Involvement of CYP4F2 in the Metabolism of a Novel Monophosphate Ester Prodrug of Gemcitabine and Its Interaction Potential In Vitro.

Compound- 3 is an oral monophosphate prodrug of gemcitabine. Previous data showed that Compound- 3 was more potent than gemcitabine and it was orally active in a tumor xenograft model. In the present study, the metabolism of Compound- 3 was investigated in several well-known in vitro matrices. While relatively stable in human and rat plasma, Compound- 3 demonstrated noticeable metabolism in liver and intestinal microsomes in the presence of NADPH and human hepatocytes. Compound- 3 could also be hydrolyzed by alkaline phosphatase, leading to gemcitabine formation. Metabolite identification using accurate mass- and information-based scan techniques revealed that Compound- 3 was subjected to sequential metabolism, forming alcohol, aldehyde and carboxylic acid metabolites, respectively. Results from reaction phenotyping studies indicated that cytochrome P450 4F2 (CYP4F2) was a key CYP isozyme involved in Compound- 3 metabolism. Interaction assays suggested that CYP4F2 activity could be inhibited by Compound- 3 or an antiparasitic prodrug pafuramidine. Because CYP4F2 is a key CYP isozyme involved in the metabolism of eicosanoids and therapeutic drugs, clinical relevance of drug-drug interactions mediated via CYP4F2 inhibition warrants further investigation.