The effect of different dose levels of degradable starch microspheres (Spherex®) on the distribution of a cytotoxic drug after regional administration to tumour-bearing rats

Tumour uptake of a radiolabelled anticancer drug, tauromustine ([ 14C]TCNU), was investigated, using two different routes of administration in rats with colon adenocarcinomas implanted in the liver. Intra-arterial administration produced higher concentrations of the drug and/or its metabolites in tumour tissue and lower concentrations in normal tissue compared to intravenous administration. The investigation of co-injection of [ 14C]TCNU intra-arterially with degradable starch microspheres (DSM) indicated that a high dose of DSM (30 mg/kg) resulted in a high concentration of radioactivity in normal liver tissue, and in adjacent organs. This unfavourable pattern was not observed with the low dose of DSM (12.5 mg/kg), which produced a significant increase in tumour uptake. The results demonstrate the efficacy of partial vascular blockade, as elicited by the low dose of DSM. This regime caused [ 14C]TCNU to be preferentially retained in the active peripheral regions of the tumour.