Idarubicin. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in the chemotherapy of cancer.

Idarubicin is a 4-demethoxy-anthracycline analogue of daunorubicin which, when administered intravenously in combination with cytarabine, has therapeutic efficacy superior to that of standard induction and salvage treatment regimens in acute myelogenous leukaemia. Idarubicin alone or in combination regimens has also been effective in limited studies in patients with other acute leukaemias, advanced breast cancer, multiple myeloma and non-Hodgkin's lymphoma. Idarubicin is more lipophilic than its parent drug daunorubicin. It intercalates DNA, induces DNA strand breaks and delays cell cycle progression. Leucopenia is often dose-limiting in patients with solid tumours treated with idarubicin, and most other adverse effects are similar in incidence and severity to those experienced with other anthracycline cytotoxic agents, except for alopecia which appears to occur with a reduced incidence and severity. Cardiotoxic effects have been reported with idarubicin as with other anthracyclines, but animal data and preliminary clinical findings suggest the possibility of reduced cardiotoxicity with idarubicin--a potentially important advantage if confirmed on further study. A maximum cumulative dose of idarubicin beyond which the incidence of cardiotoxicity rapidly increases has not been determined. Thus, intravenous idarubicin is a useful alternative to other anthracyclines (particularly in combination with cytarabine) in the treatment of acute myelogenous leukaemia, and there is some evidence that it is less cardiotoxic than other anthracycline drugs. Further studies are required to establish the use of intravenous idarubicin as a replacement for other intravenous anthracyclines, especially its effect on response duration and survival, and to confirm the evidence of reduced cardiotoxic effects. The role of idarubicin as consolidation and maintenance therapy for various malignancies requires further investigation, as does the potential use of oral idarubicin which is currently under development.