Chronopharmacokinetics of doxorubicin in patients with breast cancer

The chronopharmacokinetics of doxorubicin (DOX) has been studied in 18 patients suffering from breast cancer. They received combined chemotherapy including DOX (50 mg/m2 as an iv bolus), given at two different times (09.00 h or 21.00 h). The two randomized courses of the protocol were given to each patient at a four week interval. The total body clearance (CL) of DOX was significantly decreased when the drug was administered at 21.00 h, resulting in a longer elimination half-life and an increase in AUC. The renal clearance of DOX did not differ at the different times of administration, and it appears that the decrease in CL was related to a change in hepatic blood flow. The volume of distribution of the drug was not changed.