actinomycin

Actinomycin, most commonly referred to as actinomycin D or dactinomycin, is a chromopeptide antibiotic produced by the bacterium Streptomyces antibioticus. It is one of the oldest anticancer agents and is used in chemotherapy regimens, particularly for pediatric solid tumors.

Mechanism of action: Actinomycin D intercalates into double-stranded DNA at GC-rich regions and inhibits RNA polymerase, thereby blocking transcription and leading to cell death. Its cytotoxic effects are largely restricted to rapidly dividing cells, making it a non-specific but potent antineoplastic agent.

Medical use: In oncology, actinomycin D is used in combination regimens for several pediatric cancers, including Wilms tumor, rhabdomyosarcoma, Ewing sarcoma, and hepatoblastoma. It is occasionally employed in gestational trophoblastic disease. In adults, its use is more limited due to toxicity and the availability of other therapies. It is typically administered intravenously, with dosing guided by body surface area and protocol.

Adverse effects and safety: The drug has a high risk of bone marrow suppression, as well as mucositis, nausea, vomiting, alopecia, and liver or kidney toxicity. Extravasation during administration is a concern. It is teratogenic and generally contraindicated in pregnancy. Cumulative toxicity requires careful monitoring and adherence to protocol-specific dosing.

Chemistry and research use: Actinomycin D belongs to the actinomycin family of planar chromopeptide antibiotics. In laboratory settings, it is used as a transcription inhibitor to study RNA synthesis and gene expression, reflecting its utility both as a medicine and as a molecular biology tool.