Objective Blonanserin (BNS) possesses anti-serotonin 5-HT 2A activity in addition to anti-dopamine D 2 activity, which is characteristic of second-generation antipsychotics, little information is available on its pharmacologic profile in vivo. We investigated the BNS daily dose, plasma concentration, plasma anti-D 2 activity, and plasma anti-5-HT 2A activity in schizophrenia in a total of 14 subjects. Methods Blood samples were taken 14 days after the BNS dose was fixed, and the plasma concentration was measured by means of highperformance liquid chromatographic (HPLC) method. In addition, the plasma anti-D 2 activity and anti-5-HT 2A activity were measured by means of radioreceptor assays in which [ 3 H]-spiperone and [ 3 H]-ketanserin were used.
Results
The results revealed a statistically significant correlation between the daily dose and the plasma concentration ( p ΒΌ 0.04). Statistically significant correlations were also observed between the plasma concentration and the anti-D 2 activity and between the plasma concentration and the anti-5-HT 2A activity ( p ΒΌ 0.003 and 0.04). Conclusions It is therefore believed that both the anti-D 2 activity in plasma and the anti-5-HT 2A activity in plasma are regulated almost solely by the unchanged principal. Moreover, the mean plasma serotonin/dopamine (S/D) ratio was 0.9 and BNS exhibited both anti-D 2 activity and also anti-5-HT 2A activity in vivo, as well, so it was clear that the in vitro pharmacological profile was retained in vivo.