Nonclinical Testing Evaluation of Liposomes as Drug Delivery Systems

Area of Science:

• Pharmacology
• Drug Delivery Systems
• Toxicology

Background:

• Liposomes are widely used as drug delivery systems in marketed and investigational drugs.
• These systems are often described as "non-toxic" materials.

Purpose of the Study:

• To examine safety testing considerations for liposomal drug delivery systems.
• To review nonclinical packages supporting the safe clinical use and marketing of liposomal drugs.
• To evaluate liposome-only study findings.

Main Methods:

• Review of nonclinical safety data for liposomal drug products.
• Analysis of studies supporting clinical entry, focusing on oncology indications.
• Examination of liposome-only toxicity findings.

Main Results:

• Most experience involves established drugs formulated in liposomes with known excipients.
• A minimal study package for clinical entry includes in vivo pharmacology, pharmacokinetics, and repeat-dose toxicity.
• Liposomes are not "non-toxic"; observed toxicities often relate to macrophage processing with no known human safety consequence.
• Hypersensitivity reactions in some PEGylated liposome forms have clinical relevance.

Conclusions:

• Liposomal drug delivery systems require comprehensive safety evaluations beyond the assumption of non-toxicity.
• Proposed minimal study package aids in supporting clinical entry for liposomal drugs.
• Understanding liposome-specific toxicities, like hypersensitivity, is crucial for clinical application.