Detection of counterfeit and substandard tablets using non-invasive NIR and chemometrics - A conceptual framework for a big screening system.

A detailed step-by-step procedure for revealing counterfeit and substandard tablets is presented. Non-invasive NIR measurements are used for data collection. The entire complex multi-layer object as the "packaging -coating-core" system requires special treatment at all stages of model development and validation. The influence of each layer is studied. A procedure that covers data collection, construction of the model, as well as special internal and external validation is advocated here. A special set of objects called 'nearest of kin' (NoK) collection, which consists of generic medications nearest to the target objects, assists in reliable assessment of the model specificity. The whole procedure summarizes the results obtained for over a thousand different dosage forms of tablets. Two real-world examples of genuine and counterfeit medicines are considered. The first example presents uncoated tablets with high concentration of active ingredient and fairly simple set excipients. Its NoK collection consists of six different manufacturers. The second example presents coated tablets with low concentration of active ingredient and rather complex set of excipients. Its NoK collection is presented by seven different manufacturers.