Gemcitabine kills cells undergoing DNA synthesis and blocks the progression of cells through the G1/S-phase boundary. It is metabolized by nucleoside kinases to diphosphate (dFdCDP) and triphosphate (dFdCTP) nucleosides. Gemcitabine diphosphate inhibits ribonucleotide reductase, an enzyme responsible for catalyzing the reactions that generate deoxynucleoside triphosphates for DNA synthesis, resulting in reductions in deoxynucleotide concentrations, including dCTP. Gemcitabine triphosphate competes with dCTP for incorporation into DNA. The reduction in the intracellular concentration of dCTP by the action of the diphosphate enhances the incorporation of gemcitabine triphosphate into DNA (self-potentiation). After the gemcitabine nucleotide is incorporated into DNA, only one additional nucleotide is added to the growing DNA strands, which eventually results in the initiation of apoptotic cell death.
Gemcitabine hydrochloride is approved to be used alone or with other drugs to treat:
The caner that cannot be treated with or did not respond to chemotherapy that included an anthracycline drug. It is used with paclitaxel as first-line therapy for cancer that has metastasized (spread to other parts of the body).
The n that is locally advanced or metastatic and cannot be removed by surgery. It is used with cisplatin.
This cancer at an advanced stage has relapsed at least 6 months after treatment with platinum chemotherapy. It is used with carboplatin.
It is used alone in patients whose disease is locally advanced or metastatic and who have been treated with fluorouracil.
Gemcitabine hydrochloride is also being studied in the treatment of other types of cancer.