There are different types of antipsychotics. They can be classified according to their time of onset (first or second generation; typical and atypical) and according to the class of drugs to which they belong.

In this article we will talk about one particular antipsychotic: mesoridazine, belonging to the phenothiazines (a group of antipsychotics) . We will know its characteristics, what it is used for and its therapeutic and adverse effects.

Antipsychotic drugs

Before we get into mesoridazine, which is an antipsychotic, let’s explain in a nutshell what exactly these drugs are. Antipsychotics are drugs, as their name suggests, that relieve psychotic symptoms, such as hallucinations or delusions . However, they are often used to treat other symptoms as well, such as excessive agitation or restlessness.

This is why they are often prescribed to people suffering from psychotic disorders (such as schizophrenia), but also to people suffering from confusion, delirium, agitation, movement disorders and tics (e.g. Gilles de la Tourette), etc.

Its mechanism of action involves a blockage of receptors for dopamine , which causes levels of this neurotransmitter to decrease (people with schizophrenia have been observed to have abnormally high levels of dopamine).

Specifically, antipsychotics block a receptor called D2, which affects four brain pathways: the mesolimbic, nigrostriatal, mesocortical and tuberoinfundibular pathways . Blocking these four pathways produces different adverse effects, but also the desired therapeutic effects (the latter by blocking the mesolimbic and mesocortical pathways).

Now, let’s talk about mesoridazine, a type of antipsychotic drug belonging to phenothiazines (a chemical compound).


Mesoridazine (brand name: Serentil) is an antipsychotic (neuroleptic) drug, used for the treatment of schizophrenia, to relieve symptoms such as hallucinations, delusions, and agitation.

Specifically, mesoridazine is a piperidine neuroleptic (a type of organic compound), and belongs to a class of drugs: phenothiazines. In turn, it is a metabolite of thioridazine (another typical piperidine antipsychotic drug).

On the other hand, it can be said that mesoridazine is not marketed worldwide today. It was withdrawn from the market in the United States in 2004 , due to its side effects, which proved to be dangerous.

Such effects included: irregular heartbeat and prolongation of the electrocardiogram QT interval. Note that the prolongation of the QT interval can generate ventricular arrhythmias in the patient.


The main indication for mesoridazine is schizophrenia . It is used, as we have seen, to treat its associated symptoms, which are: hallucinations, delusions and agitation.

Thus, mesoridazine is effective in treating psychotic symptoms, but also others such as agitation, restlessness or tension , which are more typical of anxiety disorders.

Brain-level effects

Mesoridazine has different effects on the brain: antidopaminergic effects (resulting in a decrease in dopamine), central antiadrenergic (decreased adrenaline), anti-serotoninergic (decreased serotonin) and muscarinic anticholinergic (the latter is weak).


We have seen that mesoridazine belongs to the phenothiazine class of drugs. Mesoridazine is included in this group along with other drugs, such as: piperacetazine, pipoptiazine, propericizine, sulforidazine and thioridazine.

But what exactly are phenothiazines? It is a chemical compound, yellowish/greenish in color. Its structure is formed by three rings; specifically, its tricyclic nucleus is formed by two benzene rings, a sulphur atom and a nitrogen atom .

Thus, phenothiazines are actually considered a group of antipsychotics. These in turn are divided into three subgroups (which differ in their chemical structure and pharmacological properties): the piperidines, the piperazines and the aliphatic compounds. The mesoridazine in particular belongs to the first group, the piperidines (as we have already seen).

Dosage and format

Mesoridazine is sold in different formats: injection, liquid concentrate and tablets. Generally, mesoridazine is taken in tablet format , but this will vary depending on the patient’s profile and needs.

Normally, it is recommended to take it concentrated in water or with orange juice. In case of taking mesoridazine in injection format, it is recommended to rest for at least half an hour after administration.

The doses must be prescribed by the doctor , who generally prescribes regular, daily doses. It is important not to stop taking mesoridazine (as well as most other drugs) suddenly, much less without consulting a specialist; doing so may worsen pre-existing symptoms.

Side effects

Like most drugs, mesoridazine also has side effects. The most common are: weight gain, restlessness, anxiety, constipation, headache, diarrhea, nausea, dizziness, vomiting and changes in appetite.

More serious effects

The effects mentioned are the most frequent, although if others of greater severity appear, it is important to see a specialist as soon as possible ; we talk about symptoms such as (these are just some of them):

  • Changes in vision
  • Confusion
  • Breathing or swallowing difficulties
  • Darker colored urine (e.g., brown)
  • In women: breast milk production (when not breastfeeding)
  • Nipple or breast augmentation
  • Mood changes (e.g., depressive and/or anxious symptoms)
  • Behavioral changes
  • Chest pain
  • Irregular or rapid heartbeat
  • Fever
  • Increased thirst
  • Seizures
  • Etc.

Other serious effects

On the other hand, mention especially three serious side effects that mesoridazine can cause: akathisia, tardive dyskinesia and neuroleptic malignant syndrome (NMS). These consist of:

1. Akathisia

Akathisia, one of the possible side effects of mesoridazine consists of the inability to keep still and a feeling of uneasiness .

2. Tardive dyskinesia

Tardive dyskinesia is a very typical side effect of antipsychotics. It is a movement disorder, which encompasses a range of symptoms that mainly involve involuntary movements.

3. Neuroleptic Malignant Syndrome (NMS)

Finally, Neuroleptic Malignant Syndrome includes symptoms such as rigidity, fever, dyspnea and arrhythmias . It is a very serious but rare syndrome, which can cause death, and lasts between 5 and 15 days if not killed.

MNS can be caused by multiple antipsychotics, not just mesoridazine.

Bibliographic references:

  • Stahl, S.M. (2002). Essential Psychopharmacology. Neuroscientific bases and clinical applications. Barcelona: Ariel.
  • Vogel, M., Leon, F., Torres, R. and Crossley, N.A. (2017). First and second generation antipsychotics in schizophrenia: efficacy, effectiveness and effect of the dose used. ARS MEDICA, Journal of Medical Sciences, 42(1): 41-48.