Nitrosamine Impurity: Management of Unwelcome Guest in Pharma Market

 

Ajay I. Patel1, Anjali K. Mandavia1*, Amit J. Vyas1, Ashok B. Patel2

1Pharmaceutical Quality Assurance Department, B. K. Mody Government Pharmacy College,

Rajkot, Gujarat, India.

2Government Pharmacy College, Gandhinagar, Gujarat, India.

*Corresponding Author E-mail: anjali.mandavia1@gmail.com

 

ABSTRACT:

Nitrosamine impurities have been detected in various pharmaceutical products in recent days. Various sartans, ranitidine, nizatidine and metformin have been recalled from the markets due to the high limit of nitrosamine impurities. When assessing the danger of human cancer, pharmaceutical products ability to regulate potentially mutagenic and carcinogenic contaminants is crucial. The risk of their mutagenic and carcinogenic potential has increased with the recent finding of nitrosamine impurities in various commercially available medications. Nitrosamine is the substance deemed to be a potential human carcinogen by the International Agency for Research on Cancer (IARC). Impurities in nitrosamines have been shown to be mutagenic and carcinogenic; even very low exposure levels to these impurities can cause cancer. These impurities may be created by a reagent, catalyst, solvent, or raw materials employed in the manufacturing process and end up in drug substances or drug products. Angiotensin II receptor blocker (ARB) medications with nitrosamine impurities have caused widespread health problems. Risk management of nitrosamine impurity is necessary to control the level of this impurity in drug substance, drug product and APIs. By using risk management tools like fishbone diagram which is used to identify and organize the possible sources of nitrosamines in medicines. For detection of nitrosamine impurity different countries develops their own analytical methods.

 

KEYWORDS: N-nitrosamine impurity, Carcinogenic, Risk assessment, Interim limits, Analytical method.

 

 


INTRODUCTION:

Molecules with a nitroso functional group are included in the class of chemical substances known as N-nitrosamines, commonly known as nitrosamines. These N-nitroso substances are part of a class of high potency mutagenesis carcinogens known as the "cohort of concern." Nitrosamines had previously been found in foods such as cured and grilled meats, dairy products, vegetables, and beverages as well as drinking water sources, tobacco smoke, cosmetic items, and beverages.

 

 

 

 

 

However, it wasn't until the middle of 2018 that the EU authorities learned that nitrosamine impurities were present in sartan APIs. Meanwhile, reports of these contaminants in, ranitidine1,2,3, metformin4,5,6, pioglitazone7,8,9 and rifampicin APIs and/or pharmaceutical products have also been made.10

 

 

Figure 1. Structure for N-nitrosamine compound 2

 

The name "nitrosamine" refers to a set of molecules with the chemical formula R1N (-R2)-N=O, where R1 and R2 are alkyl or aryl groups, as shown in Figure 1. A nitrosating reaction between amines (secondary, tertiary, or quaternary amines) and nitrous acid can result in the chemicals (nitrite salts under acidic conditions).11

 

 

Figure 2. Formation of nitrosamines in pharmaceuticals. Common factors contributing to nitrosamine formation12

 

Secondary amines, amides, carbamates, derivatives of urea with nitrite, and other nitrogenous substances react with nitrogen in the +3 state to generate the family of carcinogens known as nitrosamines. In the world of consumer goods and pharmaceuticals, nitrosamines are one of the frequent and unwelcome guests—the one who shows up uninvited, consumes our resources, and just won't leave. This is due to the common nature of the precursors and the ease with which nitrosationreactions occur under acidic pH.13

 

Figure 3. Representative Reaction to Form Nitrosamines11

 

TYPES OF NITROSAMINE IMPURITY:

FDA has identified seven nitrosamine impurities that theoretically could be present in drug products:11

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.     N-nitrosomethylphenylamine (NMPA)

 

Five of them (NDMA, NDEA, NMBA, NIPEA and NMPA) have actually been detected in drug substances or drug products.

 

The FDA discovered two more nitrosamine impurities in rifampin and rifapentine in August 2020. These were 1-methyl-4-nitrosopiperazine (MNP) and 1-cyclopentyl-4-nitrosopiperazine (CPNP), respectively. Investigations are ongoing to determine where the MNP and CPNP in these medicinal products came from.14Rifampin is an antibacterial medication used to treat serious illnesses in addition to tuberculosis. The FDA recently learned that some batches of rifampin, which was MNP, contained nitrosamine impurities (1-methyl-4-nitrosopiperazine).15

 

Figure 4. Structure of MNP and CPNP15

 

Presence of nitrosamine impurities in certain drug products11

The FDA has been looking into the nitrosamine contaminants found in several medication products. Since 2018, it has been discovered that a number of medication items, including ARBs, ranitidine, nizatidine, and metformin, contain unsafe amounts of nitrosamines. The FDA discovered NDMA in the ARB valsartan in June 2018. The Agency's research revealed that certain lots of valsartan and a few other ARB medication items from various manufacturers had unacceptably high amounts of nitrosamines. FDA discovered an inadequate quantity of NDMA in some popular heartburn medications like ranitidine, also known as Zantac, and nizatidine, also known as Axid, in September 2019.FDA discovered NDMA in metformin in February 2020, although no quantities were discovered that were higher than the permitted ingestion limit. The FDA discovered an inappropriate quantity of NDMA in the formulation of extended release metformin in May 2020.

