Sitagliptin NTTP nitrosamine impurity maximum active intake level 37ng to 246.7 ng/per day

Yes dear, this change is approved in EMA and FDA as well.


Hi Alaaelkazak

Can you kindly share EMA and FDA approved NTTP AI limit from 37 ng to 246.7 ng approved letter or any kind of communication?

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Interesting choice to use.

Propyl gallate is not without its issues from a formulation and analytical perspective.

Also, it was included in one of the original papers looking at the capability of scavengers, but didn’t progress very far in the paper, as in the systems and molecules that were being looked at I don’t remember it having much scavenging activity.

Scavengers do seem to be very nitrosamine specific! What works for one molecule may not work for another.

Is the decrease in shelf life because there isn’t enough data to support maintaining three years, and as real-time later stability time points become available it will be extended again, or because, even with the propyl gallate, the nitrosamine goes above the permitted level after 2 years?


Hi MarkS,

It’s a good point. The reason why they selected propyl gallate for their products is not described in the document.

As I wrote in the previous post, their policy is to keep the amount of NTTP less than 37 ng/day. The AI was published in May 2022 in EMA and the change application was scheduled in October 2023. Their data might only cover two years from one-year stability tests, despite the original being three years.

Most likely it was left out of the paper on purpose, to avoid giving tips to the competitors, or even maybe if they wanted to patent the new formulation? I would not have expected MSD to publish their mitigation action prior to it being 100% implemented

Already Sita+ Met ER tablets have propyl gallate in Sitagliptin portion which is drug layering approach on metformin matrix tablets.



PFA : Science direct article which refer use of antioxidant to reduce Nitrosamine impurity level.

N-nitrosamine Mitigation with Nitrite Scavengers in Oral Pharmaceutical Drug Products

Science Direct Nitrosamine.pdf (638.8 KB)