Using prefilled syringes. (A) The prefilled cartridge is inserted into the holder/injection device. (B) The plunger section is positioned over the cartridge and screwed on to tighten it. This holds the cartridge in place. The cartridge may need to be pushed firmly into place (to break its seal) before injection. The injection is then given as with any syringe. This is not a safety syringe; therefore, the needle must be protected after use (see Fig. 64-4B).