Active Ingredients

Thioridazine – Effect, Application & Risks


The active ingredient thioridazine is a neuroleptic . It can be used to treat schizophrenia and other mental illnesses.

What is thioridazine?

The antipsychotic thioridazine is part of the neuroleptic drug group. From a chemical point of view, it is one of the phenothiazines and is used as a low-potency neuroleptic.

Thioridazine is used to treat chronic forms of schizophrenia and other psychoses that are associated with states of excitement and psychomotor restlessness. As a rule, however, the drug is only used if no treatment success can be achieved with other drugs.

Thioridazine was patented in 1966 by the Swiss pharmaceutical company Sandoz, which is now part of Novartis AG. At that time, thioridazine was given the product name Melleril®. It is currently used as a generic drug .

The active ingredient is usually used as a tartrate or water-soluble hydrochloride. However, Melleril was withdrawn from the market in the United States of America and Europe by its largest manufacturer, Novartis, because it can cause dangerous cardiac arrhythmias .

Pharmacological action

Neuroleptics are used to treat schizophrenia. They have sedative and antipsychotic properties. The psychological disorders associated with schizophrenia are primarily caused by messenger substances such as serotonin and dopamine . For this reason, an inhibition of the corresponding receptors within the central nervous system is necessary. For this purpose, the serotonin or dopamine receptors are bound using different drugs. In this way they regulate the influence of the messenger substances as antagonists on the psyche of the patient.

Dopamine antagonists also include thioridazine. The mode of action of the drug is based on blocking dopamine receptors, which in turn has an inhibitory effect on the effects of dopamine. In addition, the neuroleptic suppresses the further release and reproduction of dopamine. However, the sedative effect of thioridazine is significantly stronger than its antipsychotic properties.

Low-potency neuroleptics such as thioridazine are not suitable for the sole therapy of psychoses. At a higher dosage, other receptors such as histamine receptors, adreno receptors and MACh receptors are activated, which in turn triggers increased side effects.

Recent research in India revealed a hitherto unknown effect of thioridazine. The neuroleptic proved to be successful against highly resistant bacterial strains of the Mycobacterium tuberculosis type , since the active ingredient also has antimicrobial properties. Furthermore, thioridazine can be used as a functional inhibitor of acid sphingomyelinase (FIASMA).

Medical Application & Use

Thioridazine is given to treat schizophrenia. The drug is used to combat psychoses, personality disorders , hallucinations and delusions . Thioridazine is also suitable for the treatment of states of excitement. However, the neuroleptic is usually only used as an accompanying drug or as an alternative when the usual drugs fail.

Thioridazine may also be suitable for the treatment of tuberculosis . However, approval for this purpose has not yet been granted.

If the neuroleptic is dosed according to the instructions, it is generally considered to be well tolerated. It is usually taken in the form of film-coated tablets. A liquid dosage form is also available for seniors.

Risks & side effects

Taking thioridazine can cause unwanted side effects. The most common side effects include drowsiness , dry mouth , dizziness , blurred vision , fluctuations in blood pressure and nasal congestion . In women, milk can sometimes flow from a non-lactating breast.

Other conceivable side effects include twitching , cramps , tremors , disturbances in motor functions , muscle rigidity , restlessness , pale face , allergic skin reactions, hives , sensitivity to light , a swollen parotid gland , an increase in body temperature , problems breathing and painful permanent erections of the penis without sexual motivation occurs.

In addition, the affected persons are often unable to sit still. In rare cases, depression , nightmares , neuroleptic syndrome , circulatory problems , intestinal obstruction , impaired consciousness or a coma also occur . In the worst case, it can even lead to the sudden death of the patient.

If there is hypersensitivity to thioridazine or if the patient suffers from pronounced cardiac arrhythmias or severe sensitivity to light, the use of the neuroleptic must be avoided. A combination with drugs that inhibit the cytochrome P4502D6 isoenzyme is also not permitted. These can be beta- blockers , tricyclic antidepressants, or serotonin reuptake inhibitors such as paroxetine or fluoxetine .

Precise studies on the use of thioridazine during pregnancy are not available. However, it was determined that the neuroleptic can penetrate the placenta . For this reason, a careful assessment of the risk and benefit is recommended before taking it.

In the last part of pregnancy there is a risk of side effects for the baby. These become noticeable through breathing difficulties, tremors, disturbances in the intake of food or drowsiness. In addition, thioridazine can penetrate breast milk , which also carries the risk of side effects in the child. Therefore, if thioridazine therapy is necessary, breastfeeding should be stopped beforehand . In children, thioridazine is only used if no other suitable medication is available.

The simultaneous administration of thioridazine and other drugs can lead to disruptive interactions. For example, the beta-blocker propranolol , the blood pressure medication pindolol and antidepressants such as fluvoxamine significantly slow down the metabolism with thioridazine. As a result, there is a risk of cardiac conduction disturbances , which in turn lead to serious cardiac arrhythmias.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.