A review of olanzapine as an antiemetic in chemotherapy-induced nausea and vomiting and in palliative care patients.

Olanzapine is an atypical antipsychotic agent that blocks multiple neuronal receptors involved in the nausea and vomiting pathways. It has therefore been studied for the prevention and treatment of chemotherapy-induced emesis and in patients in palliative care presenting nausea and vomiting refractory to standard antiemetics. Some studies have shown that olanzapine was not inferior to aprepitant in the prophylaxis of highly and moderately emetogenic chemotherapy and that it increased the rate of complete response when added to a combination of a 5-HT3 antagonist, aprepitant and dexamethasone. These studies present so many shortcomings, however, that they do not permit us to draw any firm conclusions. Oral olanzapine showed superior antiemetic efficacy to metoclopramide as rescue treatment to control breakthrough emesis induced by chemotherapy. However, an oral formulation is not appropriate because in patients with vomiting or severe nausea the mere ingestion of an oral drug could induce emesis. Finally, in palliative care olanzapine could control or reduce the intensity of nausea and vomiting refractory to standard antiemetics.