Liposomes produced by microfluidics and extrusion: A comparison for scale-up purposes.

Successful liposomal formulations in the clinic are severely limited due to poor translational capability of the traditional bench techniques to clinical production settings. The gold standard for liposome bench manufacturing is a multi-step and parameter dependent extrusion method. Moreover, these parameters need re-optimization for clinical production. The microfluidics technique utilizes vigorous mixing of fluids at a nanoliter scale to produce liposomes in batches from milliliters to a couple liters. The fine control of process parameters results in improved reproducibility between batches. It is inherently scalable; however, the characteristics of liposomes produced by microfluidics both in vitro and in vivo have never been compared to those produced using extrusion. In this manuscript, we describe the comparison between the traditional extrusion method to microfluidics, the new paradigm in liposome production and scale-up.

Liposomal formulation of hypoxia activated prodrug for the treatment of ovarian cancer.

In this work, a new sphingomyelin-cholesterol liposomal formulation (CPD100Li) for the delivery of a hypoxia activated prodrug of vinblastine, mon-N-oxide (CPD100), is developed. The optimized liposomal formulation uses an ionophore (A23187) mediated pH-gradient method. Optimized CPD100Li is characterized for size, drug loading, and stability. The in vitro toxicity of CPD100Li is assessed on different aspects of cell proliferation and apoptosis of ES2 ovarian cancer under normoxic and hypoxic conditions. The pharmacokinetics of CPD100Li in mice as well as the influence of A23187 on the retention of CPD100 are assessed. The dose limiting toxicity (DLT) and maximum tolerated dose (MTD) for CPD100Li are evaluated in nude mice. CPD100 is loaded in the liposome at 5.5 mg/mL. The sizes of CPD100Li using DLS, qNano and cryo-TEM techniques are 155.4 ±â€¯4.2 nm, 132 nm, and 112.6 ±â€¯19.8 nm, respectively. There is no difference between the in vitro characterization of CPD100Li with and without ionophore. Freshly prepared CPD100Li with ionophore are stable for 48 h at 4 °C, while the freeze-dried formulation is stable for 3 months under argon at 4 °C. The hypoxic cytotoxicity ratios (HCR) of CPD100 and CPD100Li are 0.16 and 0.11, respectively. CPD100Li under hypoxic conditions has a 9.2-fold lower IC50 value as compared to CPD100Li under normoxic conditions, confirming the hypoxia dependent activation of CPD100. CPD100Li treated ES2 cells show a time dependent enhanced cell death, along with caspase production and an increase in the number of cells in G0/G1 and higher cell arrest. The blood concentration profile of CPD100Li in mice without A23187 has a 12.6-fold lower area under the curve (AUC) and 1.6-fold lower circulation time compared to the CPD100Li with A23187. The DLT for both CPD100 and CPD100Li is 45 mg/kg and the MTD is 40 mg/kg in nude mice. Based on the preliminary data obtained, we clearly show that the presence of ionophore affects the in vivo stability of CPD100. CPD100Li presents a unique opportunity to develop a first-in-kind chemotherapy product based on achieving selective drug activation through the hypoxic physiologic microenvironment of solid tumors.