The relationship between the daily dose, the plasma concentration of blonanserin, and its plasma anti-dopamine D-2 and anti-serotonin 5-HT2A activity

Objective Blonanserin (BNS) possesses anti-serotonin 5-HT2A 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-HT2A 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 high-performance liquid chromatographic (HPLC) method. In addition, the plasma anti-D-2 activity and anti-5-HT2A activity were measured by means of radioreceptor assays in which [H-3]-spiperone and [H-3]-ketanserin were used. Results The results revealed a statistically significant correlation between the daily dose and the plasma concentration (p = 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-HT2A activity (p = 0.003 and 0.04). Conclusions It is therefore believed that both the anti-D-2 activity in plasma and the anti-5-HT2A 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-HT2A activity in vivo, as well, so it was clear that the in vitro pharmacological profile was retained in vivo. Copyright (C) 2010 John Wiley & Sons, Ltd.