Right, robustness is a key performance criterion of an analytical method and the way DryLab has been assessing it since we made the module back in 2011, turns out to be in line with what ICH Q12 recommends in this regard.
But I think the reason for industry to turn to the Robustness Module is that it really gives you a very good understanding of how well your method will perform in routine use and in what areas of your Design Space it can be run across its lifecycle without having to face any Out-of-Specs. And this is highly relevant to many of our customers because their business model depends on their ability to yield profits in a limited window of opportunity. And for their analytical development this means that methods have to perform flawlessly in subcontractor labs in regulatory systems across six continents.
The way DryLab’s robustness assessment works is the following: first, and based on scientific theory, the Design Space and its chromatographic interactions are modeled. Next, and based on that knowledge, the MODR (Method Operable Design Region) is identified. Now, the precision of the instrumentation is taken into account and this is done by including the range of gradient sensitivity, temperature-, and pH-accuracy and also other specs that could vary… such as flow rate, for instance. This information is then added to the Drylab model to evaluate what the robustness of a work point or a work space will be.
So, once your MODR has been scrutinized in this way, the chromatographer continues and validates the robustness assessment. From the systematic way your model has progressed so far, you can now see for instance, at which point in your MODR the API will elute the earliest and at which point the latest, which will give you a certain range you can expect in routine use — which will be highly relevant for your SST (system suitability test). Also, you’ll see where in your MODR peaks-of-interest, for instance the critical peak pair, will have their lowest critical resolution. So, these strategically relevant points you then take from in-silico and run them for confirmation, fully automated, SampleSets being written and executed through DryLab’s Empower Connection, then acquired from Empower and compared to confirm the model in DryLab.
Now, the whole point of doing this with regard to Q12 is to use the software capabilities of visualizing the interactions that are going on, and to determine which parameters affect your separation in routine use, and also which won’t. This information is gathered and structured in DryLab’s Knowledge Management Document and is then the scientific basis for your Post-Approval Lifecycle Management. Flexible regulatory approaches regarding later changes would derive from, for instance, a downgrading of certain parameters from prior approval to notification.