Aspartic acid ester prodrug of cytarabine

Cytarabine (Ara-C, Cytosine Arabinoside) is a well-known antimetabolite used primarily in the treatment of leukemia and lymphomas. It has poor oral bioavailability (approx. 20%) and is given by continuous IV infusion. The poor bioavailability is due to its low permeability across the intestinal membrane and extensive deamination by cytidine deaminase. Thus any strategies that increase permeability of Ara-C via intestinal membrane can result in increased bioavailability mainly through oral route of administration. In order to achieve this goal, amino acid ester prodrug of Cytarabine was synthesized by using Boc protected aspartic acid and it was purified by column chromatography. The primary objective of study was to evaluate whether the Aspartic acid ester prodrug of Ara-C would permeate through the intestinal membrane effectively as compared to the parent drug, Ara-C. The stability of prodrug in various physiological pH such as 7.4, 5, 2 and enzymatic hydrolysis in Caco-2 cell homogenate was evaluated. From the study, it was found that the rate of hydrolysis of prodrug was much faster in Caco-2 cell homogenate than in physiological pH solutions which confirm the role of enzymes in conversion of prodrug in to the drug and stability of prodrug in the physiological pH. The cytotoxicity was tested by XTT assay using HeLa and Caco-2 cell lines. Intestinal epithelial membrane permeability of prodrug was also analyzed and it was found that the prodrug was more permeable than the parent drug across the Caco-2 cell monolayer.