title: A near-infrared spectroscopic investigation of relative density and crushing strength in four-component compacts.
abstract: Near-infrared spectroscopy (NIRS) is commonly employed for the analysis of chemical and physical attributes of intact pharmaceutical compacts. Specifically, NIRS has proven useful in the nondestructive measurement of tablet hardness or crushing strength. Near-infrared (NIR) reflectance and transmittance spectra were acquired for 174 13-mm compacts, which were produced according to a four-constituent mixture design (29 points) composed of anhydrous theophylline, lactose monohydrate, microcrystalline cellulose, and soluble starch. Six compacts were produced for each design point by compacting at multiple pressures. Physical testing and regression analyses were used to model the effect of variation in relative density (and crushing strength) on NIR spectra. Chemometric analyses demonstrated that the overall spectral variance was strongly influenced by anhydrous theophylline as a result of the experimental design and the component's spectroscopic signature. The calibration for crushing strength was more linear than the relative density model, although accuracy was poorer in comparison to the density model due to imprecision of the reference measurements. Based on the consideration of reflectance and transmittance measurements, a revised rationalization for NIR sensitivity to compact hardness is presented.
authors.affiliation: Duquesne University Graduate School of Pharmaceutical Sciences, 410A Mellon Hall, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, USA.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Short
authors.forename: Robert P
authors.initials: RP
authors.lastname: Cogdill
authors.forename: Peter L D
authors.initials: PL
authors.lastname: Wildfong
authors.forename: James K
authors.initials: JK
authors.lastname: Drennen
authors.forename: Carl A
authors.initials: CA
authors.lastname: Anderson
mesh_terms: D002138:Calibration; D002482:Cellulose / Q000737:chemistry; D004339:Drug Compounding; D006245:Hardness Tests; D007785:Lactose / Q000737:chemistry; D016018:Least-Squares Analysis; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013213:Starch / Q000737:chemistry; D013607:Tablets / Q000737:chemistry*; D013806:Theophylline / Q000737:chemistry
chemical_list: D013607:Tablets; D002482:Cellulose; D013213:Starch; D013806:Theophylline; D007785:Lactose; C109691:microcrystalline cellulose