QSAR Flex 

Created in collaboration with the US FDA to aid in evaluating the carcinogenic potency of nitrosamines.

NEW! CPCA Prediction Module
Assign a potency category to your N-nitrosamine compounds using the Carcinogenic Potency Categorization Approach (CPCA).

Categorize Compounds according to Regulatory Guidance

Predict acceptable intake (AI) levels according to guidance issued by EMA, US FDA, and Health Canada

Error-Free Score Calculation

  • Remove guesswork & follow the flowchart
  • Correctly count α-Hydrogens
  • Identify deactivating and activating features
  • Flag CPCA exception cases

Advanced Surrogate Search

Search for surrogates with robust data

Batch Mode Execution

Evaluate multiple compounds in a single query

The chemical structure of the NDSRI in question usually differs significantly in size and complexity when compared with nitrosamines that have experimental carcinogenicity data. To compare the query chemical with the most relevant analogs, QSAR Flex can perform an analog search based on structural features in the immediate vicinity of the N-Nitrosamine moiety. 


Where carcinogenicity study data for an impurity are of lesser quality as described in ICH M7, a surrogate compound with carcinogenicity data may be used to derive an acceptable intake but should be scientifically justified. Read-across can be used for justification purposes.

Experimental Data

The robustness of the carcinogenicity data must be considered when selecting appropriate analogs.

Molecular Property Prediction

Properties such as molecular weight, lipophilicity, and water solubility should be considered when selecting and justifying surrogate compounds.

Related Research

2022, Collaboration, Poster, QSAR Flex

Assessing Carcinogenic Potency of Untested Nitrosamines

21 Mar 2022

The carcinogenic potency of untested nitrosamines were identified with the help of surrogates....

2022, Poster, QSAR Flex

A New Structural Similarity Method to Identify Surrogate Compounds for Assessing the Carcinogenicity of Nitrosamine Impurities

21 Mar 2022

This study sought to develop a computational local similarity method to more objectively and efficiently calculate...