Prodrug This invention relates to a prodrug of the monophosphate nucleotide of the well-known oncology drug gemcitabine. Specifically, it relates to gemcitabine-[phenyl-benzoxy-L- alaninyl)]-phosphate when present as a single phosphate diastereoisomer and, in particular, it relates to the (S)-phosphate diastereoisomerwhich offers a remarkable and unexpected increase in solubility relative to the (R)-diastereoisomer. The (S)-phosphate epimer is also preferentially taken up into cyclodextrin solutions over the (R)- diastereoisomer.