 

FORMATION OF NDMA IN SARTANS:

FDA and EMA announced in July 2018 that NDMA, a carcinogenic contaminant, has been discovered in some generic drugs, particularly those in the "sartan" family. Only sartans with a tetrazole ring in their structure can produce nitrosamine.16 The CHMP discovered that the usage of dimethylformamide (DMF) and other chemicals during the production process was the cause of the presence of NDMA in sartan APIs with a tetrazole ring. Under some circumstances, the solvent DMF can break down to produce trace amounts of dimethylamine (DMA). This amine then reacts with sodium nitrite (NaNO2), another substance utilised in the production process, in an acidic environment to create NDMA.17

 

Figure 5. Decomposition of DMF to form NDMA 16

 

Formation of NDEA in valsartan:

The sartan class includes valsartan. Tetrazole ring is present in the structure of this class of compounds. NDEA is created as a byproduct during the synthesis of tetrazole rings. The same way that NDMA is manufactured from DMA, NDEA can be produced from DEA (diethylamine).18,39

 

Figure 6. Formation of NDEA 20

 

The sartan class includes valsartan. This kind of chemical, which contains DEA, may develop from the breakdown of triethylamine (TEA), or it may be present as an impurity in TEA's starting material. The nitrosoiminium ion may directly nitrosate TEA, forming an aldehyde and a secondary amine that then react with nitrous acid to produce a nitrosamine.18

 

FORMATION OF NDMA IN RANITIDINE:

An H2-receptor antagonist (H2RA), ranitidine is frequently prescribed to treat gastroesophageal reflux disease (GERD). Additionally, it is utilised to treat hypersecretory conditions and peptic ulcer disease.10 Ranitidine is licenced to treat heartburn since it lowers the amount of acid that the stomach produces.11 The US Food and Drug Administration (FDA) revealed routine testing has found an impurity in ranitidine in September 2019. N-nitrosodimethylamine (NDMA).12 The researchers discovered a mechanism for the nitrosation of ranitidine in vitro that results in the creation of NDMA under stomach-relevant pH levels.19,39

 

Figure 7. Mechanism of NDMA formation from ranitidine 19

 

METABOLISM OF NDMA:

In the liver of rats, CYP2E1 metabolises NDMA principally, producing a methyldiazonium ion (Fig. 16) that reacts with DNA and largely produces the highly mutagenic N7 and O6 -methylguanine (N7 MG and O6 MG).18

 

Figure 8. Metabolic activation of NDMA formation of the DNA-reactive methyldiazoniumion from NDMA 18

 

METABOLISM OF NDEA:

Humans typically use the enzymes CYP2E1 and CYP2A6 to metabolise NDEA. NDEA causes cancer in numerous species and various organs of laboratory animals, with the liver being the primary target organ. It also causes an increase in mutation in various mouse organs.18 The metabolic activation by CYP2E1 and/or CYP2A6 and DNA-repair abilities for the particular DNA-adducts generated determine NDEA's toxicological effect. Cytochrome p450 enzymes biotransform NDEA to produce an ethyl diazonium ion (mainly CYP2E1). Further interactions between the ion of ethyl diazonium and nucleophilic DNA sites can result in the formation of carcinogenic adducts.22, 39

 

Figure 9. Biotransformation of NDEA and mechanism of DNA-adduct formation 22

 


INTERIM LIMITS FOR NDMA AND NDEA IN ANGIOTENSIN II RECEPTOR BLOCKERS (ARBS)23

Table 1. FDA published interim limit for NDMA and NDEA in sartans11

Drug

Maximumdaily dose(mg/day)

Acceptableintake

NDMA (ng/day)

AcceptableintakeNDMA

(ppm)

AcceptableintakeNDEA

(ng/day)

AcceptableintakeNDEA (ppm)

Valsartan

320

96

0.3

26.5

0.083

Losartan

100

96

0.96

26.5

0.27

Irbesartan

300

96

0.32

26.5

0.088

Azilsartan

80

96

1.2

26.5

0.33

Olmesartan

40

96

2.4

26.5

0.66

Eprosartan

800

96

0.12

26.5

0.033

Candesartan

32

96

3.0

26.5

0.83

Telmisartan

80

96

1.2

26.5

0.33

 

