Spectroscopic Imaging of Compacted Pharmaceutical Tablets

Chemical images of compacted pharmaceutical tablets were obtained in situ using a miniature compaction cell and a diamond Attenuated Total Reflection (ATR) accessory. Combining this in situ ATR approach with FTIR imaging yielded chemical images based on the spatial distribution of the absorbance of the spectral bands for corresponding excipients in the tablets. The chemical specificity of this approach enables enhanced visualization of compacted tablets. Model excipients and drug used in these experiments were avicel, hydroxypropylmethylcellulose (HPMC), lactose, magnesium stearate and paracetamol. Univariate and multivariate analysis were employed to analyse spectroscopic datasets. It has been shown that in situ spectroscopic imaging provides information about the distribution and particle size of each component within the tablet despite the similarity in colour and chemical structure of some of the components. It was also possible to elucidate density distribution of major components within the tablets. This approach can assist in the understanding of tablet compaction in the pharmaceutical industry and ultimately help to optimize this blending process.