Imaging compacted tablet

The in situ compaction study is only possible by using hard ATR crystals, due to the high compressive force used for tablet compaction. Consequently, diamond is the material of choice here, and use of the diamond ATR accessory to obtain ATR-FT-IR images of compacted tablets has been demonstrated previously [35]. ATR-FT-IR images of a model pharmaceutical formulation containing... 

Figure 10.10 Schematic diagram showing the idea of in situ imaging of tablet compaction using a diamond ATR accessory.

The micro-ATR FT-IR imaging approach is readily applicable to study compacted tablets. The contact area of the ATR crystal is circular with a diameter in the region of 100 pm. This area is small enough to easily establish a homogeneous and intimate contact between the ATR crystal and the tablet. To prove this concept, a model tablet, composed of about 3 wt% caffeine in a matrix of starch HPMC of 4 6, was compacted and imaged using the micro-ATR method and the result is shown in Figure 9.10. 

The imaging data were collected over the spectral range of 1200-2400 nm at 10-nm increments using a Sapphire NIR-CI system (Spectral Dimensions, Inc., Olney, MD, USA). The size of FOV was 13 x 10 mm, each pixel sampling an area of approximately 40 x 40 pm. The concentrations of the active ingredients as reported from the manufacturer s label are 37% acetaminophen, 37% aspirin, and 10% caffeine. The remainder of the tablet mass represents the excipient (binder, disintegrant, and lubricant) materials. Pure acetaminophen, aspirin, and caffeine samples are obtained in either tablet form or powder compact and are used to obtain reference spectra of pure components. 

Our group was the first to report imaging with a diamond ATR accessory that provided a field of view of ca. 1 mm2 and the spatial resolution of ca. 15 pm without the use of an infrared microscope [18], The demonstration of the applicability of a diamond ATR accessory for FTIR imaging opened up a range of new opportunities in polymer research, from compaction of tablets [21-23] to studying phase separation in polymer blends subjected to supercritical fluids [24], This imaging approach was successfully utilised for the study of dissolution of tablets in aqueous solutions [25], We have also demonstrated macro... 

Elkhider N, Chan KLA, Kazarian SG. Effect of moisture and pressure on tablet compaction studied with FTIR spectroscopic imaging. J Pharm Sci 2007 96(2) 351-360. 

Figure 10.11 ATR-FT-IR images of a tablet with two components compacted directly on the surface of the diamond crystal in the ATR accessory.

Wray, P. et al. (2008) Compaction of pharmaceutical tablets with different polymer matrices studied by FTIR imaging and X-ray microtoraography. J. Pharm. Sci., 97 (10), 4269-4277. 

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