Morphine treatment permits doxorubicin hydrochloride to cross blood brain barrier in rat model

Iacopo Sardi, *Giancarlo la Marca, *Maria Grazia Giovannini, °Sabrina Malvagia, °Renzo Guerrini, °Lorenzo Genitori, ^Maura Massimino, Maurizio Aricò

Department of Onco-Hematology, Meyer Children’s Hospital, Florence Italy
*Department of Pharmacology, University of Florence Italy
°Department of Neuroscience, Meyer Children’s Hospital, Florence Italy
^Department of Pediatrics, IRCCS Foundation, National Cancer Institute, Milan, Italy

The blood brain barrier discriminates the access of several molecules into the brain. This hampers the use of some drugs, as doxorubicin, potentially active for treatment of brain tumors. We explored the feasibility of active modification of the blood brain barrier protection, by using morphine pretreatment, to allow doxorubicin accumulation into the brain in an animal model. Rats were pretreated with different doses of intraperitoneal morphine before injection of doxorubicin (12 mg/kg). Quantitative analysis of doxorubicin was performed by mass spectrometry. Acute hearth and kidney damage was analyzed by measuring doxorubicin accumulation, LDH activity and malondialdehyde plasma levels. The concentration of doxorubicin was significantly higher in all brain areas of rats pretreated with morphine than in control tissues (P <0.001). This was evident only at therapeutic morphine dose (10 mg/kg, three times over 24 hours), while lower doses (2.5 and 5 mg/kg) were not associated with doxorubicin accumulation. Pretreatment with morphine did not induce an elevation of LDH activity or of lipid peroxidation compared to controls. Our data suggest that morphine pre-treatment is able to allow doxorubicin penetration inside the brain, by modulating the blood-brain barrier. This is not associated with acute cardiac or renal toxicity. These preliminary results will enable us to generate novel therapeutic approaches to refractory or recurrent brain tumors, and might be useful in other human diseases of the central nervous system in which molecules usually stopped by the blood brain barrier may have a therapeutic impact.