N-Nitroso Donepezil EP Impurity A: Chemical Structure, Characterization, and Analytical Significance

chemiceamarketing

Oct 19

8 min read

Nitrosamine impurities have become an important area of investigation in pharmaceutical development, analytical research, and quality control. Their identification and monitoring are particularly relevant because certain nitrosamine compounds have demonstrated carcinogenic potential, making their presence in pharmaceutical substances a significant quality and regulatory consideration.

N-Nitroso Donepezil EP Impurity A is a specific nitrosamine-related impurity associated with Donepezil. It is also known as N-Nitroso Desbenzyl Donepezil. Understanding its chemical identity, structural characteristics, and analytical properties is important for laboratories involved in pharmaceutical impurity profiling and nitrosamine analysis.

Donepezil is a centrally acting medication used in the management of Alzheimer's disease. During pharmaceutical development and manufacturing, impurities may arise from starting materials, synthetic intermediates, chemical transformations, or other process-related factors. Nitrosamine-related impurities require particular attention because their assessment involves sensitive analytical techniques and appropriate reference materials.

The study of N-Nitroso Donepezil EP Impurity A supports research into the identification and characterization of related impurities. Pharmaceutical analytical laboratories can use suitable reference standards to support method development, chromatographic evaluation, and impurity profiling.

Chemical Identity and Molecular Characteristics

Understanding the chemical identity of an impurity is an essential first step in analytical characterization. Reliable identification helps distinguish structurally related compounds and supports the selection of suitable analytical procedures.

The reported chemical information for N-Nitroso Donepezil EP Impurity A is presented below.

Product Name: N-Nitroso Donepezil EP Impurity A

Synonym: N-Nitroso Desbenzyl Donepezil

CAS Number: 3069884-01-8

Molecular Formula: C17H22N2O4

Molecular Weight: 318.37 g/mol

IUPAC Name: 5,6-Dimethoxy-2-[(1-nitrosopiperidin-4-yl)methyl]-2,3-dihydro-1H-inden-1-one

These identifiers provide a foundation for chemical database searches, reference-standard selection, and analytical investigation.

The molecular formula indicates the presence of carbon, hydrogen, nitrogen, and oxygen atoms. The two nitrogen atoms are particularly relevant to its classification as an N-nitroso compound. However, molecular formula alone cannot establish the complete molecular structure or confirm the identity of an unknown sample. Structural identification requires appropriate analytical evidence.

Understanding the Chemical Structure of N-Nitroso Donepezil EP Impurity A

The chemical structure of N-Nitroso Donepezil EP Impurity A contains two important structural regions: a substituted indanone-based portion and a nitrosated piperidine ring.

The indanone portion contains two methoxy substituents at the 5- and 6-positions. This structural arrangement is connected through a methylene linkage to a piperidine ring.

The piperidine nitrogen carries the N-nitroso functionality, which is a defining structural feature of this compound.

The presence of the N-nitroso group distinguishes this compound from non-nitrosated Donepezil-related impurities. It also makes the compound relevant to investigations involving pharmaceutical nitrosamine impurities.

Another important structural distinction concerns its relationship to Desbenzyl Donepezil. The compound is identified as N-Nitroso Desbenzyl Donepezil because its structure corresponds to the nitrosated desbenzyl-related Donepezil framework rather than the complete Donepezil structure.

Accurate structural differentiation is important when selecting analytical reference materials. Compounds with similar pharmaceutical names may have substantially different molecular structures, molecular weights, and chromatographic characteristics.

Relationship Between Donepezil and Nitrosamine Impurities

Donepezil is an acetylcholinesterase inhibitor used in the treatment of symptoms associated with Alzheimer's disease. Its pharmaceutical development and manufacturing involve chemical synthesis, purification, formulation, and quality assessment.

Like other pharmaceutical substances, Donepezil-related materials may require investigation for process-related impurities, degradation products, and potentially relevant nitrosamine impurities.

Nitrosamines are a class of compounds characterized by the presence of an N–N=O functional arrangement. Their formation can involve the reaction of susceptible nitrogen-containing compounds with nitrosating species under suitable chemical conditions.

However, the formation pathway of an individual nitrosamine depends on its molecular structure, precursor chemistry, reaction environment, and processing conditions.

For N-Nitroso Donepezil EP Impurity A, the presence of the nitrosated piperidine nitrogen provides the structural basis for its classification as an N-nitrosamine. Its specific formation mechanism should be established through appropriate chemical investigation rather than assumed from its structural classification.

This distinction is important for pharmaceutical researchers because identifying a possible impurity and establishing how it forms are two different scientific activities.

Analytical Characterization of N-Nitroso Donepezil EP Impurity A

Analytical characterization plays a central role in identifying pharmaceutical impurities and evaluating their presence in drug substances or related samples.

For N-Nitroso Donepezil EP Impurity A, a combination of analytical techniques may be considered depending on the purpose of the investigation, sample characteristics, and required sensitivity.

