5.11. Nitrosamine Impurities

1 Page 1 of 18 Nitrosamine Impurities In July 2018, nitrosamines became popular when there was recall of angiotensin II receptor blocker (ARB) medicines, known as sartans , due to the presence of an impurity, N-nitrosodimethylamine (NDMA). Valsartan and Losartan are the worst affected and several lots of these products have been recalled globally. N-nitroso compounds are among the structural groups having high potency mutagenic carcinogens in several animal species, and some are classified as probable or possible human carcinogens referred to as the cohort of concern" in ICH M7(R1): Assessment and Control of DNA Reactive (Mutagenic) Impurities in Pharmaceuticals to Limit Potential Carcinogenic Risk. So, these Impurities must be controlled at or below the acceptable cancer risk.

2 This family of Impurities has potential for Genotoxicity, hence pose an additional safety concern to patient and as a result of the potential toxicity associated, it is recommended to take steps to control and limit their presence in pharmaceutical materials. This chapter has been introduced in IP to provide guidance for the control of Nitrosamine Impurities in order to ensure that the potential presence of nitrosamines in drug substances and drug products is identified, assessed and controlled. Formation of Nitrosamines: Nitrosamines are a group of compounds having the chemical structure of nitroso group bonded to an amine (R1N(-R2)-N=O). They are formed by reaction between secondary, tertiary, or quaternary amines and nitrous acid (nitrite salts under acidic conditions) by nitrosating reaction. Nitrosamine Formation Reaction Table 1.

3 Nitrosamines Found as Contaminants in Drug Substances and Drug Products Common Name and Chemical Name Acronym CAS # Structure Chemical Formula Molecular Weight Nitrosodimethylamine N-Methyl-N-nitrosomethanamine NDMA 62-75-9 C2H6N2O Nitrosodiethylamine N-Ethyl-N-nitrosoethanamine NDEA 55-18-5 C4H10N2O Nitrosodiisopropylamine N-Isopropyl-N-nitrosoisopropylamine NDIPA 601-77-4 C6H14N2O Page 2 of 18 Common Name and Chemical Name Acronym CAS # Structure Chemical Formula Molecular Weight Nitrosoethylisopropylamine N-Ethyl-N-nitroso-2-propanamine NEIPA 16339-04-1 C5H12N2O Nitrosodibutylamine N-Butyl-N-nitroso-1-butanamine NDBA 924-16-3 C8H18N2O Nitrosomethylphenylamine N-Methyl-N nitrosophenylamine NMPA 614-00-6 C7H8N2O Nitrosomethylaminobutyric acid 4-[Methyl(nitroso)amino] butanoic acid NMBA 61445-55-4 C5H10N2O3 Source of Nitrosamines There are a number of pathways by which nitrosamines can be introduced into or generated as Impurities in pharmaceutical drug products.

4 Specifically, nitrosamines are formed by chemical reaction of secondary, tertiary or quaternary amines with nitrites under acidic conditions. Under these conditions, nitrite salts may form nitrous acid, which can react with an amine to form a Nitrosamine (See Formation of Nitrosamines). Some examples of the reported sources or pathways leading to the generation of nitrosamines identified empirically or reported include (but are not limited to) the following: 1. Nitrosating Agents +NO Nitrosonium Ion Phenol-NO Nitrosyl Phenol Halide-NO Nitrosyl Halide HNO2 Nitrous Acid ONO-NO (N2O3) Nitrous Anhydride CNS-NO Nitrosyl Thiocyanate (N2O4) Dinitrogen Tetraoxide (SO4-ClO4-) Nitrosyl Sulfate/Perchlorate 2. Sources of Secondary, Tertiary, Quaternary Amines and nitrite salts that can form nitrosamines.

5 The API (or API degradants), intermediates, or starting materials may contain secondary or tertiary amine functional groups. Tertiary and quaternary amines used as reagents in the synthesis of APIs may contain other amine Impurities . Tertiary amines, such as triethylamine, have been shown to contain low levels of other secondary amines (such as dipropylamine and isopropyl ethylamine). Secondary and tertiary amines may be present as Impurities or degradants formed by dealkylation of quaternary amines. Page 3 of 18 The drug substance itself, which may degrade under some conditions resulting in the formation of nitrosamines ( , ranitidine). Impurities in the container closure system for the finished drug product, which may include Impurities capable of forming nitrosamines, especially if associated with materials containing amines and potential sources of a nitrosating agent ( , nitrite, nitrocellulose).

