Drug cartridge for delivering a drug depot comprising a bulking agent and/or cover

A drug cartridge is provided for delivering a drug pellet to a site beneath the skin of a patient, the drug cartridge comprising: two or more chambers, each chamber holding a drug pellet and having a proximal end and a distal end, the proximal end of the chamber having an opening to receive the drug pellet and a plunger, the distal end of the chamber having an opening for receiving the plunger and passage of the drug pellet, a bulking agent disposed within at least a portion of each chamber, wherein movement of the plunger to an extended position moves the drug pellet within the chamber of the cartridge out the distal end of the chamber and out of the drug cartridge. In some embodiments, instead or with the bulking agent pierceable superior and inferior covers are used to contain the drug pellets.