Haloperidol reductase activity in red blood cells from oriental patients on haloperidol

1. We measured haloperidol reductase activity in red blood cells in 87 samples collected from 50 Japanese psychiatric patients on HAL. HAL reductase activities in the patients were in a range of 7.9-26.1 pmol/hr/10(6) RBC (mean = 13.4, S.D. = 3.4). Interindividual variability was as large as 25.4% (CVs), while intraindividual CVs were small (8.9%). 2. Distribution of HAL reductase activities was normal but their values were slightly lower in the patients than those in the normal controls, though the difference between these two groups was not significant. 3. No significant correlations were found between HAL reductase activity in RBC vs dose of HAL per body weight, or plasma and RBC RHAL/HAL ratio.