NCIt definition : An aerosol inhalation formulation containing gemcitabine (GCB), a broad-spectrum antimetabolite
and deoxycytidine analogue, with potential antineoplastic activity. Upon inhalation
via a nebulizer, GCB is converted intracellularly by deoxycytidine kinase to its active
metabolites difluorodeoxycytidine di- and triphosphate (dFdCDP, dFdCTP). dFdCDP inhibits
ribonucleotide reductase (RNR), thereby decreasing the deoxynucleotide pool available
for DNA synthesis; dFdCTP competes with deoxycytidine triphosphate (dCTP) and is incorporated
into DNA, resulting in DNA strand termination and the induction of apoptosis of lung
tumor cells. GCB administration directly into the lungs via aerosol yields higher
concentrations of GCB locally than can be achieved by systemic GCB administration,
potentially reducing systemic toxicity.;