*2.1. Materials*

Micronized glyburide (mean particle size 1.66 μm) (GLY) was from Laboratori Guidotti S.p.A. (Pisa, Italy). Glyburide has a pH-dependent solubility; its saturation solubility at 37 ± 0.5 ◦C was determined at pH 1.1 (0.93 ± 0.3 mg/L), pH 6.8 (4.0 ± 0.2mg/L), pH 7.4 (14.9 ± 1.1 mg/L) and pH 8.5 (108.9 ± 10.1 mg/L) (*n* = 3).

Neusilin®US2 (synthetic magnesium alumino-metasilicate) was from Fuji Chemicals, Toyama, Japan), Aeroperl®300 (colloidal silica) from Degussa (Munich, Germany), and Zeopharm®5170 (silicon dioxide) from Huber Engineering Materials (Atlanta, GA, USA). Labrasol® (caprylocaproyl macrogol-8 glycerides) and Transcutol® (diethylene glycol monoethyl ether) were kindly donated by Gattefossé Italia s.r.l. (Milano, Italy). Kollisolv® PYR (2-pyrrolidone, 2-PYR), Kolliphor®HS15 (macrogol 15 hydroxy-stearate), Kollisolv® PEG 400, Kollidon®CL (crospovidone) and Kollidon®VA 64F (copolymer 1vinyl-2-pyrrolidone vinylacetate 60/40) were from BASF Co. Ltd. (Ludwigshafen, Germany). Glycofurol was from Alchymars (Milano, Italy), N,N-dimethylacetamide (DMA) from Carlo Erba (Milano, Italy), Solketal® (1,2-Isopropylidene-*rac*-glycerol), benzyl benzoate and 1,3-butandiole from Merck (Kenilworth, NJ, USA). Avicel®PH102 (microcrystalline cellulose) was from FMC Biopolymer (Philadelphia, PA, USA), Explotab® (sodium starch glycolate) was from Penwest Pharmaceuticals (Patterson, NY, USA), and Ceolus®KG802 (microcrystalline cellulose) from Asahi Kasei (Tokyo, Japan). Mg stearate was from Peter Greven Fett Chemie (Bad Munsterefeil, Germany). Water was obtained from a Milli-Q water purification system (Millipore, MA, USA). All other chemicals and reagents were of analytical grade.
