A SIMPLE ISOCRATIC ION-PAIR HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF 1-BETA-D-ARABINOFURANOSYLCYTOSINE 5'-TRIPHOSPHATE FOR INTRACELLULAR DRUG-MONITORING AND INVITRO INCUBATION ASSAYS

A sensitive isocratic ion-pair HPLC method using a reversed-phase C18 column and phosphate buffer at pH 6 for the determination of the cytotoxic intracellular anabolite 1-beta-D-arabinofuranosylcytosine-triphosphate (Ara-CTP) of the antineoplastic drug cytarabine in leukaemic cells in vivo is described. Simultaneous determination of the physiological nucleotide deoxycytidine-triphosphate is possible. The recovery from cells is > 90%, the limit of detection is 25 ng ml-1 (51 nM l-1) and about 10 pM mg-1 cell protein. Extraction procedure and pitfalls are discussed. The method enables intracellular drug monitoring of Ara-CTP with standard HPLC equipment.