N-nitroso Vonoprazan AI 96 ng/day- FDA

Dear Nitrosamines Exchange team,

I learnt that FDA has established a limit of 96 ng/day for N-nitroso vonoprazan based on below news. Can anyone help me to know how the limit has been derived, is it based on Read across or Toxicological data driven AI?

SMILES: O=S(C3=CN=CC=C3)=O

SMILES: O=S(C3=CN=CC=C3)=O

Another potential Nitroso impurity
SMILES: O=NN(CC1=CNC(C2=CC=CC=C2F)=C1)C
image

Can anybody in the regulatory aspects answer my query. How the FDA arrived N-nitroso Vonoprazan with a limit of 96 ng/day. Is it for the free base Vonoprazan or Vonoprazan Fumarate salt with a daily dose of 40 mg/day?

Dear @mnvsastry,

I surmise AI of 96 ng/day might be derived from NDMA.

However, please note this provisional relaxational given to only innovator Phathom Pharmaceuticals (VOQUEZNA) by FDA.

What limits to be considered for generic formulation?
Will it be 96ng/day or 18ng/day. NDSRI belongs to category 1

For generic formulation- I suggest it is better you either have in-silico or experimental justification that overrides CPCA category I - AI of 18/26.5 ng/day.

In case if you could not control within the limits derived from AI of 18/26.5 ng/day.