Evaluation of liposomes coated with a pH responsive polymer

Area of Science:

• Pharmaceutical Sciences
• Materials Science

Background:

• Liposomes are versatile drug delivery systems.
• pH-responsive polymers offer potential for targeted drug release.
• Eudragit S100 is a pH-responsive polymer suitable for gastrointestinal applications.

Purpose of the Study:

• To coat liposomes with Eudragit S100 for enhanced gastrointestinal targeting.
• To evaluate the pH-responsive drug release characteristics of the coated liposomes.
• To assess the stability and integrity of the polymer coating under simulated physiological conditions.

Main Methods:

• Cationic liposomes were coated with anionic Eudragit S100 via simple mixing.
• Polymer coating evolution was analyzed using zeta potential and laser diffraction.
• Light and cryo scanning electron microscopy confirmed polymer-liposome association.
• In vitro drug release studies were conducted at pH 1.4, 6.3, and 7.8.

Main Results:

• The Eudragit S100 coating significantly reduced drug release at acidic pH (1.4) and mildly acidic pH (6.3).
• Drug release at pH 7.8 was comparable to uncoated liposomes, demonstrating pH-responsive behavior.
• Microscopy confirmed successful association of the polymer with the liposomes.
• The coating integrity was compromised by bile salts, highlighting the need for complex media evaluation.

Conclusions:

• Eudragit S100 coated liposomes exhibit promising pH-responsive release profiles for lower gastrointestinal targeting.
• The formulation demonstrates controlled drug release in simulated stomach and small intestine environments.
• Further studies incorporating complex media like bile salts are crucial for comprehensive formulation assessment.