Antagonism of doxorubicin cardiotoxicity by carnitine is specific of the L-diasteroisomer.

The therapeutic use of Doxorubicin in the treatment of human solid tumors is restricted because of its cardiotoxicity. It has been demonstrated that D,L-Carnitine reduces or suppresses some of the cardiotoxic effects produced by the antibiotic. The results of this study, carried out on rat heart Langendorff preparation show that the decrease in heart rate, coronary flow, and contractile force, occurring after Doxorubicin infusion, was antagonized by the laevo-diasteroisomer; the dextroform was totally inactive. On the contrary, both forms increased phospholipid concentration in the myocardium. This would suggest that the reparatory effect of L-Carnitine against Doxorubicin cardiotoxicity is linked to the natural role played by this substance in metabolic processes.