A method of tuning the release of an active agent from a cartridge disposed in a catheter and related cartridges are disclosed herein. In one embodiment, a method of tuning the release of an active agent from a cartridge disposed in a catheter convector is provided. The method can include establishing a desired release profile for an active agent to be delivered into a catheter, and disposing a cartridge having the active agent associated therewith into a fluid pathway of a catheter connector of the catheter. Thus, when an aqueous solution contacts and passes by the cartridge, the active agent is released from the cartridge at the desired release profile.