Supersaturated drug delivery system (
SDDS) enables the solubility and sustained membrane transport of poorly water-soluble drugs.
SDDS provides higher
drug concentration in the dispersed phase and equilibrium in the continuous phase, which corresponds to amorphous solubility of the
drug.
Rifaximin (RFX) is a nonabsorbable BCS class IV
drug approved for the treatment of
irritable bowel syndrome and effective against Helicobacter pylori. RFX shows slow crystallization and precipitation in an acidic pH of 1.2-2, leading to obliteration of its activity in the gastrointestinal tract. The objective of the present study is to inhibit the precipitation of RFX, involving screening of
polymers at different concentrations, using an in-house developed microarray plate method and solubility studies which set forth
hydroxypropyl methylcellulose (HPMC) E15,
Soluplus, and
polyvinyl alcohol to be effective precipitation inhibitors (PIs).
Drug-
polymer precipitates (PPTS) are examined for surface morphology by scanning electron microscopy, solid-phase transformation by hot stage microscopy, the nature of PPTS by polarized light microscopy, and
drug-
polymer interactions by Fourier transform infrared and nuclear magnetic resonance spectroscopy. Besides, the unfathomed molecular mechanism of
drug-
polymer interplay is discerned at the air-water interface using sum-frequency generation spectroscopy to correlate the interfacial hydrogen bonding properties in bulk water. Surprisingly, all studies disseminate HPMC E15 and
Soluplus as effective PIs of RFX.