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# FDA Sets Acceptable NITMA Level for Ritonavir Products
- URL: https://www.fdaweb.com/fda-sets-acceptable-nitma-level-for-ritonavir-products/
- Published: 2024-10-29T12:00:00.000Z
- Updated: 2026-09-14T14:45:34.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5158073

FDA has published a guidance, *Emerging Scientific and Technical Information on Ritonavir*, that sets an acceptable intake (AI) limit of 26.5 ng/day for a nitrosamine drug substance-related impurity known as NITMA (*N*\-((2-isopropylthiazol-4-yl)methyl)-*N*\-methylnitrous amide that may be present in some finished drug products containing ritonavir. The [document](https://www.fda.gov/media/183152/download?attachment&ref=fdaweb.com) says manufacturers and applicants may propose an alternative AI limit based on a safety assessment considering mutagenicity and carcinogenicity. “In the absence of justification to support a higher limit,” FDA says, “we recommend that manufacturers and applicants control NITMA such that exposure does not exceed the recommended AI limit of 26.5 ng/day.”

The agency recommends that manufacturers and applicants test their ritonavir drug products to determine whether they contain NITMA. If NITMA is detected, it says, manufacturers and applicants should perform a root cause investigation to identify the source and take appropriate measures to reduce or prevent the formation of NITMA.