Drug delivery devices (200) and methods of their use are provided. In one embodiment, a drug delivery device (200) for use with a urinary catheter (100) includes a drug reservoir configured to be disposed outside of a patient's body, and a flexible elongate body (220) attached to the drug reservoir (230) and configured to traverse the patient's urethra to reach the bladder. The drug reservoir (230) includes a drug chamber (234) containing a drug therein, a fluid chamber (236) containing a fluid therein, and an osmotic barrier (238) separating the drug chamber (234) and the fluid chamber (236). The body includes a drug delivery lumen (222) extending therethrough and in fluid communication with the drug chamber (234).