Continuous monitoring of API content, API distribution and crushing strength after tableting via near-infrared chemical imaging

Near-infrared chemical imaging (NIR-CI) with high-speed cameras based on the push-broom acquisition principle is a rapidly-evolving and can be used for a variety of purposes, from classification (and sorting) of products to mapping spatial distribution of materials. The present study examined if NIR-CI is suitable for tablet manufacturing. To that end, the tablets were introduced into the CI system via a flat belt conveyor. A formulation, which consisted of 4 wt.%-6 wt.% caffeine, 5 wt.% crospovidone as a disintegrant, 88 wt.%-90 wt.% lactose as a filler and 1 wt.% magnesium stearate as a lubricator, was tableted at compression forces ranging from 5 kN to 30 kN. The intra- and inter-tablet homogeneity of caffeine and the tablet's hardness were analyzed via NIR‐CI. For the homogeneity evaluation, two methods were applied: standard deviation (SD) and distributional homogeneity index (DHI). The results showed that the SD of caffeine in a single tablet increased with an increase in the caffeine content. This was attributed to natural variations in a binary mixture of caffeine and excipients. Overall, the chosen NIR-CI setup has strong potential to be transferred to the production scale to monitor all tablets in a production stream.

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