[Fundamental studies on locally injected methotrexate bound to activated carbon particles (MTX-CH)]

We developed a new dosage formulation of methotrexate bound to activated carbon particles (MTX-CH). In this study, subcutaneous injection of MTX-CH was examined for its long-acting effect at the injection sites, anti-tumor effect and acute toxicity in mice. MTX-CH- or MTX aqueous solution (MTX-SOL)- was injected locally into tumors growing on the back of BALB/c mice at a dosage of 30 mg/kg as methotrexate (MTX). (1) The MTX concentration at the injection sites remained higher in mice with MTX-CH than that with MTX-SOL. (2) A marked effect on the control of tumor growth by MTX-CH was noted after repeated injections throughout the observation period. These results suggest that MTX-CH is superior to MTX-SOL due to longer-acting effects at the administration site and have a better control of tumor growth than MTX aqueous solution (MTX-SOL).