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Clozapine: operation, precautions and adverse effects

Clozapine: operation, precautions and adverse effects

March 14, 2023

One of the main drawbacks of traditional antipsychotic medication is the amount of time it takes to act, as well as its possible adverse effects. However, in the 1950s it was synthesized for the first time clozapine, an atypical antipsychotic that is well known today .

Throughout this article we will discuss its effectiveness, its way of acting in the body, as well as its advantages and disadvantages, and the precautions that should be taken by those who use this drug.

  • Related article: "Atypical antipsychotics: characteristics and main uses"

What is clozapine?

Clozapine is a benzodiazepine which is included in the group of atypical antipsychotics. The atypical denomination is attributed to him by his differences with the rest of ordinary antipsychotics.


These differences lie in the fact that the former provoke far fewer extrapyramidal symptoms and also show great effectiveness in treating both the positive and negative symptoms of schizophrenia.

This drug achieved fame quickly because of its advantages over other antipsychotics, including its greater effectiveness. However, despite these advantages, Clozapine has a lot of unwanted side effects that affect other functions of the organism.

Within its particular history, clozapine was withdrawn from the market in the 70s when it was related to a series of cases of death by agranulocytosis in people taking this drug. However, approximately ten years after its withdrawal and due to its high efficacy, clozapine was reintroduced on the market with the obligation for the manufacturer to carry out blood tests in order to detect any dangerous side effects.


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In what disorders is it used?

Due to its toxicity, the administration of clozapine is restricted only to schizophrenias resistant to other antipsychotics, as well as to more severe schizophrenias with significant extrapyramidal symptoms or with suicide attempts and self-harm.

Further, accompanied by psychological intervention and training in psychosocial skills , clozapine has been established as the reference drug in the treatment of childhood schizophrenia.

Although its use is not recommended in any other case other than the treatment of schizophrenia , very exceptional occasions are administered in patients who present psychotic symptoms and certain neurological conditions in which psychotic symptoms may also arise.


The form of administration

Clozapine is a medicine that is administered orally in both tablet and oral suspension. Normally the recommended dose is one or two doses a day, to be able to be always at the same time. However, It is essential that the patient follow the instructions of his doctor to the letter and ask for advice in case of any doubt that may arise.

Usually, the treatment starts progressively; starting with low doses until the patient's body admits the medication. Likewise, the patient must have a weekly control during the first four months after the start of treatment, after this period the analytics will be performed once a month.

When the medicine reaches its maximum therapeutic effect it is necessary to make a medication adjustment so that it is not exceeded in its effects and thus avoid possible unwanted consequences.

Finally, after cessation of therapy, it is recommended to withdraw clozapine progressively for one or two weeks. When the withdrawal of the drug should be done immediately, due to some pathology such as leukopenia or decrease in the number of leukocytes in blood, it is essential to closely monitor the patient's symptoms.

What precautions should the patient take?

First of all it is necessary to make sure that the patient is not allergic to clozapine or to any of the compounds it contains. Also, the patient should inform his doctor if he takes any medication, vitamin supplement or herbal compounds, especially in the case of St. John's wort.

On the other hand, there are a number of special conditions that must be taken into account before the administration of clozapine. These conditions are related to a series of Conditions and syndromes that may be incompatible with this drug .

1. Heart failure

Patients with severe cardiovascular conditions should be especially careful if they consume clozapine, since they can cause hypotension caused by hemodynamic changes.

2. Diabetes

It is possible that clozapine alter blood glucose levels , so that diabetics should have a particular control.

3. Chronic respiratory diseases

All patients who are clozapine users who suffer from asthma or obstructive pulmonary disease should know that this medication may favor the appearance of depressant effects on respiratory function.

4. Epilepsy

Neuropathic medications can reduce the seizure threshold, causing a risk of seizures .

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5. Depression

Clozapine is characterized by exerting a depressant effect on the central nervous system, which is why People with depression should pay special attention to their symptoms .

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6. Hepatic insufficiency

Most of clozapine is metabolized by the liver. Therefore, it is advisable adjust the doses to the level of liver function .

8. Parkinsonism

Although the incidence of the effects of clozapine on extrapyramidal effects is much lower than with other types of antipsychotics, it can potentiate them, thus aggravating the disease.

6. Constipation

The anticholinergic action of clozapine can cause complications in constipation, causing intestinal obstruction and paralytic ileus.

Other risks

In addition to potentiating alterations of health that are already present before taking the drug. For example, clozapine can increase photosensitivity , so it is advisable to avoid continuous exposure to the sun.

Further, you run the risk of suffering the neuroleptic malignant syndrome , a life-threatening condition related to the use of antipsychotics. If the person notices symptoms such as fever, tachycardia or altered consciousness, without a justifiable cause, the pharmacological therapy should be suspended.

Finally, it is totally inadvisable in handling or driving heavy or dangerous machinery due to the possible appearance of drowsiness or dizziness. In the same way, those people who are usually exposed to high temperatures usually, should also pay special attention, since clozapine can cause a heat stroke or hypothermia, due to the elimination of hypothalamic regulation.

  • Related article: "Neuroleptic malignant syndrome: symptoms, causes and treatment"

What side effects can appear?

Among the unwanted side effects associated with clozapine we can find those that appear frequently, the rare and those that appear rarely.

Frequent side effects

  • Dizziness .
  • Sensation of sleep.
  • Tachycardia.
  • Hypotension
  • Constipation.
  • Weight gain .
  • Gastrointestinal disorders.
  • Urinary incontinence

Uncommon effects

  • Disorientation.
  • Insomnia .
  • Feeling tired.
  • Tremors
  • Headache .
  • Convulsions
  • Nightmares .
  • Hypertension and hypotension.
  • Leukopenia
  • Hyperhidrosis .
  • Myoclonic tics

Rare side effects

  • Myocardial infarction.
  • Impotence.
  • Arrhythmias .
  • Granulocytopenia
  • Thrombocytopenia
  • Increase in blood glucose levels.
  • Pulmonary embolisms .
  • Glaucoma.

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