How does the active diphosphate metabolite of gemcitabine hydrochloride inhibit DNA synthesis?

Gemcitabine hydrochloride’s active diphosphate metabolite, dFdCDP, inhibits ribonucleotide reductase, reducing deoxynucleoside concentrations, particularly dCTP needed for DNA synthesis, which also promotes incorporation of the active triphosphate metabolite, dFdCTP, into DNA.