Toxicity of intraperitoneally administered antitumour drugs in athymic rats

The toxicity of eight anticancer drugs given intraperitoneally to athymic rats was investigated to define the maximum tolerable doses (MTD). Drugs were given once weekly. Toxicity was assessed as percentage loss of body weight (LBW%) or percentage toxic death rate (TDR%) during the first week after drug administration. LBW% and TDR% were significantly correlated, r = 0.58 p less than 0.00001. From the regression equation for the relationship between LBW% and TDR%, 10 percent TDR (LD10), usually regarded as equivalent to MTD in animals, was found to correspond to 14 percent LBW. From the individual regression equations for LBW% and dose for each of six drugs, MTDs were calculated to be as follows; doxorubicin 7 mg/kg, cyclophosphamide 100 mg/kg, mitomycin C 1.8 mg/kg, cisplatin 8 mg/kg, vindesine 0.8 mg/kg and vincristine 0.9 mg/kg. LD10 was found to be 40 mg/kg for both carmustine (BCNU) and etoposide.