Nitrosamines

Question 1

Nitrosamine - what is the acceptable intake limit defined as?

Answer 1

An ‘acceptable intake’ (AI) limit should be calculated for individual N-nitrosamines
* Based on the ICH M7(R1) principles for “cohort of concern” substances
* AI limit corresponding to a theoretical excess cancer risk of <1 in 100,000
* Considering a lifetime daily exposure

Question 2

What is the mechanism for calculating nitrosamine limits?

Answer 2

Mechanisms provided for calculating limits where:
*More than one nitrosamine is present and
* For instances where no limit has yet been set for a particular nitrosamine

Question 3

What is the 3 step process for nitrosamines

Answer 3

3-step process required by the EMA/CHMP guidance of September
2019
Step 1 is a risk assessment. If this identifies a potential risk for
nitrosamine contamination of marketed products move to step 2
Step 2 requires confirmatory testing
* Immediate reporting of any nitrosamine detected
* Four possible scenarios (a, b, c and d) depending on the levels of nitrosamine(s) found and the applicable acceptable intake (AI) with the appropriate courses of action for each

Question 4

What are the main issues called out in the nitrosamine Q&As

Answer 4

The EMA Q&A on Nitrosamines was revised 7 times during 2022
Main issues are:
* Initial nitrosamines were contaminants
* Recently identified nitrosamines are related to the API itself
* If API contains a secondary amine group even a tiny amount of nitrite in the formulation can
lead to nitrosamine formation during shelf-life
* The toxicity of the API related nitrosamines is not known
* Cannot set acceptable intake (AI) limits
* Regulators are being super cautious
* Could lead to whole classes of medicines being withdrawn; e.g. beta-blockers

Question 5

What are the proposed changed to the nitrosamines guidance?

Answer 5

Changes proposed are:
* Guidance on appropriate process development in order to mitigate the potential presence of N-nitrosamines or other ‘cohort of concern’ (CoC) compounds
* The selected manufacturing process should be justified accordingly
* Guidance on the need to provide clear information on all the materials used in the process
Changes proposed contd.:
* Guidance on the required discussion regarding presence or formation of N-nitrosamines or other CoC compounds as well as of other potent toxins
* Clarify the new systematic approach suggested by ICH M7 on mutagenic impurities
* Guidance on the use of recycled materials
* Guidance on specific control options for N-nitrosamines or other CoC compounds as well as for other potent toxins, including possible control points and acceptance criteria
* Guidance on the need to consider formation of N-nitrosamines or other CoC compounds as well as of other potent toxins during storage

follows:
* Use of sodium nitrite or other nitrosating agents either:
 In the presence of secondary, tertiary amines or quaternary ammonium salts, or
 In combination with reagents, solvents and catalysts, which are susceptible to degradation to secondary or tertiary amines
* Use of contaminated raw materials, starting materials or intermediates
* Use of recovered materials, such as solvents, reagents or catalysts
* Use of contaminated starting materials and intermediates
* Cross-contamination from other processes
* Degradation processes of starting materials, intermediates and drug substances
* Use of certain packaging materials (it has been hypothesised that blister packing lidding foil
containing nitrocellulose printing primer may react with amines in printing ink to generate
nitrosamines, which would be transferred to the product under certain packaging process
conditions)

Question 6

What is the nitrosamine acceptable limit based on?

Answer 6

An ‘acceptable intake’ (AI) limit, based on the ICH M7(R1) principles for “cohort of concern”
substances, (AI limit corresponding to a theoretical excess cancer risk of <1 in 100,000) considering a lifetime daily exposure should be calculated for individual N-nitrosamines in human medicinal products. It also provides mechanisms for calculating limits where more than one nitrosamine is present and for instances where no limit has yet been set for a particular nitrosamine.

Question 7

What are nitrosamines?

Answer 7

N-nitrosamines contain a nitroso (N=O) group attached to an amino group via an N-N bond.

Question 8

Why are nitrosamines important?

Answer 8

Cohort of concern N-nitrosamines need to be controlled to very low acceptable intake values.

Question 9

Chemistry of nitrosamines

Answer 9

Simple nitrosamines can undergo metabolic activation to form a DNA reactive intermediate leading to formation of DNA adducts, many are potent mutagenic carcinogens

Question 10

Drug manufacture and nitrosamine production

Answer 10

N-nitrosamines can form during drug manufacture from amines when exposed to trace amounts of nitrite - present in water and most common excipients

Question 11

Nitrosamines - Acceptable lifetime intake for “standard” MI’s is

Answer 11

1.5 µg/day.

