Zyprexa (olanzapine) is an oral medication used primarily to treat schizophrenia and bipolar disorder. It was most recently approved to also treat resistant depressive disorder along with fluoxetine (Prozac). It is part of a class of medications called atypical antipsychotics.
Atypical antipsychotics were developed to be different from the older antipsychotic drugs that tended to cause extrapryimidal side effects (involuntary muscle contractions, tremor, slurred speech, restlessness, anxiety, distress, paranoia, and slowed thought) and increased the levels of a hormone called prolactin, which caused sexual and fertility side effects.
The mechanism of action of atypical antipsychotics has not been fully elucidated, but it is believed that all of them have some action on the dopamine receptors in the brain. Atypical antipsychotics have become the first line therapy for schizophrenia and bipolar disorder, and have generally replaced the old typical antipsychotics due to having a higher response rate, lower risk of suicide, and a better quality of life and functionality for patients. However, atypical antipsychotics still carry the risk of serious side effects, including the development of a movement disorder called tardive dyskinesia, neuroleptic malignant syndrome, and increased risks of developing stroke, blood clots, and diabetes.