Our increasing knowledge has resulted in achievements that have benefited patients in two primary ways. Firstly, drugs have been developed that are much more specific in their actions. For example, drugs such as olanzapine and risperidone act more specifically on particular receptors therefore greatly minimizing the unpleasant side effects associated with conventional drugs such as haloperidol. The second benefit has resulted from developing drugs that precisely target newly identified receptors. As discussed earlier, the re-uptake apparatus is a site of action for many antidepressants.
Antipsychotic drugs act primarily at receptors.
There are several receptor sites specifically for dopamine, which are classified into categories based on structural, pharmacological, and functional characteristics. The main target of the classic antipsychotic drugs is the D2 dopamine receptor. New research has identified the D4 dopamine receptor, which may have unique functions such as regulating the production of dopamine. The D4 receptor is of interest because it may be a site of action of clozapine. Consequently, efforts have been made to identify drugs that act exclusively on the D4 receptor.