A novel hybrid microparticulate system composed of poly(lactic-co-glycolic) acid (PLGA) nanoparticles and submicron medium-chain
triglyceride (MCT) droplets was fabricated to overcome the pH-dependent solubility and precipitation challenges associated with a model poorly water-soluble weak base, cinnarizine (CIN). Molecular
CIN was confined within both the lipid and polymer phase of PLGA-lipid hybrid (PLH) and PLGA-lipid-mannitol hybrid (PLMH) particles, which offered significant biopharmaceutical advantages in
comparison to the unformulated drug, submicron MCT droplets and PLGA nanoparticles. This was highlighted by a substantial reduction in the pH-induced precipitation during in
vitro gastrointestinal two-step dissolution studies. A >2.5-fold solubilisation enhancement was observed for the composite particles during simulated intestinal conditions, compared to pure
CIN. Furthermore, the drug solubilisation capacity during in vitro intestinal digesting conditions was ~2–2.5 times greater for PLMH particles compared to the precursor emulsion
droplets and PLGA nanoparticles. The observations from this study indicate that a synergy exists between the degradation products of PLGA nanoparticles and lipid droplets, whereby the dual-phase
release and dissolution mechanism of the hybrid particles aids in prolonging pH-provoked precipitation. Subsequently, the ability for PLGA polymers and oligomers to act as polymeric precipitation
inhibitors has been highlighted for the first time.
