Optimizing the Filtration of Liposomes Using Sterilizing-Grade Filters

Area of Science:

• Pharmaceutical Technology
• Biotechnology
• Materials Science

Background:

• Liposomes are vital injectable drug delivery systems.
• Sterilizing filtration (0.2 µm) of liposomes is challenging due to their size and properties.
• Existing filter validation studies show increased risk of blockage and bacterial penetration with liposomes.

Purpose of the Study:

• To investigate the sterilizing filtration of liposomes.
• To understand the impact of filtration parameters and liposome characteristics on filtration efficiency.
• To identify strategies for optimizing liposome filtration for injectable formulations.

Main Methods:

• Lipoid S100 liposomes were prepared using microfluidization.
• Filtration studies were conducted using polyethersulfone sterilizing-grade filters.
• Effects of prefiltration, serial filtration, differential pressure, inlet pressure, liposome size, and size distribution were examined.

Main Results:

• Decreasing liposome size from 179.0 to 127.3 nm increased volumetric throughput over 40-fold.
• Increasing differential pressure significantly improved volumetric throughput (e.g., 18-fold increase from 0.7 to 4.1 bar).
• Higher differential pressure enhanced liposome transmission through sterilizing-grade membranes.

Conclusions:

• Optimization of filtration processes and formulation characteristics is key to improving liposome sterilizing filtration.
• Adjusting liposome size and filtration parameters like differential pressure can overcome filtration challenges.
• This research provides critical insights for selecting and validating sterilizing filters for liposomal drug products.