Measurement of haloperidol reductase activity in red blood cells and reduced haloperidol/ haloperidol ratios in plasma in oriental psychiatric patients

Shibaski Morikazu, Toshiyuki Someya, Tadafumi Kato, Toshifumi Noguchi, Nobuya Ishida and Saburo Takahashi: Measurement of Haloperidol Reductase Activity in Red Blood Cells and Reduced Haloperidol/ Haloperidol Ratios in Plasma in Oriental Psychiatric Patients. Prog. Neuro-Psychopharmacol. & Biol. Psychiat. 1990, 14 : 941–947. 1. 1. The authors established a method for measuring haloperidol (HAL) reductase activity in human red blood cells. 2. 2. Characteristics of the HAL reductase in red blood cells were examined. This enzyme reaction was NADPH dependent, and the optimum pH was at 8.2–8.9. Vmax and Km were calculated as 25–150 pmol/hr/10 6RBC and 160–2600 μM respectively. 3. 3. HAL reductase activities in red blood cells from 14 patients treated with HAL were in a range of 9.7–20.8 pmol/hr/10 6 RBC. So far we did not find any significant correlation between HAL reductase activities and reduced HAL/HAL ratios in plasma.