Watch out for suppliers who cannot give a clear account of where their critical intermediate material, such as 6-APA, originates. Be wary of missing information about batch-specific testing of nitrosamines and other impurities unless specifically asked. Recent FDA warning letters or listings in an import alert are a red flag. Pricing below the average market price with no justification should also be viewed with suspicion. Lastly, unwillingness to disclose facility inspection history is itself a red flag.
More Info: https://www.panchit.com/blogs/61228/Why-Paracetamol-Metformin-and-Amoxicillin-Are-Still-the-Riskiest-APIs