What is the study about?
There is a need for developing new technologies to enable sub cutaneous (SC) delivery of larger volumes and higher concentrations in relation to SC treatments being preferred over IV. This study is about investigating large and fast SC delivery in Göttingen Minipigs.
What is the purpose of the study?
Testing the feasibility of SC delivery of various volumes and at different flow rates in the Göttingen Minipigs.
Why is it important?
A lot of effort is being put into designing large volume autoinjectors and novel formulation technologies for SC delivery. These devices and technologies need to be tested to ensure safety and functionality. Such testing should be performed in animal models before tests in humans are to be initiated.
What makes this study particularly interesting?
There are certain physical limitations to autoinjectors, that limits the force which can be used for delivering the drug into the SC space. Highly concentrated formulations bring high viscosities, which require high forces. Imagine trying to force syrup through a needle and you need to push 5 ml through in 20 seconds – it will require substantial force… and the more force you add to the mix, the more risks will follow. This study investigated how much force it required to inject saline at different very fast flowrates.
Which challenges have you met during the study?
The usual suspect, namely biology. The SC space is a multiplex of different structures with varying parameters. Unfortunately, it’s not a homogenous place like the blood pool you access via IV. So, there’s an inherent variation in the output data that grows once you push the boundaries of speed and volume. Especially the position of the needle point is important, as just the tiniest obstruction of the lumen of the needle has huge implications for the output data.
How do you recommend going about species selection?
When it comes to SC delivery, the Göttingen Minipig is the golden standard, as its skin is very comparable to human, especially when it comes to the SC space. Two things to consider however is the presence of musculus panniculus carnosus that can interfere in the SC and the hair follicles that can cause an issue for autoinjectors if the needle hits one dead on.
Any learnings you would like to share?
Expect variation in data and take care not to investigate too many things at the same time.
Three different treatments (flow rate and volume) and the respective pressure required for injection over time.
Top left: 3D images from before and after injection.
Top right: Topographic heatmap of bleb height.
Bottom: Topographic development of bleb over time after injection.