6 3. Contamination in Vendor-Sourced Raw Materials In contaminated vendor-sourced materials, like starting materials and raw materials, Nitrosamine Impurities can be formed. Nitrosamine contamination takes place when fresh solvents (o-xylene, toluene, and methylene chloride) were contaminated during shipment from vendors ( , during transfer between storage vessels), Cross-contamination of starting materials may takes place if they are manufactured at sites where Nitrosamine Impurities are produced in other processes. Sodium nitrite present in starting materials reacts with amines under acidic conditions to form nitrosamines. Special attention should be given to the formation of nitrogen-containing heterocycles by employing azide followed by quenching with nitrous acid to remove excess azide.

7 Impurities like secondary or tertiary amines have been reported in some raw materials and in fresh solvents like toluene. 4. Recovered Solvents, Catalysts, and Reagents as Sources of Contamination Due to the presence of residual amines (such as trimethylamine or diisopropylethylamine), recovered solvents, catalysts, and reagents may pose a risk of Nitrosamine Impurities . Raw materials can be contaminated, if adequate cleaning of equipment between customers, or between different materials, is not carried out or is not validated as capable of removing each impurity of concern. 5. Lack of Process Optimization and Control Potential source for the formation of Nitrosamine Impurities are lack of optimization of the manufacturing process for APIs when reaction conditions such as temperature, pH, or the sequence of adding reagents, intermediates, or solvents are inappropriate or poorly controlled.

8 A risk assessment should be conducted to determine the materials that contribute to the potential for inclusion of nitrosamines in the drug products. All potential sources for the introduction of nitrosamines should be considered in the risk assessment including the drug substance, excipients, water, solvents, the manufacturing process, packaging components, and formation on stability. Table-2. Some of the identified risks associated with several of the potential sources of nitrosamines are as follows: Potential sources of Nitrosamines Observed Risk Solvents Presence of residual dialkylamines or tri-substituted amines that can degrade to form intermediates that can further react with nitrosating agents. Presence of nitrites or other nitrosating agents. Presence of acid.

9 Limited controls/specification limits for recycled solvents. Poor quality solvents Water Presence of residual dialkylamines or Impurities that can degrade to form dialkyl amines Presence of acid and nitrosating agents. Excipients Presence of nitrites or other nitrosating agents and/or Nitrosamine Impurities Drug substance Use of sodium azide in the synthesis followed by use of nitrites in acidic medium (nitrous acid) for quenching excess azides Use of di- or tri-alkylamines and amides ( , dimethyl-formamide [DMF], Page 4 of 18 dimethylamine [DMA], triethylamine[TEA], N- methylpyrrolidone [NMP]) in the presence of nitrites and acid media. Use of recycled solvents that may contain Nitrosamine or their precursors. Use of sanitized water ( , chloramines) Insufficient purification. Degradation of drug substances containing functional groups that can then participate in nitrosation reactions.

10 Manufacturing process Contamination. Use of recycled solvents that may contain Nitrosamine or their precursors. Presence of nitrous oxides in air used to dry the drug substance or drug product. Carryover of relevant reactive species into subsequent steps. Drug Product (Including stability) Secondary, tertiary, or quaternary amine group in molecule of drug substance. Presence of nitrate counter ions (potentially containing nitrite as an impurity). Potential reactions within the formulation matrix during stability/shelf life ( , presence or generation of acidic conditions, moisture and heat). Container-closures Packaging materials containing vulnerable amines that might react with nitrosating agents present in the packaging material itself ( , amines in inks reacting with nitrocellulose print base) Nitrosamine Risk Assessments Development of a Control Strategy In order to maintain the Nitrosamine Impurities at or below the level of acceptable intake, certain level of control is needed by the drug product manufacturer to determine the potential formation or contamination with Nitrosamine Impurities (Manufacturers may refer to the ICH guidance for industry Q9 Quality Risk Management).