Microsomal enzymes in patients with acute leukemia as determined by plasma half-life of antipyrine.

The metabolism of antipyrine was studied in five patients with acute leukemia, before and after treatment and in relapse, to ascertain the effects of treatment on hepatic microsomal enzyme activity. The mean antipyrine half-life was significantly longer in patients after treatment (15.0 +/- 3.7 h) than in patients before treatment (8.8 +/- 0.7 h) (P less than 0.02). Furthermore, the mean antipyrine half-life in patients after treatment was also significantly longer than in patients in relapse (9.2 +/- 2.7 h) (P less than 0.05). Similarly, the mean metabolic clearance rate of antipyrine was significantly lower in patients after treatment (26.9 +/- 2.2 ml/h/kg) than in patients before treatment (46.7 +/- 13.1 ml/h/kg) (P less than 0.02). The mean apparent volume of distribution was not significantly different during the course of acute leukemia. The mean transaminase activity in patients after treatment was significantly higher than that in patients before treatment and in relapse. Thus, treatment with antileukemic agents and blood transfusions might alter hepatic microsomal enzyme activity.