Method of terminal steam sterilization

A method for terminal sterilization of a pre-filled plastic cartridge comprising:

• providing
• a cartridge barrel terminating in a neck portion at a distal end of the cartridge barrel constructed and arranged to receive a pierceable diaphragm, and an open or proximal end and
• a slideable plunger situated in the cartridge barrel sealing the proximal end of the cartridge barrel to retain a liquid therein and having a means to engage a plunger rod;
• inserting the slideable plunger into the cartridge barrel and positioning the slideable plunger to leave a volume of at least 2% empty space between the slideable plunger and the proximal end of the cartridge barrel;
• filling the cartridge barrel with the liquid through the distal end of the cartridge barrel allowing for a head space not exceeding 10% by volume;
• hermetically sealing the distal end by a pierceable diaphragm;
• placing the pre-filled plastic cartridge into an autoclave chamber to sterilize the liquid therein, said pre-filled plastic cartridge having a pressure on the outside surfaces of the pre-filled plastic cartridge exerted by a steam atmosphere in the autoclave chamber and an internal pressure of the liquid contained in the pre-filled plastic cartridge;
• and
• autoclaving the pre-filled plastic cartridge at an autoclave pressure less than the pressure of the liquid in the pre-filled plastic cartridge at a rate that will not allow a collapse of the steam atmosphere in the autoclave chamber.

A method for terminal sterilization of a pre-filled glass syringe comprising:

• providing
• a syringe barrel terminating in a nozzle at a distal end of the syringe barrel, and an open or proximal end and
• a slideable plunger situated in the syringe barrel sealing the proximal end of the syringe barrel to retain a liquid therein and having a means to engage a plunger rod;
• inserting the slideable plunger into the syringe barrel and sliding it toward the distal end thereof to leave a volume of at least about 2% empty space between the slidable plunger and the proximal end of the syringe barrel;
• filling the syringe barrel through the nozzle of the syringe barrel with the liquid allowing for a head space not exceeding 10% by volume;
• hermetically sealing the nozzle by a cap;
• placing the pre-filled glass syringe into an autoclave chamber to sterilize the liquid therein, said pre-filled glass syringe having a pressure on outside surfaces of the pre-filled glass syringe exerted by a steam atmosphere in the autoclave chamber and an internal pressure of the liquid contained in the pre-filled glass syringe;
• autoclaving the pre-filled glass syringe at an autoclave pressure less than the pressure inside the pre-filled glass syringe;
• and
• cooling the autoclave chamber with a water cascade or nozzle spray or air draft at a rate that will not allow a collapse of the steam atmosphere in the autoclave chamber.

A method for terminal sterilization of a pre-filled glass cartridge comprising:

• providing
• a cartridge barrel terminating in a neck portion at a distal end of the cartridge barrel constructed and arranged to receive a pierceable diaphragm, and an open or proximal end and
• a slideable plunger situated in the cartridge barrel sealing the proximal end of the cartridge barrel to retain a liquid therein and having a means to engage a plunger rod;
• inserting the slideable plunger into the cartridge barrel and positioning it to leave a volume of at least 2% empty space between the slideable plunger and the proximal end of the cartridge barrel;
• filling the cartridge barrel with the liquid through the distal end of the cartridge barrel allowing for a head space not exceeding 10% by volume;
• hermetically sealing the distal end by a pierceable diaphragm;
• placing the pre-filled glass cartridge into an autoclave chamber to sterilize the liquid therein, said pre-filled glass cartridge having a pressure on outside surfaces of the pre-filled glass cartridge exerted by a steam atmosphere in the autoclave chamber and an internal pressure of the liquid contained in the pre-filled glass cartridge;
• autoclaving the pre-filled glass cartridge at an autoclave pressure that is less than the pressure inside the pre-filled glass cartridge;
• and
• cooling the autoclave chamber with a water cascade or nozzle spray or air draft at a rate that will not allow a collapse of the steam atmosphere in the autoclave chamber.