1. High-Performance Liquid Chromatography (HPLC)

High-performance liquid chromatography is widely used in pharmaceutical impurity profiling because it helps separate individual components within complex sample mixtures.

For Donepezil-related impurity investigations, an appropriately developed HPLC method can support the separation of the target impurity from the active pharmaceutical ingredient and other related compounds.

Method development generally involves evaluating:

Suitable stationary-phase chemistry.
Mobile-phase composition and pH.
Flow rate and column temperature.
Detection wavelength or compatible detection technique.
Resolution between the target impurity and related components.

A reference standard can help establish the retention characteristics of the target compound under defined chromatographic conditions.

However, retention time alone is insufficient to confirm chemical identity. Additional analytical evidence should be considered.

2. Liquid Chromatography–Mass Spectrometry (LC-MS)

LC-MS is particularly useful for investigating pharmaceutical impurities because it combines chromatographic separation with mass-based detection.

The reported molecular weight of N-Nitroso Donepezil EP Impurity A is approximately 318.37 g/mol. Its molecular formula, C17H22N2O4, provides a basis for calculating expected mass-to-charge characteristics during method development.

LC-MS can support:

Investigation of the target compound in pharmaceutical samples.
Evaluation of molecular-ion information.
Differentiation of related compounds based on mass characteristics.
Confirmation of chromatographic peak assignments when supported by suitable evidence.

High-resolution mass spectrometry may provide additional information about elemental composition through accurate-mass measurements.

The selection of ionization conditions, precursor ions, and fragmentation parameters should be experimentally established for the target analyte.

3. Nuclear Magnetic Resonance (NMR) Spectroscopy

NMR spectroscopy provides valuable information about molecular structure and the chemical environment of different hydrogen and carbon atoms.

For a compound such as N-Nitroso Donepezil EP Impurity A, proton NMR and carbon NMR can help investigate the structural arrangement of the substituted indanone and piperidine portions.

NMR characterization may support the evaluation of:

Aromatic proton environments.
Methoxy group signals.
Aliphatic proton environments.
Structural changes associated with nitrogen substitution.
Overall consistency with the proposed molecular structure.

NMR interpretation should be performed using actual experimental spectra rather than relying solely on predicted chemical shifts.

4. High-Resolution Mass Spectrometry (HRMS)

HRMS is useful when accurate mass measurements are required to support molecular formula assessment.

For nitrosamine-related impurities, accurate-mass data can complement chromatographic and spectroscopic findings.

The combination of HRMS, LC-MS, and NMR provides complementary analytical information. The suitability of each technique depends on the investigation's objective and the available instrumentation.

Importance of Reference Standards in Impurity Profiling

Reference standards are essential tools in pharmaceutical analytical laboratories. They provide characterized materials against which unknown samples can be evaluated.

For N-Nitroso Donepezil EP Impurity A, an appropriate reference standard can support several analytical activities.

Method development: Reference material can help establish chromatographic separation conditions and evaluate the analytical response of the target compound.

Peak identification: Comparing sample behaviour with a suitable reference standard can support the assignment of chromatographic peaks.

Method verification and validation: Reference materials may be incorporated into studies evaluating specificity, accuracy, precision, linearity, and other relevant performance characteristics.

Impurity profiling: Reference standards can help researchers investigate the presence of specific impurities in pharmaceutical substances and related materials.

Research and development: Characterized impurity materials support investigations into pharmaceutical synthesis, degradation behaviour, and analytical methodology.

The suitability of a reference standard depends on its identity, assigned purity, characterization documentation, storage conditions, and intended analytical application.

A certificate of analysis (COA) should be reviewed before using any reference material in laboratory investigations.

Nitrosamine Impurities and Pharmaceutical Quality Considerations

Nitrosamine impurities are an important consideration in pharmaceutical quality risk management. Regulatory agencies have established guidance and recommendations for identifying, assessing, and controlling relevant nitrosamine impurities in medicinal products.

The US Food and Drug Administration (FDA) provides guidance on nitrosamine impurity assessment, including analytical testing approaches and acceptable intake considerations for specified compounds.

Analytical methods used for nitrosamine investigations may include sensitive techniques such as LC-MS/MS and GC-MS/MS, depending on the chemical characteristics of the target analyte and the sample matrix.

For quantitative analysis, laboratories should evaluate relevant method performance characteristics, including:

Specificity and selectivity.
Accuracy and recovery.
Repeatability and intermediate precision.
Linearity and analytical range.
Limit of detection and limit of quantitation.
Sample and solution stability.

Importantly, acceptable intake limits are compound-specific. The limits established for one nitrosamine should not automatically be applied to another structurally different compound.

Likewise, identifying a compound as a nitrosamine does not independently establish its toxicological classification or an acceptable intake limit. Such assessments require appropriate compound-specific evidence and regulatory evaluation.

