Pharmacokinetics of all-trans-retinoic acid in Japanese patients with acute promyelocytic leukemia.

All-trans-retinoic acid (ATRA) was administered at 45 mg/m2 to 4 Japanese patients with acute promyelocytic leukemia (APL). A pharmacokinetic study revealed that the mean peak plasma concentration was 208 ng/ml and was reached at 150 min after ingestion. The mean area under the concentration x time curve (AUC) was 498 ng.h/ml. Two patients showed a good hematological response to ATRA, and they had higher peak plasma concentrations of ATRA and larger AUCs. In one patient, dose escalation of ATRA (90 mg/m2) increased the plasma concentration markedly. In another patient, the plasma concentration decreased markedly in the fasting state. A larger pharmacokinetic study is necessary to examine the influence of food on the absorption of this agent and an optimum administration schedule of ATRA in Japanese APL cases.