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Phenothiazine

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Phenothiazine, also called dibenzothiazine or thiodiphenylamine is a yellow or green crystalline compound soluble in hot acetic acid, benzene, and ether. It is a three-ring structure compound in which two benzene rings are joined by a sulfur and nitrogen atom at nonadjacent positions. It is obtained by fusing diphenylamine with sulfur.

It is a dibenzo derivative of thiazine, although thiazine itself is not used as a starting point in the manufacturing of this molecule.

It is a semi-volatile organic compound and environmental toxicant of concern to the United States Environmental Protection Agency.[1]

Overview

The phenothiazine structure occurs in various neuroleptic drugs, e.g. Chlorpromazine. The synthetic dye methylene blue, containing the structure, was invented in 1876. Phenothiazine was introduced by DuPont as an insecticide in 1935.[2] It is sometimes used as an antihelminthic in livestock. It is used as an industrial chemical in the manufacture of rubber additives.[3]

Phenothiazine pesticides work by affecting the nervous system of insects, inhibiting the breakdown of acetylcholine by disabling the enzyme acetylcholinesterase. Many of the side effects of phenothiazine neuroleptic antipsychotics are due to their anticholinergic blocking effects.[4]

Phenothiazine is also a potent alpha-adrenergic blocking agent.

Synonyms for the chemical phenothiazine

Dibenzoparathiazine Thiodiphenylamine; AFI-Tiazin; Agrazine; Antiverm; Biverm; Dibenzothiazine; Orimon; Thiodiphenylamine; Lethelmin; Souframine; Nemazene; Vermitin; Padophene; Fenoverm; Fentiazine; Contaverm; Fenothiazine; [5]

Phenothiazine-derivative drugs

The term "phenothiazines" is used to describe the largest of the five main classes of neuroleptic antipsychotic drugs. These drugs have antipsychotic and, often, antiemetic properties, although they may also cause severe side effects such as akathisia, tardive dyskinesia, extrapyramidal symptoms, and the rare but potentially fatal neuroleptic malignant syndrome as well as substantial weight gain.

Phenothiazines are used as inodilators in congestive heart failure, acting upon the type I calcium/calmodulin dependent phosphodiesterase.[6]

The phenothiazine class of neuroleptics are closely related to the thioxanthenes which are very similar pharmacologically.

There are three groups of phenothiazine antipsychotics, differing by their chemical structure and their pharmacological effects. They are the aliphatic compounds, the piperidines and piperazines. An aliphatic compound, piperidine or piperazine functional group is added to the phenothiazine molecule for the purpose of enhancing absorption and bioavailability of the phenothiazine chemical.

Group Autonomic Example Sedative Extrapyramidal side-effect
Aliphatic compounds
moderate Chlorpromazine (marketed as Thorazine, Chlor-PZ, Klorazine, Promachlor, Promapar, Sonazine, Chlorprom, Chlor-Promanyl, Largactil) strong moderate
Promazine (trade name Sparine) moderate moderate
Triflupromazine (trade names Stelazine, Clinazine, Novaflurazine, Pentazine, Terfluzine, Triflurin, Vesprin) strong moderate/strong
Levomepromazine in Germany and Methotrimeprazine in America (trade names Nozinan, Levoprome) extremely strong low
Piperidines strong Mesoridazine (trade name Serentil) strong weak
Thioridazine (trade names Mellaril, Novoridazine, Thioril) strong weak
Piperazines weak Fluphenazine (trade names Prolixin, Permitil, Modecate, Moditen) weak/moderate strong
Perphenazine (sold as Trilafon, Etrafon, Triavil, Phenazine) weak/moderate strong
Flupentixol (sold as Depixol, Fluanxol) moderate strong
Prochlorperazine (trade names Compazine, Stemetil)
Trifluoperazine (trade name Stelazine) moderate strong


References

Further reading