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The Best Practice for an Accurate Estimation of the Injection force of Protein Therapeutics Avoiding Common Pitfalls

Injection GIF

Injectability is one of the screening criteria in determining the candidacy of protein therapeutics. It is determined by the required force during injection.

For a fixed syringe geometry and delivery
rate, the required injection force is solely determined by the viscosity of the therapeutics. (see Higher Shear Viscosity Measurement and Injectability Application Note).

Therefore, candidate protein therapeutics are scrutinized if their viscosity is higher
than the pre-set threshold. The cut
-off viscosity generally ranges from
20 to 40 mPa-s depending on
the device. However,
this type of generalization without specifying the shear rate could potentially lead to a false negative determination of
an otherwise excellent therapeutic
resulting in a significant financial loss during development. In order to avoid
this pitfall, download the application note to learn what to do and what not to do when it comes to selecting your proteins.


  • Viscosity
  • Syringeability
  • Protein Therapeutics
  • High Shear 
  • Injection Force
  • Shear Thinning
  • Newtonian


1. Are protein formulations non-Newtonian?

Every sample can be quite unique depending on what it is formulated of. In general, we have seen most proteins to show non-Newtonian behavior. As most samples are, proteins are quite complex and when it comes to being in formulation, manufacturing, or just in general a Protein Scientists, you may see this uphill battle where you need to reduce the viscosity of the proteins, while maintaining efficacy, and also reducing as much of the physical contributions injecting your proteins could have to a patient. 

When a sample shows non-Newtonian behavior, it is recommended to test the sample at a wide shear rate range (at least 25%, 50%, and 75% full scale with RheoSense viscometers). Some proteins may actually show shear thinning behavior at much higher shear rates, while other proteins show a nice shear thinning curve over standard shear rates. It is all different so it is important for you to review and understand the scope and behavior of your special protein. 

To learn about the differences between Newtonian vs. non-Newtonian, check out our educational page here: https://www.rheosense.com/applications/viscosity/newtonian-non-newtonian

2. What benefits does VROC Technology have over others?
  1. VROC® technology works in a fully enclosed system. This is beneficial as it will not be affected by air causing your viscosity values to be higher or lower and you will not see any strange behavior of your sample as air interacts during measurement.
  2. We provide dynamic viscosity results or what is also commonly accepted in the pharma industry as "First Principle" and also in the general industry as "true viscosity." Why get apparent viscosity readings when your data needs to be real and accurate? 
  3. We have direct control of shear rates. This is beneficial especially when we determine injectability. Understanding the scope of how your sample behaves at different shear rates will also mimic the final product in its environment.

Learn more via http://www.rheosense.com/technology 

About the Viscometer

Learn more about the automated viscometer that compliments Clariti™, VROC® initium.

  • 26 µL of Sample
  • Sample Retreival initium (no bdg)
  • Sample Recovery
  • Measurement temperatures 4 - 70 ºC
  • Fully automated system
  • 40 Vial Rack/96 Well Plate
VROC initium