948 Phenobarbital (PB) influence on ifosfamide (IF) pharmacokinetics (PK) in sarcoma patients

Ten patients (pts) (3 males and 7 females) were treated with high-dose IF for osteosarcoma (2 pts) and soft tissue sarcoma (8 pts). At each course, the pts received 4 g/m 2 IF as a one hour iv infusion every day for 3 days. The courses were repeated every 4 weeks. PB treatment was only started at the second course and was continued for the following courses at a dose of 60 mg per day the 3 days of IF iv infusion. The PK were performed the 1st studies and 3rd day of each course (35 pK analyzed). The results of the PK analysis showed a statistical difference of the pK parameters between the 1st and the 3rd day of each course without or with PB. The mean values of AUC Cl and tl/2 for the 1st and 3rd day of the course without PB were respectively 1.07 and 0.51 mg/ml × h ( P 2 ( P P For the following courses with PB, no difference for the PK parameter values was found among all the 1st days and among all the 3rd days of treatment. The conclusion of this study is that PB concomitant administration does not influence IF pharmacokinetics.