phenothiazine

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phenothiazine

(fē'nəthī`əzĭn), any one of a class of drugs used to control mental disorders. Phenothiazines, along with other antipsychotic, or neuroleptic, drugs are used for such disorders as schizophrenia, paranoia, mania, psychosis resulting from mental deficiency, some forms of senility, hyperactivity in children, and even severe anxietyanxiety,
anticipatory tension or vague dread persisting in the absence of a specific threat. In contrast to fear, which is a realistic reaction to actual danger, anxiety is generally related to an unconscious threat.
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. Phenothiazines reduce psychiatric disorders without causing addiction or euphoria; sedation usually only occurs in the early stages of drug therapy. The most widely used phenothiazine, chlorpromazinechlorpromazine
, one of a group of tranquilizing drugs called phenothiazines that are useful in halting psychotic episodes. Chlorpromazine, sold under the trade name Thorazine, is often used to reduce the severe anxiety and agitation and the overactivity of some forms of schizophrenia.
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 (Thorazine), is prescribed for overactive schizophrenics; trifluoperazine (Stelazine) is used for inhibited and withdrawn schizophrenics. Typically, when a phenothiazine is taken over long periods of time, the frequency of recurring schizophrenic episodes decreases. Other phenothiazines are used in anesthesia and to control itching. Although many patients on phenothiazines and other neuroleptics show marked improvement, these drugs, when used over long periods of time, are fairly toxic. Parkinsonism (see Parkinson's diseaseParkinson's disease
or Parkinsonism,
degenerative brain disorder first described by the English surgeon James Parkinson in 1817. When there is no known cause, the disease usually appears after age 40 and is referred to as Parkinson's disease; a number of genes have
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) is a well-known side effect. Some patients experience severe reduction of motor activity, abnormal skin pigmentation, and visual impairment. Chlorpromazine therapy is associated with jaundicejaundice
, abnormal condition in which the body fluids and tissues, particularly the skin and eyes, take on a yellowish color as a result of an excess of bilirubin. During the normal breakdown of old erythrocytes (red blood cells), their hemoglobin is converted into bilirubin.
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. Because many phenothiazines are potent anti-emetics, i.e., they control vomitingvomiting,
ejection of food and other matter from the stomach through the mouth, often preceded by nausea. The process is initiated by stimulation of the vomiting center of the brain by nerve impulses from the gastrointestinal tract or other part of the body.
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, they may mask symptoms of toxic drug overdosage or of pathological disorders such as brain tumors. Phenothiazines also cause a disorder called tardive dyskinesia, which consists of bizarre muscular movements such as lip smacking and abnormal postures. It occurs in patients who have been given the drug for long periods of time. See also psychopharmacologypsychopharmacology
, in its broadest sense, the study of all pharmacological agents that affect mental and emotional functions. The term is usually applied more specifically to the study and synthesis of drugs used in the control of psychiatric illnesses, namely the
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.

phenothiazine

[′fē·nə′thī·ə‚zēn]
(organic chemistry)
C12H9N A yellow, crystalline compound, forming rhomboid leaflets or diamond-shaped plates, obtained from toluene or butanol solution; soluble in hot acetic acid, benzene, and ether; used as an insecticide and in pharmaceutical manufacture.