An imaging-driven model for liposomal stability and circulation

Area of Science:

• Pharmacology and Drug Delivery
• Biomedical Imaging
• Pharmacokinetics

Background:

• Liposomes are crucial drug delivery vehicles.
• Understanding liposome stability and drug release is vital for optimizing therapeutic efficacy.
• Simultaneous tracking of drug and vehicle is needed to assess delivery dynamics.

Purpose of the Study:

• To develop a method for simultaneous optical and positron emission tomography (PET) labeling of liposome drug and shell.
• To compare the in vivo stability and circulation of long-circulating and temperature-sensitive liposomes.
• To inform a hybrid physiologically based pharmacokinetic model using experimental data.

Main Methods:

• Developed simultaneous optical and PET probes for liposome drug and shell labeling.
• Quantified tracer concentrations in blood, reticuloendothelial system (RES), and tumor interstitium over time.
• Utilized a hybrid physiologically based pharmacokinetic model to analyze liposome behavior.

Main Results:

• Long-circulating liposomes exhibited slower transport to the RES (0.046 h⁻¹) than temperature-sensitive ones (0.19 h⁻¹).
• Drug release rates from circulating long-circulating liposomes (0.003 h⁻¹) were significantly lower than temperature-sensitive ones (0.2 h⁻¹).
• Long-circulating liposomes demonstrated a greater drug area under the curve due to prolonged circulation and slow release.

Conclusions:

• Simultaneous dual-probe labeling and pharmacokinetic modeling provide critical insights into liposome behavior.
• Long-circulating liposomes offer superior stability and drug retention in circulation compared to temperature-sensitive variants.
• Further research will integrate exogenous heat for controlled drug release from temperature-sensitive liposomes.