Near-infrared analytical control of pharmaceuticals. A single calibration model from mixed phase to coated tablets.

A new method for analysis of the active compound in a commercial pharmaceutical formulation in different steps of the production cycle, based on near-infrared diffuse reflectance spectroscopy, is proposed. The analysis includes three different steps of the production cycle: granules ready for compression (mixed phase), cores (intermediate) and coated tablets (final product). Satisfactory predictive results for production samples, independently of its origin in the production cycle, require calibration with laboratory-made samples covering the concentration range involved in the manufacturing process, and also production samples from various production batches and different steps, which introduce the variation sources inherent in such a process. A global and sole model was found to determine the active compound during the production cycle, with errors of prediction less than 1.8% in all cases. Tablets can be individually analysed with high accuracy and precision, so a content uniformity analysis may be performed.