Deflexifol (a novel formulation of 5FU): Pharmacokinetics in a phase 1 trial in comparison to 5FU.

2530Background: Simultaneous administration of 5-fluorouracil (5FU) and leucovorin (LV) is generally not feasible as 5FU and LV are chemically incompatible (CaPO4 crystals), so the maximum possible interaction for benefit is not achieved. Deflexifol, an all in one formulation of 5FU/LV with cyclodextrin (HP-β-CD 100mg/ml, 5-FU 15mg/ml & LV 1mg/ml) at pH 7, was developed to overcome this problem. Methods: Limited sampling PK was done with dose 1 and 6 in a standard 3+3 phase I trial of Deflexifol given in two schedules (46-h infusion Q2W or bolus weekly x6) with no intrapatient dose escalation, at doses shown in Table. Sample times were infusion: 0, 2, 46h; bolus: 0, 0.2, 0.4, 1, 24h. 5FU and dihydroFU were measured as per Ackland et al, Anal Biochem 1997. 5FU AUC, clearance (CLR) and t1/2 were estimated for each patient to assess PK variability and adequacy of dosing compared to previous reports. Results: 40 patients were treated (21 infusion, 19 bolus, median age 67, 19 M, 21 F). The MTD(bolus) was 575 m...