Olanzapine

Olanzapine (Zyprexa) is a high affinity for 5-HT2 serotonin and D2 dopamine receptor antagonist. It has a higher affinity for 5-HT2 serotonin receptors than D2 dopamine receptors. Like most atypical antipsychotics, compared to the older typical ones, olanzapine has a lower affinity for histamine, cholinergic muscarinic and alpha adrenergic receptors. Olanzapine also exhibits weak affinity for GABAA, BZD receptor site which may contribute slightly to its sedating properties. Antagonizing H1 histamine receptors causes sedation and may cause weight gain, although antagonistic actions at 5-HT2C receptors have also been implicated in weight gain.