Injectability & Syringeability
Method Introduction
Injectability and syringeability analyses are commonly used to assess the feasibility of administering drug products via injection, such as using a syringe. The two terms are widely used without considering the distinct differences in their respective definitions.
The “injectability” assessment evaluates injection forces into tissue, accounting for tissue effects during the injection process. In contrast, “syringeability” refers to the ease of transferring a solution through a needle using a syringe. The assessment of “syringeability” is the more straightforward approach and is widely used in the industry to characterize liquid injectables.
During the syringeability assessment, the force needed to expel the content of a syringe is recorded. The resulting force profile is evaluated in its entirety, including the parameters “break-loose force” and “gliding force.” The break-loose force initiates the plunger movement by overcoming static friction, while the gliding force characterizes the plunger movement during injection, accounting for dynamic friction. Both forces must be achievable for the respective patient group during drug product administration. The tolerated force limits can differ substantially between target patient groups (patient compliance). Arthritis patients, for example, are considerably compromised in their ability to apply larger forces during injection.
The target patient group, the drug product properties, injection volume and choice of syringe type, as well as its components (plunger, needle size), must always be evaluated together. Therefore, it is pivotal to start the evaluation of the syringeability as early in the development process as possible.
Applications
The evaluation of syringeability (and/or possibly injectability) plays a crucial role in ensuring the applicability of liquid injectables for their intended purpose. Ideally, formulation and container closure system are developed together, starting during the early product development phases (Phase I/II).
During the formulation development process, the dose to be administered is often under investigation, influencing the target volume. Modern biopharmaceuticals are commonly developed to achieve high active substance concentrations to maintain lower injection volumes that the patient can self-administer via a pre-filled syringe (PFS) or other device. The high viscosity that usually comes with high concentrations poses challenges for formulation scientists. During the formulation development process, viscosity measurements, however, should be complemented by syringeability measurements. Because biopharmaceutical products rarely show Newtonian flow behavior, their rheological properties (governing the injection process) depend on the force applied. The effect of viscosity-reducing agents in formulation screenings is hence evaluated best by measurements of viscosity and syringeability, ideally in the most representative setting of a PFS.
Further challenges associated with combining biopharmaceuticals with PFS are related to the compatibility and stability of the combination product. Standard PFS presentations are usually siliconized, and the silicone may react directly or over storage time with amphiphilic molecules (proteins, surfactants). Therefore, ensuring that the syringeability (lubrication status of the PFS barrel) remains uncompromised until the end of its shelf life is essential.
A plateau-shaped syringeability force profile indicates a homogeneous distribution of the silicone inside the syringe barrel, and the break-loose force and gliding force must also remain within specifications. Any indication of delubrication of the syringe should also be followed up by analytical means to ensure the integrity and stability of the bioactive itself (silicone oil may induce unfolding and hence conformational as well as colloidal instabilities).
Quality and Biosafety Level
We provide all our analytical services with the highest quality standards. Experienced scientists carry out each project, and a scientific reviewer comprehensively checks every report or data presentation.
We offer this technology with the following quality and biosafety levels:
R&D level
We offer this method under R&D. Our GRP system assures the highest-quality research standards.
Up to biosafety level 2
This method can be applied to nucleic acids, viruses, cells, viral vectors, including lentiviruses and more.
Analytical Method Development, Qualification and Validation
For common sample types, we can often apply standardized methods with little setup effort. However, when needed, our experienced analytical experts create or optimize custom methods tailored to your active pharmaceutical ingredient, product type and development phase.
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