Cytotoxic effect of different camptothecin formulations on human colon carcinoma in vitro.

Two innovative 20-S-camptothecin (CPT) formulations, previously found suitable to achieve therapeutically relevant CPT concentrations, were assessed for their in vitro cytotoxic potential as compared to an aqueous CPT solution, using the MTT assay. The formulations, cationic CPT-containing liposomes (CPT-Lip), hydroxypropyl-beta-cyclodextrin (HP-beta-CD) complexed CPT (CPT-CD) and a saturated aqueous CPT solution (CPT-Sol), were diluted in culture medium to appropriate CPT concentrations (4.7-300 ng/ml), and incubated with HT-29 and SW-480 human colon carcinoma cell lines. IC50 values were calculated after 48 and 72 h incubation for the HT-29 and SW-480 cell lines, respectively, and were found to be of the same magnitude for all formulations, with only a slight difference (CPT-Sol