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

2024, QSAR Flex, Webinar

Applying Expert Knowledge for Nitrosamine Carcinogenicity Assessment

13 Jun 2024

We are excited to introduce a groundbreaking Nitrosation Module for hazard characterization within QSAR Flex. This...

2024, Poster, QSAR Flex

Predicting Nitrosation of Secondary and Tertiary Amines Using Statistical (Q)SAR Models

12 Apr 2024

Since the discovery of the carcinogenic nitrosamine NDMA in pharmaceuticals such as Valsartan in 2018, there...