Development and characterization of a liposome preparation by a pH-gradient method

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery Systems
• Liposome Technology

Background:

• Liposomes are versatile drug delivery vehicles.
• Efficient drug loading into liposomes remains a challenge.
• Orciiprenaline sulphate is a model drug used in this study.

Purpose of the Study:

• To establish and evaluate a pH-gradient method for loading orciprenaline sulphate into liposomes.
• To develop and assess a scalable eight-step process for liposome preparation.
• To investigate the stability of drug-loaded liposomes.

Main Methods:

• Utilized a pH gradient across liposome bilayers for drug loading.
• Employed diafiltration to remove excess external drug.
• Performed lyophilization with lactose as a cryoprotectant.
• Analyzed drug concentration using High-Performance Liquid Chromatography (HPLC).
• Determined liposome vesicle size and polydispersity using laser light scattering.

Main Results:

• Achieved high encapsulation efficiencies of 80-85% for orciprenaline sulphate.
• Successfully scaled up the liposome preparation process.
• Demonstrated the effectiveness of diafiltration for drug removal.
• Observed an increase in vesicle size and decrease in encapsulation efficiency over five months at 2-8°C.

Conclusions:

• The pH-gradient method is highly effective for encapsulating orciprenaline sulphate into liposomes.
• Liposome stability is affected by storage conditions, leading to vesicle fusion and drug leakage.
• Further research is needed to optimize liposome formulations for long-term stability.