A device for delivering buffer solution into a buffer cartridge comprises aneedle assembly and a pusher. The septaof a buffer cartridge and an anesthetic cartridge are advanced onto a transferneedle, and the pusher advances a plunger into thebuffer cartridge to deliver buffer through the transfer needle into theanesthetic cartridge. A separate exhaust needle allows excessanesthetic from the anesthetic cartridge to be exhausted. A compression memberis usually provided to maintain a force againstthe plunger on the buffer cartridge to pressurize and stabilize the contentsduring sterilization and/or storage.
