The plasma concentration profile of
bleomycin in the distribution phase of patients younger than 65 years is needed to determine the suitable time interval for efficient application of electric pulses during electrochemotherapy. Additionally,
bleomycin concentrations in the treated
tumors for effective
tumor response are not known. In this study, the pharmacokinetic profile of
bleomycin in the distribution phase in 12 patients younger than 65 years was determined. In 17 patients, the intratumoral
bleomycin concentration was determined before the application of electric pulses. In younger patients, the pharmacokinetics of intravenously injected
bleomycin demonstrated a faster plasma clearance rate than that in patients older than 65 years. This outcome might indicate that the lowering of the standard
bleomycin dose of 15,000 IU/m2 with intravenous
bleomycin injection for electrochemotherapy is not recommended in younger patients. Based on the plasma concentration data gathered, a time interval for electrochemotherapy of 5-15 min after
bleomycin injection was determined. The median
bleomycin concentration in
tumors 8 min after
bleomycin injection, at the time of electroporation, was 170 ng/g. Based on collected data, the reduction of the
bleomycin dose is not recommended in younger patients; however, a shortened time interval for application of electric pulses in electrochemotherapy to 5-15 min after intravenous
bleomycin injection should be considered.