Clozapine is an antipsychotic

Antipsychotic

An antipsychotic is a tranquilizing psychiatric medication primarily used to manage psychosis , particularly in schizophrenia and bipolar disorder. A first generation of antipsychotics, known as typical antipsychotics, was discovered in the 1950s...

 medication used in the treatment of schizophrenia

Schizophrenia

Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...

, and is also used off-label in the treatment of bipolar disorder

Bipolar disorder

Bipolar disorder or bipolar affective disorder, historically known as manic–depressive disorder, is a psychiatric diagnosis that describes a category of mood disorders defined by the presence of one or more episodes of abnormally elevated energy levels, cognition, and mood with or without one or...

. Wyatt. R and Chew. R (2005) tells us there are three pharmaceutical companies that market this drug at present: Novartis Pharmaceuticals (manufacturer), Mylan Laboratories and Ivax Pharmaceuticals (market generic clozapine). The first of the atypical antipsychotic

Atypical antipsychotic

The atypical antipsychotics are a group of antipsychotic tranquilizing drugs used to treat psychiatric conditions. Some atypical antipsychotics are FDA approved for use in the treatment of schizophrenia...

s to be developed, it was first introduced in Europe in 1971, but was voluntarily withdrawn by the manufacturer in 1975 after it was shown to cause agranulocytosis

Agranulocytosis

Granulopenia, also known as Agranulosis or Agranulocytosis, is an acute condition involving a severe and dangerous leukopenia , most commonly of neutrophils causing a neutropenia in the circulating blood. It represents a severe lack of one major class of infection-fighting white blood cells...

, a condition involving a dangerous decrease in the number of white blood cells, that led to death in some patients.