Application of near-infrared spectroscopy in the pharmaceutical solid dosage form

Near-infrared (NIR) spectroscopy, one of the most rapidly growing methodologies in pharmaceutical analysis, has been used to analyze the pharmaceutical solid dosage form. The objective of this study was to examine the information that can be gathered from NIR spectroscopy and demonstrate the potential utility of the technique as an alternative to current methods of tablet performance testing. The tablet formulation included active drug (acetaminophen or theophylline), binder (hydroxyethylcellulose), filler (lactose, calcium sulfate, dibasic calcium phosphate dihydrate, or microcrystalline cellulose), and lubricant (magnesium stearate). The compression forces were varied from 5 to 25 kN. A Foss/NIRSystems scanning near-infrared spectrometer was used to measure the diffuse reflectance from the tablet surface. Each tablet was scanned on opposite sides to reduce the effects of positioning. First derivative and multiplicative scatter correction data treatments were explored. A calibration for compression force, independent of the filler, was developed. In addition, the spectra were able to distinguish among the fillers used. A comparison of these spectra with data collected earlier suggests that the technique could differentiate among drugs as well. Near-infrared diffuse reflection spectroscopy, when properly calibrated, can determine the compression force used to prepare a tablet. This measurement may be independent of the different active drugs or fillers used in the tablet formulations.