2.5.3. Powder X-Ray Diffractometry (PXRD)

Powder X-ray diffraction patterns of pure drug and mesoporous silica and clay and of the corresponding liquisolid systems were recorded by a Bruker D8 Advance apparatus (Brucker, Billerica, MA, USA), using a Cu Kα radiation and a graphite monochromator, under the following experimental conditions: 40 mV voltage, 40 mA current, scan rate 0.05◦/s in the 2.5–50◦ 2Θ range, room temperature.

#### 2.5.4. Environmental Scanning Electron Microscopy (ESEM)

The morphological properties of the different liquisolid systems as well as of the final tablet formulations were investigated using a Fei ESEM Quanta 200 Apparatus. Before performing the analyses, samples were sputter-coated with gold-palladium under argon atmosphere, to make them electrically conductive.

#### 2.5.5. Dissolution Test

Dissolution rate experiments were performed according to the dispersed amount method. A sample of each liquisolid system, equivalent to 5 mg drug, was added to 350 mL of pH 7.4 phosphate buffer solution thermostated at 37 ± 0.5 ◦C, in a 400 mL beaker. A three-blade paddle was centrally put in the beaker and rotated at 100 rpm. At given times, aliquots were withdrawn (syringe-filter, pore size 0.45 μm), spectrometrically assayed at 300 nm (UV-Vis 1600 Shimadzu, Tokyo, Japan) for drug content, and replaced with an equal fresh medium volume. A correction fort the cumulative dilution was made. Each test was repeated four times (C.V. < 3.5%). Values of percent of drug dissolved at 10, 30, and 60 min were analyzed by one-way analysis of variance (ANOVA) followed by the Student-Newman-Keuls multiple comparison post-test (Graph Pad Prism 4.0 program, San Diego, CA, USA). Differences were considered statistically significant when *p* < 0.05.

#### *2.6. Tablets Preparation*

Tablets containing 5 mg GLY as liquisolid system, accurately mixed with suitable excipients for direct compression and Mg stearate as a lubricant, were prepared using a Manesty 2 alternative tableting machine. A reference conventional tablet formulation containing the plain drug was also prepared.
