Sequential arabinosylcytosin with or without fludarabine in paracmastic patients with acute myeloid leukemia

The purpose of this study is to assess how fludarabine (Fa) influences arabinosylcytosin's (Ara-C) mode of action. Plasma, cerebrospinal and urine samples were withdrawn from two study groups at specific time points and analyzed by HPLC. Group A was treated with Ara-C only whereas Group B was treated with Fa+Ara-C. The two study groups are all undergoing complete remission (CR). The Ara-C dose for Group A was 3g/m2 x 2, and the AUC(0-4) was 5.131 +/- 0.936. The Ara-C dose for Group B was 2g/m2 x 2, and the AUC(0-4) was 12.245 +/- 3.863. The AUC(0-4) for Group B is more than twice the AUC(0-4) for Group A, and these results indicate that Fa conduces a synergistic increase in the concentration and AUC of Ara-C in plasma and in cerebrospinal fluid. The pharmacokinetics between the different dose treatments was statistically different (P = 0.016). The differences in the ratios of C(Ara-u) to C(Ara-C), and in the Tmax between Groups A and B could indicate whether or not Ara-C combined with Fa. Although Group B demonstrates a higher AUC(0-4) with lower doses of Ara-C (2 g/m2 x 2), the adverse drug reaction (ADR) and bone inhibition were not more pronounced in Group B compared to Group A. These results are based on a limited number of case studies, hence, additional studies are necessary to support and prove this hypothesis.