The present disclosure relates, according to some embodiments, to compositions, methods, devices, and systems for delivering a composition (e.g., a fluid composition) to a subject. For example, the present disclosure relates to non-gassing, direct current (DC), electro-osmotic pumps in some embodiments. A pump may comprise an anode (e.g., a porous silver/silver oxide anode), a cathode (e.g., a porous silver/silver oxide cathode), and a membrane (e.g., a porous ceramic membrane) positioned at least partially between the anode and the cathode in some embodiments. A pump system may comprise an electro-osmotic pump, a reservoir comprising a pump fluid chamber in fluid communication with the electro-osmotic pump and a delivery fluid chamber in fluid communication with the electro-osmotic pump; a controller assembly in electrical communication with the anode and the cathode; and a cannula and/or a needle in fluid communication with the delivery fluid chamber. A pump fluid may comprise water and/or a delivery fluid may comprise a drug, in some embodiments.