25 September 2020 | Views
Nitrosamine impurities may be formed during API processing under certain processing conditions
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Recently, a concern raised by regulatory agencies on the presence of nitrosamine impurities observed in drugs such as angiotensin II receptor blockers (ARBs) viz. Valsartan, and other class of drugs (e.g. Ranitidine, Nizatidine, and Metformin) that has created a havoc in pharma industry as this compelled the pharma companies to recall many lots of Finished Goods from the market.
Nitrosamine is a class of compound having N-nitroso (R1-N (-R2)-N=O) functional group as a part of their chemical structure. These molecules are potent genotoxic and are classified as probable human carcinogens by the International Agency for Research on Cancer (IARC). Very small exposure of these impurities can lead to cancer.
Although they are also present in some foods and drinking water supplies, their presence in medicines is nonetheless considered unacceptable.
European Medicine Agency (EMA) has finalised a review under Article 5(3) of Regulation (EC) No 726/2004 in June 2020 to provide guidance to marketing authorisation holders on how to avoid the presence of nitrosamine impurities in human medicines.[1]
FDA has also issued guidance on “Control of Nitrosamine Impurities in Human Drugs” which recommends steps that should be taken by API and Drug Products manufacturers to detect, reduce or prevent the presence of nitrosamine impurities in APIs and finished drugs.[2]
Potential Source of Nitrosamine Impurities:
Nitrosamine impurities can originate from different sources related to the manufacturing process (including raw materials, reagents, reactants and solvents used in the process), chemical processing reaction conditions, use of recycled solvents and the chemical structure of the API.
Additionally, several external factors, such as packaging or storage conditions, can intensify nitrosamine contamination.
Potential root cause for the formation of Nitrosamine impurities:
Nitrosamine impurities may be formed during API processing under certain processing conditions and in the presence of some types of raw materials, starting materials, and intermediates. These impurities may not be fully purged in subsequent steps of the API manufacturing process and get incorporated into the drug substances or drug product.
Risk assessment and mitigation:
API and Drug Products manufacturers should perform a comprehensive risk assessment for already approved /marketed products, and pending for approval applications to identify the potential for nitrosamine impurities. If a risk of nitrosamine impurities is identified, confirmatory testing of batches should be conducted using sensitive and appropriately validated methods. If the risk assessment determines that there is no potential for nitrosamine impurities, there is no need to take further action.
If a nitrosamine impurity is detected, API manufacturers should investigate the root cause. They should implement changes in the manufacturing process to reduce or prevent nitrosamine impurities.
A risk-based approach can be adopted to prioritize the evaluations followed by confirmatory testing (if the risk evaluation would indicate that testing would be required). Following factors should be considered for prioritization:
Following factors should be considered during risk assessment:
Purging factors, if known, can be useful to review the risk
Finally, absence of nitrosamine impurities should be verified by testing a representative number of samples of the relevant starting material, intermediate, API or finished product and the number of batches/samples tested should be scientifically justified. Any API batch containing a nitrosamine impurity above the interim acceptable limits should be recalled, if distributed, or dispositioned as not suitable for use in DP.
Corrective Actions for mitigation:
If presence of nitrosamine impurities is confirmed, then API / Drug product manufacturers are required to modify the processes so they do not produce any nitrosamine impurities. Following can be considered for change in process:
Limits for Nitrosamine impurities
The Acceptable Intake (AI) limit for nitrosamine is a daily exposure to a compound such as NDMA, NDEA, NMBA, NMPA, NIPEA, or NDIPA that approximates a 1:100,000 cancer risk after 70 years of exposure. The conversion of AI limit into ppm varies by product and is calculated based on a drug’s maximum daily dose (MDD) as reflected in the drug label (ppm = AI (ng)/MDD (mg)).
Test methods to be developed should be sensitive enough to detect these impurities at very low levels. Limits proposed for some of the nitrosamine impurities in Valsartan and their LOD achieved through different test methods are provided below:
Nitrosamine Impurity |
Limit in Valsartan |
LOQ achieved by Test method |
|
UHPLC/MS/MS |
GC/MS/MS |
||
NDMA |
0.3ppm |
0.2ppm |
0.08ppm |
NDEA |
0.08ppm |
0.04ppm |
0.04ppm |
AI Limits for Nitrosamine impurities in Drug Products are provided below:
Nitrosamine Impurity |
Acceptable intake (AI) Limit (ng/day) |
|
NDMA |
96 |
|
NDEA |
26.5 |
|
NMPA |
26.5 |
|
NDIPA |
26.5 |
|
Analytical Test Methodology for nitrosamine impurities:
API and Drug Product manufacturers are responsible for developing and using suitable methods to detect and limit unacceptable nitrosamine impurities, including any new impurities that may arise when they make changes to their manufacturing processes.
The typical tests for API purity, identity, and known impurities are unlikely to detect the presence of a nitrosamine impurity. Further, each failure mode could result in different nitrosamines, different amounts, or undetectable amounts of nitrosamine impurities in different batches from the same process and API producer.
Analytical methods developed by FDA and EDQM for determination of nitrosamine impurities in sartans can be used as a starting point for the development and validation of analytical methods appropriate for other APIs.
The following technical aspects should be considered during development of analytical methods:
Recommended Timeline for Risk Assessment, Confirmatory Testing, and Submission of Required Changes:
For Approved / Marketed Products:
Drug Product manufacturers should conclude a risk assessment of approved or marketed products within 6 months of publication of this guidance (Sep 2020). Confirmatory testing should start as soon as the risk of nitrosamine is identified from the risk assessment and should begin immediately for products considered at high risk.
For Pending Applications:
Applicants should conduct a risk assessment for nitrosamine impurities in APIs and drug products and conduct confirmatory testing if needed, and changes to the DMF or application should be submitted as quickly as possible.
If confirmatory testing finds nitrosamine levels above the LOQ but is within the AI limit, the applicant should amend the application as appropriate. The Agency will work with the applicant to resolve issues during the review cycle or immediately after approval, and before distribution, if determined to be necessary by the Agency.
Dr Prabha Bhandari, V.P. Regulatory Affairs, Council for Healthcare and Pharma (CHP)
[1] https://www.ema.europa.eu/en/human-regulatory/post-authorisation/referral-procedures/article-53-opinions
[2] https://www.fda.gov/media/141720/download