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Investigation into Intermolecular Interactions and Phase Behavior of Binary and Ternary Amorphous Solid Dispersions of Ketoconazole
journal contribution
posted on 2020-02-20, 15:36 authored by Kanika Sarpal, Cole W. Tower, Eric J. MunsonConventionally, amorphous
solid dispersions (ASDs) have been formulated
as a binary matrix, but in recent years a new class of ASDs has emerged,
where generally a second polymer is also added to the formulation.
Having the presence of a second polymer necessitates a comprehensive
solid-state characterization to study the intermolecular interactions
and phase behavior on a molecular level. With this goal in mind, ketoconazole
(KET) was selected as a model drug, and hydroxypropyl methyl cellulose
(HPMC) and poly(acrylic acid) (PAA) were chosen as polymeric carriers.
The binary and ternary ASDs were characterized by differential scanning
calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy,
solid-state nuclear magnetic resonance (SSNMR) spectroscopy, and powder
X-ray diffraction (PXRD). The binary KET:HPMC dispersions lacked any
specific interactions, whereas binary KET:PAA dispersions and ternary
KET:PAA:HPMC dispersions showed evidence for ionic and hydrogen bonding
interactions. The 13C SSNMR deconvolution study established
a comparison for molecular interactions between the binary KET:PAA
and ternary KET:PAA:HPMC dispersions, with the binary KET:PAA system
showing higher prevalence of ionic and hydrogen bonds than the ternary
KET:PAA:HPMC system. Moreover, individual binary and ternary ASDs
were found to be homogeneous on a nanometric level, implying the presence
of a second polymer did not impact the phase homogeneity. In addition,
a stronger interaction in binary KET:PAA and ternary KET:HPMC:PAA
systems translated to better physical stability at different storage
conditions. Through this case study it is recommended that a comprehensive
investigation is needed to study the impact of using two polymers
in ASD formulations in terms underlying intermolecular interactions
and physical stability.