About Doxorubicin Anthracycline antibiotic,Antineoplastic Agent. Mechanism of Action of Doxorubicin This anthracycline antibiotic intercalates the DNA which directly affects the transcription and replication of DNA. It forms a tripartite complex with topoisomerase 2 and DNA.Topomerase2 is an enzyme which is essential for the DNA replication and repair. By these two mechanisms this drug can inhibit the growth of cancer cells. Interactions for Doxorubicin Mercaptopurine: Hepatotoxicity of mercaptopurine enhanced leading to cholestasis. Cyclophosphamide: Exacerbation of cyclophosphamide induced hemorrhagic cystitis. Barbiturates: Increase the plasma clearance of doxorubicin. Digoxin: Decreased serum levels of digoxin. Streptozotocin: Increases toxicity of doxorubicin. Radiation: Radiation induced toxicity to myocardium, mucosa, skin and liver increased.