Major advances in the treatment of leukaemia and lymphoma in the 1960s and 70s led to the euphoric belief that solid tumours would also yield to cytotoxic chemotherapy. Unfortunately this promise has remained largely unfulfilled. Many reasons are cited for this therapeutic failure, but it is generally accepted that drug resistance, either arising 'de novo' or aquired, is a major factor in this problem. The work detailed in this thesis looks at some possible methods of overcoming so-called pharmacological resistance' i.e. drug resistance based on an inability to deliver enough active drug to it's site of action.