Clozapine

Introduction

Clozapine is an atypical antipsychotic drug, used mainly in the treatment of schizophrenia. It is also particular effective in treating patients who have not responded to other medications. It works mainly by blocking certain chemical messengers in the brain.

Uses

Clozapine is mainly used to treat severe symptoms of schizophrenia that have not responded to other medications. It has also been shown to be effective in the treatment of certain other psychiatric disorders such as bipolar disorder, major depressive disorder, and schizoaffective disorder.

Brand Name	Clozapine
Type
Weight
Generic	Clozapine
Manufacturer
Available in	English বাংলা

Mechanism of Action

Clozapine works mainly by blocking the effects of several chemical messengers in the brain, including dopamine and serotonin. By blocking these messengers, clozapine reduces symptoms of schizophrenia such as delusions, hallucinations, and disorganized thinking.

How Long Does it Take to Work?

Clozapine usually begins to take effect within a week or two of taking the medication. However, it may take several weeks or even months before the full effects of the medication are felt.

Absorption

Clozapine is rapidly and completely absorbed when taken orally. It is absorbed faster in the small intestine than in the stomach.

Route of Elimination

Clozapine is eliminated mainly through the kidneys. A small amount is also excreted in the feces.

Dosage

Schizophrenia: Adult over 16 years, 12.5 mg once or twice (elderly 12.5 mg once) on first day then 25-50 mg (elderly 25-37.5 mg) on second day then increased gradually (if well tolerated) in steps of 25-50 mg daily (elderly max. increment 25 mg daily) over 14-21 days up to 300 mg daily in divided doses (larger dose at night, up to 200 mg daily may be taken as a single dose at bedtime); if necessary may be further increased in steps of 50-100 mg once (preferably) or twice weekly; usual dose 200-450 mg daily (max. 900 mg daily)

Psychosis in Parkinson's disease: Adult over 16 years, 12.5 mg at bedtime then increased according to response in steps of 12.5 mg up to twice weekly; usual dose range 25-37.5 mg at bedtime, usual maximum 50 mg daily; exceptionally, dose may be increased further in steps of 12.5 mg weekly to maximum 100 mg daily in 1-2 divided doses.

Clozapine is available in tablet form in doses of 12.5, 25, 37.5, 50, 75, 100, and 150 mg. The typical starting dose is 12.5 mg once a day, increasing to 25 mg once a day, and then increasing further as needed.

Administration

Clozapine should be taken with food, preferably at night, to reduce the risk of side effects. It should not be chewed or crushed, as this may increase the risk of side effects.

Side Effects

The most common side effects of clozapine include drowsiness, dizziness, weight gain, constipation, dry mouth, blurred vision, and tremor. Other serious side effects, such as an increased risk of developing diabetes or seizures, are also possible.

Toxicity

Clozapine is toxic if taken in overdoses. Symptoms of an overdose may include slurred speech, confusion, rapid heartbeat, agitation, and seizures.

Precautions

Clozapine should not be taken by people who have an allergy to it, or who have certain medical conditions, such as heart problems, liver or kidney problems, or a history of seizures.

Interactions

Clozapine may interact with alcohol, certain medications, or certain herbs or supplements. People should speak to their doctor if they are taking any other medications, including over-the-counter medications, herbs, or supplements.

Disease Interaction

Clozapine may worsen certain medical conditions, such as diabetes, heart or blood pressure problems, or seizures. People should tell their doctor if they have any pre-existing medical conditions before taking clozapine.

Drug Interaction

Clozapine may interact with a number of drugs, including certain antidepressants, anticonvulsants, and antipsychotic medications. People should tell their doctor about all medications they are taking, including over-the-counter medications, herbs, or supplements, before taking clozapine.

Food Interactions

Clozapine may interact with certain foods, such as grapefruit juice or high-fat meals. People should talk to their doctor about food interactions before taking clozapine.

Pregnancy Use

Clozapine should not be taken by pregnant women, as it may cause harm to the developing baby. Women who are breastfeeding should also avoid clozapine.

Lactation Use

Clozapine should not be taken by women who are breastfeeding, as it may pass into their breast milk.

Acute Overdose

An overdose of clozapine can be fatal. Symptoms of an overdose include drowsiness, confusion, rapid heartbeat, agitation, and seizures. If an overdose is suspected, medical attention should be sought immediately.

Contraindication

Clozapine should not be taken if a person has an allergy to it, or have certain medical conditions, such as heart problems, liver or kidney problems, or a history of seizures.

Use Direction

Clozapine should be taken as directed by the doctor. It should be taken with food, preferably at night, to reduce the risk of side effects. It should not be chewed or crushed.

Storage Condition

Clozapine should be stored in a cool, dry place, away from direct light or heat. It should be kept out of the reach of children and pets.

Volume of Distribution

Clozapine has an apparent volume of distribution of about 0.8L/kg.

Half Life

Clozapine has a half-life of about 20 hours, although this may vary from person to person.

Clearance

Clozapine has an oral clearance of about 14ml/min/kg.

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Some Frequently Asked Questions About Clozapine