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

whereas at lower pH values the interior of the particles may provide more favorable
environment for IMC. This could explain the observed differences in IMC release from
the MCM-41 particles at different pH-values. Surprisingly, when common tabletting
excipients were added to the MCM-41 capsule (III), dissolution of IMC was remarkably
improved at pH 5.5 (Figure 8). In comparison, the effect of excipients on bulk IMC was
clear, but still minor. Such a major effect of excipients on the release rate of a drug loaded
into the mesoporous silica has not been reported earlier. Mesoporous silica SBA-15 itself
diminished itraconazole supersaturation, and the phenomenon was partially compensated
by precipitation inhibitors, such as HPMC (Van Speybroeck et al., 2010b). A similar
mechanism may have provided synergy between the excipients and the fast release of IMC
from the ordered mesoporous silica formulations in this study. In this study it was
demonstrated that the improved IMC dissolution from the MCM-41 was maintained after
tabletting (Figure 8).
Figure 8. Release profiles of IMC from encapsulated or tabletted MCM-41 particles (solid
lines, n = 3-4, mean ± SD). Dissolution medium was 0.2 M HCl / 0.2 M KCl (pH 1.2),
phosphate buffer (pH 5.5) or 0.1 M HCl at pH 1.2 which was further raised to pH 6.8
by adding 0.2 M Na3PO4 (pH change) at 37 °C. Bulk IMC is included as a reference
(dashed lines).
The porous properties of silica were further assessed in publications II and III. The
IMC release from MCM-41 (II, III), SBA-15 (II) and Syloid 244 FP EU (III) were
41