Olanzapine

This is a thienbenzodiazepine similar in structure to clozapine. Olanzapine has less affinity for D2-receptors than do conventional antipsychotics but more than clozapine. It binds strongly to several 5HT receptor subtypes and to histaminergic, muscurinic and alpha1- and alpha2- adrenergic.

Olanzapine is as effective as haloperidol at relieving symptoms of schizophrenia, but is less likely to cause extrapyrimidal symptoms. Olanzapine appears to be more effective than haloperidol in the treatment of negative symptoms of schizophrenia.

Drugs and Therapeutics bulletin in 1997 stated that. "..on present evidence, olanzapine is well worth trying in patients who have responded to conventional antipsychotics but who develop extrapyrimidal symptoms. Other possible advantages such as effects on negative symptoms need confirmation (1)."

Olanzapine has been given approval for the use in the treatment of moderate to severe manic episode (2). However olanzapine is not approved for the treatment of dementia-related psychosis and/or behavioural disturbances and is not recommended for use in this particular group of patients (3) - this guidance relates to safety information from clinical trials involving elderly patients treated with olanzapine where the patient group treated with olanzapine showed a two-fold increase in mortality compared with placebo and a three-fold increase in cerebrovascular events compared with placebo (3).

Please consult the summary of product characteristics before prescribing this drug.

Reference:

1. Drugs and Therapeutics Bulletin (1997), 35(7),81-3.
2. Eli Lilly and Company Limited (June 2002). Zyprexa (olanzapine) New indication for the treatment of moderate to severe manic episode.
3. Eli Lilly and Company Limited (March 2nd 2004). Important Safety Information on olanzapine and risk of mortality and stroke in elderly patients with dementia-related psychosis and/or behavioural disturbances.