What Are Nitrosamine Impurities And How, Where, and At What Limits Must They Be Controlled In Pharmaceuticals | Learn With Case Studies And FAQs - PharmaGuru | Global Pharma Training, Certifications & Expert Blogs

Q: 1. What are Nitrosamines?

Nitrosamines are organic chemical compounds that contain the nitroso functional group (–N=O) bonded to a secondary or tertiary amine (NR₂). Because many of these compounds are mutagenic and carcinogenic in animal studies, they are classified as “probable human carcinogens” by regulatory agencies. In the pharmaceutical context, “nitrosamine impurities” are unwanted trace amounts of nitrosamines present in drug substances (APIs), in excipients, in drug products (formulations) or generated during storage or manufacturing

Question 1

1. What are Nitrosamines?

Accepted Answer

Nitrosamines are organic chemical compounds that contain the nitroso functional group (–N=O) bonded to a secondary or tertiary amine (NR₂).
Because many of these compounds are mutagenic and carcinogenic in animal studies, they are classified as “probable human carcinogens” by regulatory agencies.
In the pharmaceutical context, “nitrosamine impurities” are unwanted trace amounts of nitrosamines present in drug substances (APIs), in excipients, in drug products (formulations) or generated during storage or manufacturing

Question 2

2. How, where, and at what level should Impurities be controlled?

Accepted Answer

LC-MS and GC-MS are widely used to control nitrosamine impurities. Nitrosamine impurities coming from raw materials should preferably be controlled in the raw material. Nitrosamine impurities formed in the process should preferably be controlled at the same stage. Nitrosamine impurities that cannot be controlled in intermediate stages or in the (N-1) stage, or in the raw material stage that must be controlled in the API stage. Nitrosamine impurities formed due to degradation of the API must be controlled in the API stage.

Question 3

3. How are Nitrosamines formed in pharmaceuticals?

Accepted Answer

Nitrosamines may form in pharmaceuticals due to the following reasons:
a. Use of Nitrate, Nitrites and certain amines in the process.
b. Presence of DMA (dimethyl amine) in DMF (dimethyl formamide (if DMF is a component of the sources of secondary, tertiary, and quaternary amines that can form nitrosamines.

Question 4

4. What are the 7 nitrosamine impurities?

Accepted Answer

The following are the 7 nitrosamine impurities
1. N-Nitrosodimethylamine (NDMA)
2. N-Nitrosodiethylamine (NDEA)
3. N-Nitroso-N-methyl-4-aminobutanoic acid (NMBA)
4. N-Nitrosoisopropylethyl amine (NIPEA)
5. N-Nitrosodiisopropylamine (NDIPA)
6. N-Nitrosodibutylamine (NDBA)
7. Nitrosomethylphenylamine (NMPA)

Question 5

5. What products contain nitrosamines?

Accepted Answer

Products in whose synthesis azide or nitrite are used, such as metronidazole, cilostazol, cefazolin, etc. and sartans having a tetrazole ring, such as valsartan, irbesartan, losartan, olmesartan, candesartan etc,. are prone to nitrosamines.

Question 6

6. What are common sources of nitrosamines?

Accepted Answer

Nitrosamine may be present in processed meat, alcoholic beverages, cosmetics, cigarettes and treated and drinking water. Nitrosamine may form in the synthesis of pharmaceuticals where Nitrates, Nitrites and certain amines are used.

Question 7

7. How do you remove nitrosamines?

Accepted Answer

Avoid the reaction conditions that may produce nitrosamines whenever possible; When not possible, demonstrate that the process is adequately controlled and capable of consistently reducing nitrosamine impurities through appropriate and robust fate and purification studies. Use bases other than secondary, tertiary, or quaternary amines (when possible) if ROS (route of synthesis) conditions can form nitrosamines.

Question 8

8. What do nitrosamines do to your body?

Accepted Answer

Nitrosamines damage DNA, which can cause cancer. This is why nitrosamines are genotoxic in nature and fall under the group of concern (COC).

Question 9

9. What are the symptoms of nitrosamines?

Accepted Answer

N-nitrosomethylamine can cause liver damage

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By Dr Pramod Kumar Pandey - April 5, 2025

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