For decades, a growing number of antipsychotic agents have been used for treating severe psychotic disorders. Conventional antipsychotic drugs, such as chlorpromazine and haloperidol, have traditionally been used as first line antipsychotic drugs for patients with schizophrenia. The introduction of clozapine in the US in 1990 has resulted in the development of so-called “atypical” or second generation antipsychotics.

Olanzapine is one of those second generation antipsychotics approved for the treatment of schizophrenia and bipolar disorder. Among the newer antipsychotics, its structure and (to a lesser degree) receptor activity most closely resembles clozapine. It was initially approved for clinical use in the European Union in 1996, and has since become one of the most commonly used antipsychotic drugs worldwide.

Clinical use and efficacy

Olanzapine shows more effectiveness in comparison to some other second generation antipsychotic drugs. This drug is useful in acute and maintenance treatment of schizophrenia and related disorders. It exhibits beneficial effects on both positive and negative symptoms, with a favorable side-effect profile and an early onset of the onset of antipsychotic action.

Olanzapine has also been used in the management of bipolar disorder and acute mania (either as monotherapy or in combination with lithium or valproate). Akin to other antipsychotics, it is sometimes used as an adjunct to selective serotonin reuptake inhibitors (SSRIs) in the management of obsessive compulsive disorder and treatment-resistant depression.

This atypical antipsychotic was also researched as a therapeutic strategy for Gilles de la Tourette syndrome, drawing attention to its possible use for comorbid behavioral disorders. It can effectively control tics and improve the patient's quality of life, as well as ability to work.

Although certain studies point to olanzapine as a promising treatment for children with autistic disorder, more research is needed in order to adequately demonstrate its clinical efficacy and tolerability. This drug has also been used to treat psychotic symptoms of Parkinson’s disease, but its use remains controversial as it may aggravate parkinsonian symptoms.

Formulations of the drug

As already mentioned, olanzapine was first introduced as an oral formulation for the treatment of schizophrenia and bipolar disorder. Recent developments have included parenteral formulations in order to improve compliance in the treatment process, as well as to address agitation in patients with schizophrenia and bipolar mania.

Olanzapine pamoate long acting injection (depot) represents newer formulation of the drug, which is licensed for the maintenance treatment of schizophrenia. When administered in the form of pamoate salt, olanzapine has an elimination half-life of approximately 30 days, allowing it to be given once every 2 or 4 weeks (and consequently improving patient adherence).

Controlled release matrix pellets of olanzapine for oral use were also developed, using a blend of sodium alginate and glyceryl palmito-stearate as matrix polymers, sodium lauryl sulphate as pore forming agent, and micro crystalline cellulose as spheronizer enhancer.