PHARMACOKINETICS OF IFOSFAMIDE ADMINISTERED ACCORDING TO 3 DIFFERENT SCHEDULES IN METASTATIC SOFT-TISSUE AND BONE SARCOMAS

Ifosfamide is a leading drug in soft tissue sarcoma therapy. Recently high dose therapy (>9 g/m(2)) has been introduced in different schemes to obtain a higher response rate. All these higher doses can be admin istered following two different schedules: continuous infusion 24 hour s a day for 4-5 days or bolus administration for 5 consecutive days. I n this study we compare the differences in the pharmacokinetic profile between the two schedules. In both schemes we saw a very important au toinduction phenomenon, with a corresponding half-life decrease and to tal body clearance increase during the days of therapy, The clearances were not directly correlated with the administered dose. We can concl ude that ifosfamide continuous infusion therapy is equivalent to fract ionated administration, at least from a pharmacokinetic point of view. Short-term infusion is subjectively better tolerated and is therefore preferred.