Background: Olanzapine is an atypical antipsychotic drug with high clinical efficacy, but which can cause severe
weight gain and metabolic disorders in treated patients. Blockade of the histamine 1 (H1) receptors is believed to
play a crucial role in olanzapine induced weight gain, whereas the therapeutic effects of this drug are mainly
attributed to its favourable serotoninergic 2A and dopamine 2 (5HT2A/D2) receptor binding affinity ratios.
Results: We have synthesized novel olanzapine analogues 8a and 8b together with the already known derivative
8c and we have examined their respective in vitro affinities for the 5HT2A, D2, and H1 receptors.
Conclusions: We suggest that thienobenzodiazepines 8b and 8c with lower binding affinity for the H1 receptors,
but similar 5HT2A/D2 receptor binding affinity ratios to those of olanzapine. These compounds may offer a better
pharmacological profile than olanzapine for treating patients with schizophrenia.

• Novel olanzapine analogues presenting a reduced H1 receptor affinity and retained 5HT2A/D2 binding affinity ratio