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Developing a QbD Component
Developing a QbD Component: The Lifecycle of a Syringe Plunger
By Tibor Hlobik
Director, Global Prefillable Syringe Platform
West Pharmaceutical Services, Inc.
Market trends toward home-use and patient self-administration of drugs used to treat chronic conditions (e.g., multiple sclerosis, rheumatoid arthritis and autoimmune diseases) have made prefillable syringe systems an ideal choice for single-dose drugs. Prefilled syringe systems for vaccines, pharmaceuticals and biopharmaceuticals offer convenient, fixed dosing and are adaptable to automated injection devices.
For patients, use of a prefilled syringe system has the potential to minimize microbial contamination and reduce medication dosing errors. The syringe systems offer ease of use and enhanced convenience for those who require frequent dosing, and when combined with an auto-injector system, can provide a more portable drug delivery system.
Most subcutaneous drug product injections use a staked needle 1mL long prefilled syringe format that can retain a fill volume ≤1.0mL. This syringe format is convenient, fits most auto-injectors and is widely used for sensitive pharmaceutical and biotechnology drug applications.
The use of high-quality components in prefillable syringe systems will facilitate efficient manufacturing processes and support a reliable supply of drug products. An elastomeric plunger is a critical element because it serves as the primary seal for container closure integrity, maintains purity of drugs during shelf life, and functions to expel contents of the barrel and deliver drugs to the patient.
Plungers (also named pistons and stoppers) are typically made from butyl rubber and can be coated with a fluoropolymer film, such as FluroTec® film, that can increase lubricity and serve as a barrier between the drug and the elastomer, reducing the potential for exposure to extractables inherent in all materials. The phenomena of chemicals migrating from the elastomers into the drug product is known as leachables, but the reverse process of the drug product adsorbing or absorbing onto the plunger can also occur. Extractables and leachables can be significantly reduced with a barrier film.
For improved manufacturing processes, the pharmaceutical industry has moved toward ready-to-use (RU) plungers for prefillable syringe systems. These components are washed and sterilized prior to delivery to the drug manufacturer with specifications for particulate and endotoxin, thereby reducing the risk of introducing microbiological contamination to the drug product during final packaging. There are several methods for sterilization of plungers, but an increase in extractable breakdown products has been observed under gamma irradiation; therefore, autoclave steam sterilization of these components is a preferred, low-risk choice.
Plungers that fit 1mL long staked needle syringes were originally developed for a manual injection action. As both customer desire for higher quality and patient need for self-injection with auto-injectors have evolved, demand for a high-quality plunger rose. Using Quality by Design (QbD) principles, West developed its NovaPure® components for prefillable syringe systems to provide high reliability for breakloose and glide force, dimensional accuracy and consistency, sub-visible and visible particulate control, and low parts per million (ppm) defect attributes.
The optimized functional and dimensional performance for NovaPure plungers provides improved rate of injection times and consistency when used in conjunction with 1mL long staked needle syringes and an auto-injector system.
Learn more about QbD and NovaPure components here. (link to PharmaQbD ebook)

NovaPure® and FluroTec® are registered trademarks of West Pharmaceutical Services, Inc., in the United States and other jurisdictions.
FluroTec technology is licensed from Daikyo Seiko, Ltd.