Potential pitfalls in in vitro antitumor activity testing of free and liposome-entrapped doxorubicin.

This paper addresses several potential problems which may play a critical role in the outcome of in vitro studies designed to investigate the antitumor activity of drugs. These problems were demonstrated to exist in in vitro assays developed for the evaluation of antitumor activity of free and liposome-entrapped doxorubicin (DXR). The stability of DXR-containing liposomes against drug leakage into the culture medium, as well as the chemical stability and extent of adsorption to tissue culture plastics of both free and liposomal DXR during the liposome-tumor cell incubation, were investigated. It is concluded that a full understanding of these processes is required for a reliable interpretation of the experimental results.