Methods, devices, and medicaments that include gemicitabine are provided for use in the treatment of the prostate disease by locally administering gemicitabine into the bladder of a patient to achieve a sustained concentration of the drug in urine in the bladder sufficient to produce a therapeutic concentration of the drug in the prostate. Gemicitabine may be delivered into the bladder from an intravesical drug delivery device inserted into the bladder, wherein the device continuously releases the drug into the urine in the bladder over an extended period of hours or days.