Phenothiazine Derivatives

Phenothiazine derivatives are nonselective, competitive D1 and D2 antagonists that block dopamine activity on corresponding receptor sites. In addition, their action is expressed by blocking a-adrenoreceptors, serotonine, cholinergic, nicotinic, and muscarinic receptors.

Phenothiazines exhibit a complex pharmacological range of action on the CNS and the peripheral nervous system. In addition, they act on the endocrine system.

Every compound of this series differs to a certain degree from the other in their qualitative, yet primarily quantitative characteristics. They all act on the CNS by causing moderate sedative and antiemetic effects, affecting thermoregulatory processes, skeletal muscle, endocrine system, and by potentiating action of analgesics.

This group of drugs is subdivided into three subgroups depending on the type of substitution on the nitrogen atom of the phenothiazine ring. The subgroups are: phenothiazines with an aliphatic side chain (chlorpromazine, promazine, triflupromazine), piperazine derivatives (acetophenazine, fluphenazine, perphenazine, prochlorperazine, trifluoperazine), and piperidines (mesoridazine, thioridazine).

Drugs of the first subgroup (with an aliphatic side chain), along with expressed antipsy-chotic action, differ in their ability to cause lethargy, sluggishness, and intellectual lethargy. The sedative action of these drugs exceeds activity of other drugs of the phe-nothiazine series.

Piperazine derivatives inherent presence of stimulatory components.Phenothiazines with an aliphatic side chain and piperidine substituents have more of a sedative effect than piperazine derivatives.

The nature of the substituent in the second position of the phenothiazine ring has an extremely important influence on the activity of these compounds; an acceptor group is preferred.

Phenothiazines have a diverse use in medicine. They are primarily used as antipsy-chotics. Despite the fact that they do not cure the disease, they reduce psychotic symptoms to a point where the patient is provided with a better sense of reality. Phenothiazines are sometimes used for relieving severe anxiety, especially in panic attacks caused by dependence on amphetamines or lycergic acid diethylamide (LSD). Phenothiazines are used for alleviating behavioral problems in children that do not respond to treatment of other agents. Phenothiazines are sometimes used during the preoperational period because they relieve anxiety, control nausea, hiccups, diarrhea, and also cause muscle relaxation.

Promazine: Promazine, 10-(3-dimethylaminopropyl)phenothiazine (6.1.1), is prepared by the alkylation of phenothiazine with 3-dimethylaminopropylchloride in the presence of sodium amide [1-3].

In psychiatric practice, promazine is used in minor cases of psychomotor excitement in schizophrenics, in paranoid and manic-depressive conditions, for neurosis, alcoholic psychosis, and others. It is sometimes used in anesthesiological practice. The most common synonyms are propazine, trilafon, sparine, permitil, and others.

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