DOXORUBICIN It is an anthracycline antibiotic having anti- tumour activity. Mech of action :- It intercalates between DNA strands and block DNA as well as RNA synthesis. They are also capable of causing breaks in DNA strands by activating topoisomerase-2 and generating quinone type free radicals. As such, they have mutagenic and carcinogenic potential. Maximum action is exeed at S phase, but toxicity is usually exhibited in G2 phase. Adverse effects:- It produces cardiotoxicity as a unique adverse effect. This can manifest either acutely within 2-3 days, causing ECG changes, arrhythmias and hypotension, all of which are reversible; or be delayed--congestive hea failure (related to the total dose administered). CHF is due to cardiomyopathy and may be fatal. Marrow depression, alopecia, stomatitis, vomiting and local tissue damage (on extravasation) are other adverse effects. Urine may be coloured red The anthracycline antibiotics (doxorubicin, etc.) produce cumulative total dose related cardiotoxicity (usually at doses >300 mg/m2). Dexrazoxane is an iron chelating agent when infused i.v. before doxorubicin has been found to reduce risk of such toxicity. However, it may also compromise the anticancer efficacy of doxorubicin. Ref :- kd tripathi;pg num:-867,876