Short answer: Yes. But only if you meet the prerequisites
Most of us learn f2 through immediate-release examples. That’s why the moment an extended-release comparison comes up, even very senior teams pause:
“Are we supposed to apply the same f2 rules?”
“What about the variability – is it still 20% and 10%?”
“Do we still use the ≥85% cut-off?”
And to be fair – nearly all dissolution guidelines describe f2 prerequisites using IR logic, not MR behaviour which is completely different.
Which is why I created a simple IR vs MR f2 comparison table – the one that I use in my own work – to help you decide whether f2 is meaningful for your MR product before you run the calculation.
And no, these prerequisites are not my own interpretations.
They’re guidance-backed, including the FDA SUPAC-MR guidance document on In Vitro Dissolution Testing and In Vivo Bioequivalence Documentation (1997) – yes, it’s old, but still official.
A few practical clarifications guidance documents don’t tell you:
- Guidelines don’t explicitly mention %CV for MR, but ≤10% CV at later time-points is a generally accepted benchmark.
- You don’t apply %CV limits to the first time-point because MR products typically show higher variability at the onset – and it rarely impacts the in-vivo outcome.
- Delayed-release behaves like IR in the buffer stage but DR is still MR, so the famous “≥85% in 15 minutes -> no f2 needed” exemption does NOT apply.
If this already shifted something for you, the table will land even harder.
Read also: The f2 Similarity Factor in Dissolution
Resource Person: Pearl Pereira Nambiar