Role of N-Nitroso Donepezil EP Impurity A in Pharmaceutical Research

The availability of a suitable reference material for N-Nitroso Donepezil EP Impurity A can contribute to several areas of pharmaceutical research.

Analytical laboratories may use this compound to investigate chromatographic behaviour, evaluate mass-spectrometric response, and support the identification of related impurities.

Pharmaceutical manufacturers and contract research organizations may also require characterized impurity materials when developing analytical procedures or investigating potential impurities associated with drug substances.

For research involving Donepezil-related compounds, distinguishing N-Nitroso Donepezil EP Impurity A from ordinary Donepezil EP Impurity A is particularly important.

Despite their similar names, these are chemically different substances. Ordinary Donepezil EP Impurity A is a desbenzyl-related compound, whereas N-Nitroso Donepezil EP Impurity A contains an additional nitroso functionality and has a different molecular formula and molecular weight.

Selecting the correct reference material is therefore essential for reliable analytical interpretation.

N-Nitroso Donepezil EP Impurity A Reference Standard from Chemicea

Chemicea Pharmaceuticals Pvt. Ltd. is a chemistry-driven pharmaceutical company and contract research organization specializing in pharmaceutical impurity reference standards and custom synthesis.

The company offers reference materials covering different pharmaceutical impurity categories, including process impurities, degradation products, nitrosamines, metabolites, glucuronides, and stable-isotope-labelled compounds.

Chemicea supports pharmaceutical research and analytical development through its impurity reference-standard portfolio and custom synthesis capabilities.

For laboratories investigating Donepezil-related nitrosamine impurities, Chemicea offers N-Nitroso Donepezil EP Impurity A (CAT. No. CP-D2023).

The product information includes:

Product Name: N-Nitroso Donepezil EP Impurity A

CAT. No.: CP-D2023

CAS Number: 3069884-01-8

Molecular Formula: C17H22N2O4

Molecular Weight: 318.37 g/mol

Synonym: N-Nitroso Desbenzyl Donepezil

According to the available Chemicea certificate of analysis, the reported analytical characterization includes HPLC purity, LC-MS mass confirmation, and proton NMR identification. The displayed batch COA reports an HPLC purity result of 98.72%.

Chemicea's pharmaceutical reference standards and custom synthesis services support research laboratories, pharmaceutical manufacturers, and analytical organizations working on impurity identification and characterization.

Frequently Asked Questions (FAQs)

1. What is N-Nitroso Donepezil EP Impurity A?

N-Nitroso Donepezil EP Impurity A is a nitrosamine-related impurity associated with Donepezil. It is also known as N-Nitroso Desbenzyl Donepezil and contains an N-nitroso functional group attached to a piperidine nitrogen.

2. What is the molecular formula of N-Nitroso Donepezil EP Impurity A?

Its reported molecular formula is C17H22N2O4, with a molecular weight of approximately 318.37 g/mol.

3. What is the CAS number of N-Nitroso Donepezil EP Impurity A?

The reported CAS Registry Number is 3069884-01-8. Researchers should verify the identifier against the supplier's product documentation before analytical use.

4. Which analytical techniques are useful for characterizing this impurity?

HPLC, LC-MS, HRMS, and NMR spectroscopy can provide complementary information for investigating its chromatographic behaviour, molecular mass, and chemical structure. The appropriate combination depends on the analytical objective.

5. Why are reference standards important for nitrosamine impurity analysis?

Reference standards help laboratories investigate target impurity identity, develop analytical methods, compare chromatographic responses, and support appropriate analytical validation activities.

6. Is N-Nitroso Donepezil EP Impurity A the same as Donepezil EP Impurity A?

No. They are chemically distinct compounds. N-Nitroso Donepezil EP Impurity A contains an N-nitroso functionality and has the molecular formula C17H22N2O4, whereas ordinary Donepezil EP Impurity A has a different chemical structure and molecular formula.

7. Where can researchers source N-Nitroso Donepezil EP Impurity A?

Researchers can explore the N-Nitroso Donepezil EP Impurity A reference standard offered by Chemicea Pharmaceuticals through its dedicated product page. Product documentation and availability can be confirmed directly with the company.

Conclusion

N-Nitroso Donepezil EP Impurity A is an important compound for research involving Donepezil-related nitrosamine impurities. Its chemical structure, molecular characteristics, and analytical behaviour make it relevant to pharmaceutical impurity profiling and analytical method development.

Techniques such as HPLC, LC-MS, HRMS, and NMR spectroscopy provide complementary approaches for investigating its identity and characterization. The use of appropriate reference standards further supports reliable analytical assessment and the differentiation of structurally related impurities.

For pharmaceutical researchers, QC laboratories, and analytical development teams, access to properly characterized impurity reference materials is an important part of maintaining reliable analytical practices.

Chemicea Pharmaceuticals supports these research requirements through its pharmaceutical impurity reference standards, nitrosamine reference materials, and custom synthesis capabilities, helping pharmaceutical organizations address their analytical research and impurity characterization needs.