The drug loading, cytotoxicty and tumor vascular targeting characteristics of magnetite in magnetic drug targeting.

Chemotherapy is a popular treatment approach against cancer but significant uptake of drugs by normal tissues is still a major limitation. Magnetic drug targeting (MDT) has been used to improve localized drug delivery to interstitial tumor targets. MDT is now being developed to improve drug delivery to tumor vessels. We thus seek to understand the role of magnetite (MAG-C) in drug loading, influence on cytotoxicity and vascular targeting characteristics. The inclusion of MAG-C at lower concentrations (0.5 mg/ml) in cationic liposomes did not alter the efficiency of loading etoposide, but at higher concentrations (2.5 mg/ml) incorporation decreased from 80+/-3.4% to 44+/-4.26%. MAG-C reduced the incorporation of dacarbazine. The incorporation was significantly lower compared to liposomal etoposide, both in the presence and absence of MAG-C. The incorporation efficiency of vinblastine sulfate in cationic liposomes was similar for low and relatively high MAG-C content; values for incorporation were 21+/-0.11 and 23+/-2, respectively. Polyethylene-glycol improved the efficiency of loading chemotherapeutic agents regardless of drug type. Additionally, cytotoxicity and tumor vascular targeting characteristics of liposome therapeutics were not influenced by MAG-C. The components used to prepare magnetic liposomes for MDT should be optimized for maximum therapeutic benefit.