Haematotoxicity of doxorubicin and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) and of their association in rats

Doxorubicin is an anthracycline widely used in the treatment of leukaemias, lymphomas and solid tumors. Doxorubicin cannot pass into the cerebrospinal fluid. Nitrosoureas are known to be lipophilic and to be able to penetrate the blood-brain barrier. CCNU is a nitrosourea used to treat Hodgkin's disease, brain tumors and other solid tumors. The authors have previously reported on the nephrotoxicity and hepatotoxicity of these drugs; the present paper reports their findings on haematotoxicity in female Wistar rats. In one group 40 rats received 10 mg/kg doxorubicin. In a second group 40 rats received 20 mg/kg CCNU, and a further 40 rats received 50 mg/kg CCNU. In a third group 60 rats received the association doxorubicin 10 mg/kg plus CCNU 20 mg/kg. Blood counts were performed on days 4, 8, 15, 21 and 28 after treatment. Leucopenia and severe thrombocytopenia were noted after doxorubicin administration. A biphasic decrease in the leucocyte count was observed after CCNU treatment. More severe alterations were observed when doxorubicin and CCNU were combined. Very few data on haematological abnormalities following treatment of human patients have been published. Similarities can be seen between the haematological side-effects noted in rats and those occurring in humans treated with these cytotoxic drugs. Female Wistar rats seemed to be a good model to evaluate the haematological tolerance of anthracycline, nitrosoureas or of their association. If multiple courses of these drugs have to be administered, the evolution of haematological alterations must be known: the decrease phase of blood cells is followed by a rebound phase. The drug should be avoided during this phase of granulocyte activation.