Question 12

Nitrosamines - Acceptable lifetime intake for NDEA (R1=R2=Et) is

Answer 12

26.5 ng/day

Question 13

NDSRI (nitroso drug substance related impurities)

Answer 13

• Typically larger than the known carcinogenic small nitrosamines (e.g., NDMA).
• Novel – so Acceptable Intake has to be agreed with agencies (typically conservative 18 ng/day)
• Ames tests have been used to show lack of mutagenicity (cf ICH M7) but not accepted by many HA’s. Industry proposes 1500 ng/day limit for Ames -ve
• Industry: ~20% of API’s are secondary amines
  
  • 18 ng effectively impossible to achieve for the majority of secondary amine API’s
  • Entire classes of products at risk; β-blockers, ACE inhibitors, HCTZ etc.

Question 14

• Key issues for industry are

Answer 14

• non-acceptance of –ve Ames tests
  
  • setting of inappropriately conservative limits (may lead to drug shortages)
  • agencies not always taking science and risk based approaches

Question 15

Nitrosamine guidance

Answer 15

ICH Q3A – Q3D: Requirements for assessing impurities in new drug substance and product at time of marketing application.
ICH M7: Applies throughout development.
Other ICH Guidelines referring to impurities’ evaluation:
ICH Q6 – Test procedures and acceptance criteria for new drug substances and new drug products

Question 16

Nitrosamine - Source of impurities:

Answer 16

• Drug substance synthesised via chemical route
  
  • Raw material source, Manufacturing.
  • Chemical interaction between drug substance and excipient
  • Drug product manufacturing process

Question 17

Nitrosamines - Unwanted/extraneous chemicals or elements that remain within API or drug product:

Answer 17

• Starting materials
  
  • Intermediates
  • Enantiomers
  • Mutagenic impurities
  • By products
  • Residual solvents
  • Elemental impurities
  • Extractables & leachables
  • Residual reagents (organic & inorganic)
  • Degradation products (API /Drug Product)
  • Impurities arising from excipients (incl. preservatives & antioxidants)
  • Processing aids

Question 18

Nitrosamines - Impurity Qualification

Answer 18

process of acquiring & evaluating data that establishes biological safety of impurity at concentration and consequent dose to be administered in humans.
* Unqualified Impurity – an impurity present in clinical batches below the qualification threshold and as such is acceptable without safety data, and may or may not be identified.
* Investigational product must arrive at marketing submission with specs aligned with ICH Q3A & Q3B

Question 19

Nitrosamines - Durational limit

Answer 19

• The standard ICH limits don’t apply during clinical development (except for mutagenic)
• Since 2015, in early clinical development, AZ have used the durational limits approach proposed by Harvey et al 2017 to support levels of up to 0.7%/5mg (whichever is lower) for clinical trials up to 6 months duration

Question 20

Sources of nitrosamine generation

Answer 20

• Formed during API processing under certain processing conditions and with certain raw materials, starting materials, intermediates present.
• Use of sodium nitrite, or other nitrites, in the presence of secondary or tertiary amines.
• Contaminated raw materials – recycled solvents, reagents, catalysts
• Contaminated starting materials from Vendors, including intermediates using processes that lead to nitrosamine formation.
• Formed from residual amines present in API with nitrosating impurity (typically nitrite) in the excipient.

Question 21

Nitrosamines - what is a specification

Answer 21

• A specification is fully defined in ICH Q6a. Essentially it is a list of tests and acceptance criteria which ensures the safety, efficacy, manufacturability and stability of a drug substance or drug product.
• Specifications evolve during clinical development, and at the time of marketing may include limits based upon manufacturing knowledge as well as scientific justification
• These IAG presentations will focus on those clauses which ensure safety during development and provide a scientific framework for the limits which may be applied
• Impurity clauses should always be reviewed in light of potential impacts on downstream processing and the final product in addition to any safety concerns

Question 22

Nitrosamines - organic impurities

Answer 22

• Organic impurities in the context discussed refers to those focused upon in Q3A/Q3B:
  
  • Organic impurities generated during the synthesis of an API
  • Degradation compounds in the drug substance or drug product
• The limits discussed assume the impurities are non mutagenic

