Clozapine belongs to a group of medicines called antipsychotics. These medicines work on the balance of chemical substances in the brain which may cause mental illness.
Clozapine is prescribed in particular for people with schizophrenia. It is also known as a second generation antipsychotic (SGA) or atypical antipsychotic. Clozapine rebalances dopamine and serotonin to improve thinking, mood, and behavior.
Schizophrenia is a mental health problem that causes disordered ideas, beliefs and experiences. Someone with schizophrenia may have difficulty distinguishing between what is real and what is imaginary; may be unresponsive or withdrawn; and may have difficulty expressing normal emotions in social situations.
Symptoms of schizophrenia include:
- Hallucinations - imagined voices or images that seem real
- Delusions - beliefs that are not true (e.g., other people are reading your thoughts)
- Disorganized thinking or trouble organizi
- Trouble speaking clearly
- Lack of motivation
Therapeutic Indication:
- For Schizophrenia
- Psychosis in people with Parkinson's disease
Uses:
- Helps reduce the risk of suicidal behavior in people with schizophrenia or similar disorders
- Sometimes used for people who have behavior problems
- Helps you feel calm and relaxed
- Controls your temper
Pharmacology:
Mechanism of Action:
Clozapine has been shown to be an antipsychotic agent that is different from classic antipsychotics. In pharmacological experiments, it does not induce catalepsy or inhibit apomorphine- or amphetamine-induced stereotyped behaviour. It has only weak dopamine receptor-blocking activity at D1, D2, D3 and D5 receptors, but shows high potency for the D4 receptor, in addition to potent anti- alpha-adrenergic, anticholinergic, antihistaminic, and arousal reaction-inhibiting effects. It has also been shown to possess antiserotoninergic properties.
Pharmacodynamic:
Clinically Clozapine produces rapid and marked sedation, and exerts antipsychotic effects in patients with schizophrenia resistant to other antipsychotic agents. In such cases, Clozapine has proven effective in relieving both positive and negative schizophrenic symptoms in short- and long-term trials.
Clozapine is unique in that it produces virtually no major extrapyramidal reactions such as acute dystonia and tardive dyskinesia. Furthermore, parkinsonian-like side effects and akathisia are rare. In contrast to classical antipsychotics, clozapine produces little or no prolactin elevation, thus avoiding adverse effects such as gynaecomastia, amenorrhoea, galactorrhoea, and impotence.
Pharmacokinetics:
Absorption: The absorption of orally administered clozapine is 90% to 95%; neither the rate nor the extent of absorption is influenced by food. Clozapine is subject to moderate first-pass metabolism, resulting in an absolute bioavailability of 50% to 60%.
Distribution: In steady-state conditions, when given twice daily, peak blood levels occur on an average at 2.1 hours (range: 0.4 to 4.2 hours), and the volume of distribution is 1.6 L/kg. Clozapine is approximately 95% bound to plasma proteins.
Metabolism: Clozapine is almost completely metabolised before excretion. Of the main metabolites only the desmethyl metabolite was found to be active. Its pharmacological actions resemble those of clozapine, but are considerably weaker and of short duration.
Excretion: Its elimination is biphasic, with a mean terminal half-life of 12 hours (range: 6 to 26 hours). After single dose of 75 mg the mean terminal half-life was 7.9 hours; it increased to 14.2 hours when steady-state conditions were reached by administering daily doses of 75 mg for at least 7 days. Only trace amounts of unchanged drug are detected in the urine and faeces, approximately 50% of the administered dose being excreted as metabolites in the urine and 30% in the faeces.
Pregnancy and Lactation:
Please consult the doctor before taking this medicine.
Contraindications:
Clozapine is contraindicated in patients with a previous hypersensitivity to clozapine or any other component of this drug, in patients with myeloproliferative disorders, uncontrolled epilepsy, paralytic ileus, or a history of clozapine-induced agranulocytosis or severe granulocytopenia.
Warning & Precaution:
This has been prescribed for the patient's specific condition only.
Side Effects:
The most commonly reported side effects when taking Tamsulosin include: dizziness, headache, abnormal ejaculation, asthenia (weakness), and palpitations.
Storage:
Store protected from light and moisture.