Study on in vitro stability of polymerized liposomes

Area of Science:

• Lipid-based drug delivery systems
• Polymerized liposomes
• Phospholipid chemistry

Background:

• Liposomes are widely used for drug delivery but can be unstable in physiological conditions.
• Conventional phospholipids are susceptible to degradation and leakage in acidic environments and in the presence of bile salts.
• Polymerization of phospholipids offers a potential strategy to enhance liposome stability.

Purpose of the Study:

• To evaluate the stability of liposomes composed of polymerized 1,2-bis-(octadeca-2,4-dienoyl)-sn-glycero-3-phosphocholine (DENPC) under various conditions.
• To compare the stability of polymerized DENPC-liposomes with non-polymerized DENPC-liposomes and conventional phospholipid liposomes.
• To investigate the effect of carboxymethyl chitin (CM-chitin) on the stability of polymerized DENPC-liposomes.

Main Methods:

• Liposomes were prepared using polymerized and non-polymerized DENPC, as well as conventional phospholipids.
• Liposome stability was assessed by monitoring the leakage of entrapped 3H-sucrose.
• Stability was tested under acidic conditions (pH 3.3 and 2) and in the presence of bile salts (20 mM).
• The effect of CM-chitin on liposome stability was also evaluated.

Main Results:

• Polymerized DENPC-liposomes exhibited significantly higher stability against acidic pH and bile salts compared to non-polymerized DENPC-liposomes and conventional liposomes.
• The presence of CM-chitin further enhanced the stability of the polymerized DENPC-liposomes.
• Non-polymerized liposomes showed increased leakage under tested conditions.

Conclusions:

• Polymerized DENPC-liposomes represent a more robust formulation for drug delivery applications.
• These liposomes demonstrate superior resistance to degradation and leakage in challenging environments like the gastrointestinal tract.
• CM-chitin can be utilized as an additive to further improve the stability of polymerized liposomes.