Myocardial effects of mitoxantrone and doxorubicin in the mouse and guinea pig.

Mitoxantrone (DHAQ) was compared to doxorubicin for myocardial effects in the mouse and the guinea pig. Histologically, DHAQ induced a high incidence of focal myocardial damage in mice, similar to that observed with doxorubicin. Functionally, like doxorubicin, DHAQ significantly reduced the rate of contraction and histamine responsiveness of guinea pig right atria in vitro. Additionally, long-term ip administration of either DHAQ or doxorubicin reduced the atrial response to histamine in vitro. These data suggest that DHAQ may have a spectrum of myocardial activity similar to that of doxorubicin.