Mesoridazine is a piperidine

Piperidine

Piperidine is an organic compound with the molecular formula 5NH. This heterocyclic amine consists of a six-membered ring containing five methylene units and one nitrogen atom...

 neuroleptic drug belonging to the class of drugs called phenothiazine

Phenothiazine

Phenothiazine is an organic compound that occurs in various antipsychotic and antihistaminic drugs. It has the formula S2NH. This yellow tricyclic compound is soluble in acetic acid, benzene, and ether. The compound is related to the thiazine-class of heterocyclic compounds...

s, used in the treatment of schizophrenia

Schizophrenia

Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...

. It is a metabolite of thioridazine

Thioridazine

Thioridazine is a piperidine typical antipsychotic drug belonging to the phenothiazine drug group and was previously widely used in the treatment of schizophrenia and psychosis...

. The name is partially derived from the MEthyl-SulfOxy group in the structure.

It has central antiadrenergic, antidopaminergic, antiserotonergic and weak muscarinic anticholinergic effects.

Serious side effects include akathisia

Akathisia

Akathisia, or acathisia, is a syndrome characterized by unpleasant sensations of inner restlessness that manifests itself with an inability to sit still or remain motionless...

, tardive dyskinesia

Tardive dyskinesia

Tardive dyskinesia is a difficult-to-treat form of dyskinesia that can be tardive...

 and the potentially fatal neuroleptic malignant syndrome

Neuroleptic malignant syndrome

Neuroleptic malignant syndrome is a life- threatening neurological disorder most often caused by an adverse reaction to neuroleptic or antipsychotic drugs...

.

Mesoridazine was withdrawn from the United States market in 2004 due to dangerous side effects, namely irregular heart beat and QT-prolongation of the electrocardiogram.

Chemistry

Mesoridazine (10-[2-(1-methyl-2-piperidyl)ethyl]-2-(methylsufinyl)phenothiazine) is synthesized by an analogous scheme to that seen already for thioridazine

Thioridazine

Thioridazine is a piperidine typical antipsychotic drug belonging to the phenothiazine drug group and was previously widely used in the treatment of schizophrenia and psychosis...

.

However, it is also synthesized by alkylating the acidic form of 2-methylthiophenothiazine -methylsulfonylphenothiazine- using 2-(2-chloroethyl)-1-methylpiperidine. 2-methylthiophenothiazine is initially acylated at the nitrogen atom using acetic anhydride

Acetic anhydride

Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula 2O. Commonly abbreviated Ac2O, it is the simplest isolatable acid anhydride and is a widely used reagent in organic synthesis...

, giving 10-acetyl-2-methylthiophenothiazine. The resulting acetyl derivative is further oxidized by hydrogen peroxide

Hydrogen peroxide

Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

 into 10-acetyl-2-methylsulfonylpenothiazine. Deacylation of this product in potassium carbonate

Potassium carbonate

Potassium carbonate is a white salt, soluble in water , which forms a strongly alkaline solution. It can be made as the product of potassium hydroxide's absorbent reaction with carbon dioxide. It is deliquescent, often appearing a damp or wet solid...

 methanol solution gives 2-methylsulfanylphenothiazine, which is alkylated by 2-(2-chlorethyl)-1-methylpiperidine in the presence of sodamide, affording the desired mesoridazine.

• J. Renz, G. Schwarb, (1960).