Acoustically active perfluorocarbon nanoemulsions as drug delivery carriers for camptothecin: drug release and cytotoxicity against cancer cells.

Camptothecin is a topoisomerase I inhibitor that acts against a broad spectrum of cancers. However, its clinical application is limited by its insolubility, instability, and toxicity. The aim of the present study was to develop acoustically active nanoemulsions for camptothecin encapsulation to circumvent these delivery problems. The nanoemulsions were prepared using liquid perfluorocarbons and coconut oil as the cores of the inner phase. These nanoemulsions were stabilized by phospholipids and/or Pluronic F68 (PF68). The nanoemulsions were prepared at high drug loading of approximately 100% with a mean droplet diameter of 220-420 nm. Camptothecin in these systems showed retarded drug release. Camptothecin in nanoemulsions with a lower oil concentration exhibited cytotoxicity against melanomas and ovarian cancer cells. Confocal laser scanning microscopy confirmed nanoemulsion uptake into cells. Hemolysis caused by the interaction between erythrocytes and the nanoemulsions was investigated. Formulations with phosphatidylethanolamine as the emulsifier showed less hemolysis than those with phosphatidylcholine. Using a 1 MHz ultrasound, an increased release of camptothecin from the system with lower oil concentration could be established, illustrating a drug-targeting effect.