In European Union, EMA gave temporary interim limits for nitrosamine impurity in sartan17

 

Table 2. EMA published limits for NDMA and NDEA in sartans17

drug

Maximumdaily dose(mg/day)

AcceptableintakeNDMA

(ng/day)

AcceptableintakeNDMA(ppm)

Acceptableintake

NDEA (ng/day)

AcceptableintakeNDEA(ppm)

Valsartan

320

96

0.3

26.5

0.082

Losartan

150

96

0.64

26.5

0.177

Olmesartan

40

96

2.4

26.5

0.663

Irbesartan

300

96

0.32

26.5

0.088

candesartan

32

96

3.0

26.5

0.820

 


NITROSAMINE IMPURITY RISK MITIGATION PLAN:11,17

Due to the likelihood or potential for nitrosamines to cause human cancer, FDA and EMA advise assessing the risk of nitrosamine contamination or production in their APIs and medicinal products.

 

Conduct a suitable risk assessment for each drug substance, utilising reputable risk management tools and accounting for suitable risk factors.

 

General quality risk management process:10,11,17

1.       Determine whether APIs, marketed products, and goods with approved or pending applications have nitrosamine impurities. A timely risk assessment should be carried out based on the ranking of the medications.

2.       When there is a chance that nitrosamine impurities may be present, perform confirmatory testing. Due to the physiochemical characteristics of nitrosamines (low molecular weights, some volatility, and significant toxicity), nitrosamine analytical procedures must be extremely selective, good in chromatographic separation, and capable of highly sensitive detection.

3.     Describe the modifications made to APIs and pharmaceutical products to prevent or lessen nitrosamine impurities.

 

Risk management tools:10

Known risk management tools can be used to evaluate and manage risk. The main tools that may be utilised in quality risk include straightforward methods, such as flowcharts, check sheets, process mapping, and cause-and-effect diagrams, which are especially helpful for structuring risk management procedures by gathering and organising data (fish bone diagram).

Fishbone diagram helps to identify and organize possible root cause for the presence of nitrosamine impurity.24-36


 

 

Figure 10. Fishbone diagram of sources of nitrosamine24-36\


Confirmatory testing:10,11,17,37

Manufacturers of APIs and pharmaceutical products should conduct confirmatory testing using appropriate analytical techniques if there is a possibility that nitrosamine impurities may be present.

 

These are the factors that determine whether nitrosamine impurity testing is necessary. Each nation has its own standards for nitrosamine impurity testing.

 

 

Figure 11. Confirmatory testing according to FDA and                 EMA 10,11,17,37

 

API and pharma product producers should look into the underlying cause if a nitrosamine impurity is found in confirmatory testing. Change the procedure in accordance with the results of the investigation and report the adjustments. Manufacturers of API and pharmaceutical products should adopt a system-based strategy to reduce the danger of nitrosamine impurities.

 

Analytical method for detection of impurities:

In order to provide the high-quality products required for human wellbeing, analytical methods are regarded as the foundation of the pharmaceutical industry and research and development labs. Chemical analysis can be divided into two categories: qualitative and quantitative, depending on the manner of operation. Quantitative analysis deals with quantifying required bioactive/impurity components, while qualitative analysis deals with identification. For the qualitative and quantitative measurement of pharmaceuticals, a variety of analytical techniques, such as FT-IR, UV, HPLC, LC-MS/MS, GC-MS/MS with Head space, NMR, LCHRMS, LC-NMR, CE-MS, CE-NMR, SFC-MS, and LC-FT-IR, are frequently employed today.38

 

CONCLUSION:

Numerous medications in the pharmaceutical business are tainted with carcinogenic impurities. These medications have been taken off the market for consumer safety due to their carcinogenic effects. In the last two years, many medications have been pulled from the market after nitrosamine class impurities were discovered in them. The nitrosamine class, which includes NDMA and NDEA, is likely carcinogenic to humans. It is produced by medicines of the sartan class, which have a tetrazole ring in their structure. The -hydroxylation process breaks down NDMA and NDEA into DNA adducts. Antituberculosis medications rifampin and rifapentine produce the nitrosamine impurities MNP and CPNP. Dimethylformamide (DMF), a solvent, was found in valsartan produced by a number of companies, the FDA has been notified. DMF has been labelled as a potential human carcinogen by the WHO. These hazardous impurities are analysed and quantified using a variety of analytical methods.

 

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Received on 23.11.2022       Modified on 20.01.2023

Accepted on 05.03.2023   ©Asian Pharma Press All Right Reserved

Asian J. Pharm. Ana. 2023; 13(4):303-308.

DOI: 10.52711/2231-5675.2023.00049