title: Acoustic assessment of mean grain size in pharmaceutical compacts.
abstract: An ultrasonic non-destructive technique for the microstructure length-scale characterization of solid dosage pharmaceutical tablets is presented. The technique is based on the relationship between the attenuation of longitudinal ultrasonic elastic waves and the size of micro-structural features in the tablet material. In the reported experiments, the ultrasonic attenuation in microcrystalline cellulose (MCC)-lactose monohydrate (LMH) blended pharmaceutical compacts is measured by means of two pitch-catch experiments. The frequency dependent attenuation coefficient for the MCC-LMH compacts is then related to the mean grain diameter for each compact. For verification purposes, the mean grain diameter of the compacts was also established using micro-scale X-ray computerized tomography (MicroXCT). The mean grain diameters established by both routines agree well, and support the efficacy of the ultrasonic attenuation technique. The microstructure of a pharmaceutical compact (i.e., grain sizes and micro-feature size distribution) has been shown to have a profound effect on its mechanical properties, namely hardness, porosity, and mass density distribution, and in turn, can critically impact the dissolution profile and structural integrity of a compact. The ultrasonic technique presented provides a non-destructive and rapid method for determining the mean grain diameter size for powder compacts, thus providing a more timely and cost-effective method, compared to traditional techniques, of characterizing a compact's internal microstructure.
authors.affiliation: Dept. of Chemical and Biomolecular Engineering, Clarkson University, Potsdam, NY 13699-5725, USA.
authors.forename: Carson J
authors.initials: CJ
authors.lastname: Smith
authors.forename: James D
authors.initials: JD
authors.lastname: Stephens
authors.forename: Bruno C
authors.initials: BC
authors.lastname: Hancock
authors.forename: Armin Saeedi
authors.initials: AS
authors.lastname: Vahdat
authors.forename: Cetin
authors.initials: C
authors.lastname: Cetinkaya
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D005079:Excipients / Q000737:chemistry; D006244:Hardness; D007785:Lactose / Q000737:chemistry*; D010316:Particle Size; D016062:Porosity; D011208:Powders; D012995:Solubility; D013607:Tablets; D014465:Ultrasonics; D055114:X-Ray Microtomography / Q000379:methods*
chemical_list: D005079:Excipients; D011208:Powders; D013607:Tablets; D002482:Cellulose; D007785:Lactose; C109691:microcrystalline cellulose