An electrical feedthrough assembly, which is configured to be mounted on a housing of a leadless biostimulator, comprises an electrode body including a cup having an electrode wall extending distally from an electrode base around an electrode cavity, an electrode tip mounted on a distal end of the electrode body, and a filler in the electrode cavity between the electrode base and the electrode tip, wherein the filler includes a therapeutic agent. The electrode tip is configured to be placed in contact with target tissue to which a pacing impulse is to be transmitted by the leadless biostimulator. A pin extends proximally from the electrode base, wherein the pin is configured to be into contact with an electrical connector of an electronics assembly within the housing of the leadless biostimulator.