Toxicological Issues Faced after Liposomes Administration

Previous studies highlighted the anaphylactoid nature of liposome reactions, pointing to activation of the complement (C) system as probably the underlying cause [13]. It was also established earlier that multilamellarity, large size, and the presence of very high amounts of cholesterol in the bilayer membrane are likely one of the main cause of C activation and anaphylactoid reactions. More recently, the causal role in C activation of acidic phosphate groups on polyethyleneglycol conjugated (PEGylated) phosphatidylethanolamine (PE) has been demonstrated [14-16].