What are a prefilled syringe’s key components?
A prefilled glass syringe is a small system consisting of a barrel, a plunger, a plunger rod, or a piston. The syringe may be supplied with a barrel cone and closure type that supports the attachment of a suitable needle later when the injection is administered. Alternatively, the syringe may be manufactured with a pre-attached needle and a protective needle shield (see picture). This is often the case for drugs that are administered as subcutaneous (SC) injections, where patient age, weight, and other demographic factors are less important.
In contrast with disposable syringes, fluid is not drawn up manually into prefilled glass syringe barrels when the injection is administered. Instead, the pharmaceutical manufacturer fills the syringe barrels with the drug during the sterile manufacturing process. The plunger and plunger rod are also inserted into the barrel during this manufacturing process. When the injection is given, the plunger and plunger rod work together to exert downward pressure on the fluid, forcing it through the needle’s sharp, hollow tube and allowing it to enter the body.