Question 23

Nitrosamines - impurity qualification

Answer 23

• ICH Q3A/B guidelines specify thresholds for when impurities are reported, identified and qualified – but not applicable during clinical development
• Qualification is “The process of acquiring and evaluating data that establishes the biological safety of an individual impurity or a given impurity profile at the level(s) specified”
• Qualification of impurities is usually achieved during the 1-month studies and is based on the dose of the impurity at the NOEL/NOAEL* in rats or dogs i.e., the level of impurity present in toxicology studies are considered qualified (up to level tested)
• Qualification can also be achieved if impurities are significant animal and/or human metabolites
• Higher/lower levels acceptable if justified / necessary (case-by-case) e.g., consider patient population, risk/benefit
• Higher levels may be used during clinical development – see next section of presentation
• If proposed specification level is not qualified or justified – impurity qualification toxicology studies may be required (worst case scenario!!)
• See ICH Q3A, ICH Q3B and ICH Q6A

AstraZeneca considers that qualification based on mg/kg provides adequate assurance of safety for patients:
* Standard practice across the pharmaceutical industry (surveys and publications)
* ICH Q3A does not define a requirement to apply any adjustment factors (such as BSA)
* Limits in ICH Q3A are based on 1 mg per day as a negligible risk of harm for lifetime (many publications to support this)
* A conservative body weight of 50 kg is used for the assessment of impurities (compared to 60 kg starting doses in the clinic)
* The NOAEL of the DS provides an additional safety margin for the predicted NOAEL for an impurity which is directly proportional to the % of impurity in the DS (e.g., imp at 1% has an assumed 100-fold safety margin relative to the API at the qualified level)
* Only one guidance refers to a Human Equivalent Dose (HED): US FDA Guidance “Estimating the maximum safe starting dose in initial clinical trials for therapeutics in adult health volunteers” which is for active pharmaceutical ingredient (API) starting dose, to provide an additional safety factor for volunteers in clinical trials.

• The standard ICH limits do not apply during clinical development (except for mutagenic impurities)
• These principals cover all phases of development and clinical study duration:
• ICH Q3A concept is lifetime exposure to 1 mg/day of a non mutagenic impurity is safe, this is supported by databases and analysis of tox data
• The Harvey paper took the 1 mg/day as a threshold for clinical development, and used a modified Haber’s Law calculation to support the higher qualification limits of 0.7%/5mg for up to 6 months duration
• ICH Q3A and Q3B contain limits which vary with dose of active, therefore need to cover different dose ranges as well as different clinical study durations
• ICH M7 which applies throughout clinical development also includes limits which vary with duration
• Identification limits have implications for control of mutagenic impurities, so these remain as per ICH

Question 24

Nitrosamine - General principles for setting specification

Answer 24

• A drug substance or drug product specification should fulfil two basic criteria:
• 1) Ensure that, with the exception of API related side effects, the material is safe to dose in to humans and does not degrade to unsuitable levels upon storage.
• 2) Ensure that the material behaves as it should in drug product manufacturing and in vivo with respect to pharmacokinetics.
• Impurities play a significant role within the establishment and evolution of specifications as they can impact safety, manufacturability and product performance.

Question 25

API Product performance

Answer 25

• When drug substance or product have undergone a change in manufacturing route or process, factors potentially affecting drug stability, and drug product performance in manufacturing or in vivo need considering.
• Important impurity aspects to consider:
• Change in solvent profile: can affect both DS and DP stability, particularly where solvent forms inclusion complexes. Can also affect smell and colour.
• Change in organic impurity profile: Occasionally (although rarely), changes in impurity profile can affect both manufacturing and dissolution profiles
• Change in catalyst (elemental impurities): Some residual metals can induce radical mediated oxidation in catalytic amounts. Consider information gathered from forced deg studies etc as a reference source.
• Please note, other aspect such as solid state (not impurity related) may also influence the drug product performance.

Question 26

Controlling Nitrosamines

Answer 26

• N–nitrosamines, are a potentially mutagenic class of impurities that may pose a risk of cancer when individuals are exposed to them, above acceptable levels, for extended periods. In recent years, nitrosamines have been detected in various widely marketed medicines, examples include varenicline, metformin, ranitidine, and the sartan class of medicines, which has led to voluntary product recalls from the market. Maintaining the safe production of critical medicine is a global priority for the pharmaceutical industry. To mitigate the risk of nitrosamines, regulatory bodies and health authorities are emphasizing the importance of identifying, monitoring, and controlling nitrosamine impurities in active pharmaceutical ingredients (APIs) and other raw materials. Analytical testing plays a vital role in controlling nitrosamines in both marketed medicines and drugs in development.