Antipsychotic  

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An antipsychotic (or neuroleptic) is a tranquilizing psychiatric medication primarily used to manage psychosis (including delusions or hallucinations, as well as disordered thought), particularly in schizophrenia and bipolar disorder. A first generation of antipsychotics, known as typical antipsychotics, was discovered in the 1950s. Most of the drugs in the second generation, known as atypical antipsychotics, have been developed more recently, although the first atypical antipsychotic, clozapine, was discovered in the 1950s and introduced clinically in the 1970s. Both generations of medication tend to block receptors in the brain's dopamine pathways, but antipsychotic drugs encompass a wide range of receptor targets.

A number of harmful and undesired (adverse) effects have been observed, including lowered life expectancy, weight gain, enlarged breasts and milk discharge in men and women (hyperprolactinaemia), lowered white blood cell count (agranulocytosis), involuntary repetitive body movements (tardive dyskinesia), diabetes, an inability to sit still or remain motionless (akathisia), sexual dysfunction, a return of psychosis requiring increasing the dosage due to cells producing more neurochemicals to compensate for the drugs (tardive psychosis), and a potential for permanent chemical dependence leading to psychosis much worse than before treatment began, if the drug dosage is ever lowered or stopped (tardive dysphrenia).

Temporary withdrawal symptoms including insomnia, agitation, psychosis, and motor disorders may occur during dosage reduction of antipsychotics, and can be mistaken for a return of the underlying condition.

The development of new antipsychotics with fewer of these adverse effects and with greater relative effectiveness as compared to existing antipsychotics (efficacy), is an ongoing field of research.

History

The original antipsychotic drugs were happened upon largely by chance and then tested for their effectiveness. The first, chlorpromazine, was developed as a surgical anesthetic. It was first used on psychiatric patients because of its powerful calming effect; at the time it was regarded as a "chemical lobotomy". Lobotomy at the time was used to treat many behavioral disorders, including psychosis, although its effect was to markedly reduce behavior and mental functioning of all types. However, chlorpromazine proved to reduce the effects of psychosis in a more effective and specific manner than the extreme lobotomy-like sedation it was known for. The underlying neurochemistry involved has since been studied in detail, and subsequent antipsychotic drugs have been discovered by an approach that incorporates this sort of information.

The discovery of chlorpromazine's psychoactive effects in 1952 led to greatly reduced use of restraint, seclusion, and sedation in the management of agitated patients, and also led to further research that resulted in the development of antidepressants, anxiolytics, and the majority of other drugs now used in the management of psychiatric conditions. In 1952, Henri Laborit described chlorpromazine only as inducing indifference towards what was happening around them in nonpsychotic, nonmanic patients, and Jean Delay and Pierre Deniker described it as controlling manic or psychotic agitation. The former claimed to have discovered a treatment for agitation in anyone, and the latter team claimed to have discovered a treatment for psychotic illness.


Antipsychotics have long been known as neuroleptic drugs. The word neuroleptic was derived from the Template:Lang-el (neuron, originally meaning "sinew" but today referring to the nerves) and "λαμβάνω" (lambanō, meaning "take hold of"). Thus, the word means taking hold of one's nerves. This may refer to common side effects such as reduced activity, lethargy, and impaired motor control. Although these effects are unpleasant and in some cases harmful, they were at one time considered a reliable sign that the drug was working. The term "neuroleptic" is being abandoned in favor of "antipsychotic," which refers to the drug's desired effects. Typical antipsychotics have also been referred to as the major tranquilizers, because of their tendency to tranquilize and sedate. As with the term "neuroleptics," the term "major tranquilizers" is falling out of common and scientific use. The term "tranquilizers" now generally refers to drugs that are primarily intended to sedate—mostly the barbiturates and benzodiazepines, which were once referred to as the "minor tranquilizers."

Antipsychotics are broadly divided into two groups, the typical or first-generation antipsychotics and the atypical or second-generation antipsychotics. The typical antipsychotics are classified according to their chemical structure while the atypical antipsychotics are classified according to their pharmacological properties. These include serotonin-dopamine antagonists (see dopamine antagonist and serotonin antagonist), multi-acting receptor-targeted antipsychotics (MARTA, those targeting several systems), and dopamine partial agonists, which are often categorized as atypicals.





Unless indicated otherwise, the text in this article is either based on Wikipedia article "Antipsychotic" or another language Wikipedia page thereof used under the terms of the GNU Free Documentation License; or on original research by Jahsonic and friends. See Art and Popular Culture's copyright notice.

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