Toxicity of non-drug-containing liposomes for cultured human cells.

The effects of non-drug-containing liposomes of different compositions and sizes on the proliferation of nine cancer-derived and one normal cultured human cell lines were determined. Stearylamine- and cardiolipin-containing liposomes were toxic (ID50) at 200 microM liposomal lipid concentrations or less, whereas phosphatidylglycerol- and phosphatidylserine-containing liposomes were toxic in the range 130-3000 microM. Phosphatidylcholine or dipalmitoylphosphatidylcholine liposomes were not toxic at 3000-4000 microM. In general, small liposomes were more toxic than large ones. The results indicate that there are wide variations in toxicity of non-drug-containing liposomes for cultured human cells. The potential for nonspecific toxicity due to the liposomes themselves should be carefully considered if human administration of drug-containing liposomes is to be done.