Figure 7.

(Top a,b): Schematic representation of (a): Intermolecular hydrogen bonding in DP. Two molecules are linked together by two hydrogen bonds, linking the benzimidazole terminals through N8H and O1 atoms (b): Hydrogen bonding and dipole dipole interaction between DP and PVPK30 (bottom c) FTIR spectra of droperidol (DP), crystalline (C), amorphous(A), PVPK30 solid dispersion (SD) and physical mixture (PM) at 1680 cm⁻¹ 1677 cm⁻¹ (O21), 1704 cm⁻¹ (C=O, (O1) in dimers) and 1718 cm⁻¹ (non-hydrogen bonded C=O, (O1)). The 1704 cm⁻¹ correspond to O1 in dimer structure. * The peak disappearing in the solid dispersions indicating the lack of the dimers in the solid dispersion.