Mesoporous silica- and silicon-based materials ... - Helda - Helsinki.fi

evaluated at pH 1.2 in publication II and at pH 5.5 in publication III, and the results are
combined in Figure 9 for better comparison. The release was the slowest from the particles
with the smallest pore diameter, MCM-41, and became faster with increasing pore
diameter (Figures 6 and 9). In addition, the smaller the particle size is, the faster the drug
molecule diffuses out of the particle (Qu et al., 2006a; Cauda et al., 2008). Thus, the
smaller particle size of Syloid 244 FP EU (2.5-3.7 µm), as compared to that of the studied
ordered mesoporous silicas (< 125 µm), favored the faster IMC release from the particles
(Fig. 9).
Figure 9. Effect of the pore properties on the IMC release from mesoporous silica at different
pH values (n = 3-4, mean ± SD). Dissolution medium was 0.2 M HCl / 0.2 M KCl (pH
1.2) or phosphate buffer (pH 5.5) at 37°C.
5.6 Permeation (IV)
Furosemide, a poorly soluble and permeable drug, was loaded into TCPSi particles and the
drug absorption was evaluated in Caco-2 permeability studies. Drug permeability was
improved from the TCPSi particles as compared to pre-dissolved solutions at all the pHvalues
studied. The improved furosemide dissolution from the TCPSi particles provided
higher local concentrations of the drug for absorption through the cell monolayers than
from the plain furosemide solutions, especially at pH 5.5 where the poor solubility of
42