemotherapy in treatment of some cancers. The strong medications in the chemotherapy circulate through the entire body and irritate certain parts of the brain, which are sensitive to foreign chemicals in the bloodstream. Normally, the nausea is a protective reflex that would cause the body to expel anything poisonous that might have been consumed. In the case of chemotherapy, however, the drugs are delivered intravenously and the nausea is an unfortunate side effect. Treatment with some dopamine blockers like metoclopromide (Reglan) can bring relief in such cases. Other anti-emetic drugs that are dopamine antagonists include Domperidone, Haloperidol, Chlorpromazine and Alizapride. (see Reference 2)
The most famous dopamine blocker antidepressant is Wellbutrin. It is a commonly used antidepressant medication in modern psychiatric treatment protocols. Most often, Wellbutrin is used to treat major depressive disorder and seasonal affective disorder. (See Reference 3)