title: Miniaturization of powder dissolution measurement and estimation of particle size.
abstract: The objective was to investigate the applicability and limitations of an approach for estimating particle size from powder dissolution measurement using as little as 50 microg of sample in 1 ml of buffer solutions. The powder dissolution profiles of five sparingly-soluble drugs (hydrochlorothiazide, phenazopyridine hydrochloride, 2-naphthoic acid, indomethacin, and dipyridamole) were evaluated with a novel biexponential spherical particle equation and also the Wang-Flanagan spherical particle non-sink equation. The results were compared to particle sizing based on measured specific surface area by the Brunauer-Emmett-Teller (BET) method, and also based on Coulter counting. With the exception of hydrochlorothiazide, the model compounds indicated some agglomeration in the dissolution media. The dry-state specific surface area was larger than expected from either the Coulter method or the powder-dissolution data, especially for phenazopyridine hydrochloride. The particle radii estimated by the powder dissolution method ranged from 10 to 68 microm, with equilibrium solubilities spanning from 5 microg/ml (dipyridamole) to 911 microg/ml (hydrochlorothiazide). Powder dissolution data collected with the miniaturized apparatus can be used to determine particle size, with estimated values agreeing reasonably with those measured by the Coulter counter method.
authors: pION Inc., 5 Constitution Way, Woburn, MA 01801, USA. aavdeef@pion-inc.com
authors: Alex
authors: A
authors: Avdeef
authors: Konstantin
authors: K
authors: Tsinman
authors: Oksana
authors: O
authors: Tsinman
authors: Na
authors: N
authors: Sun
authors: Dmytro
authors: D
authors: Voloboy
mesh_terms: D000465:Algorithms; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008863:Microspheres; D008904:Miniaturization; D008956:Models, Chemical; D010316:Particle Size; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D011208:Powders; D012995:Solubility; D013499:Surface Properties; D013678:Technology, Pharmaceutical; D014466:Ultraviolet Rays; D014783:Viscosity
chemical_list: D004364:Pharmaceutical Preparations; D011208:Powders