Comparing continuous micromixing and extrusion downsizing for PEGylated nanoliposomes remotely loaded with doxorubicin or the steroid pro-drug methylprednisolone hemisuccinate

Since the FDA approval of the first nanodrug Doxil® in 1995, twenty subsequent liposome and lipid nanoparticle (LNP) based drugs (of which 10 are nanodrugs), were approved by the FDA. The application of such drug-products was considerably boosted by the mRNA-LNP based vaccines used to stop the COVID-19 pandemic. Research on lipid-based vesicles and nanoparticles for drug delivery dates to the 1970s and has culminated in both continuous flow and extrusion-based fabrication processes for current state-of-the-art GMP industrial production of nanoliposomes and lipid nanoparticles. In this study, we compare these two approaches for the preparation of two PEGylated nanoliposome-based drug-products, keeping all other production steps leading to the final drug-product identical. One of these products, generic Doxil®, is remotely and actively loaded with the anthracycline doxorubicin (an amphipathic weak base) driven by a transmembrane ammonium gradient, while the other is methylprednisolone hemisuccinate (an amphipathic weak acid) remotely and actively loaded via a transmembrane acetate gradient. We demonstrate that a microfluidics-based micromixer approach yields equivalent or even better drug-products, especially since the downsizing by microfluidics is not performed above the temperature range of lipid phase transition. The main difference in the physico-chemical features is that size distribution of the microfluidics prepared PEGylated nano liposomes was significantly narrower and morphological analysis by cryo-TEM confirmed higher homogeneity. An additional advantage of the microfluidic approach is that it is a continuous production. Therefore, it enables the direct production of large volumes of high-quality nano-liposomal based drug-products.