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Pharmacology · Antitumour antibiotics

Dactinomycin !

Actinomycin D: wedges into DNA and stops RNA synthesis. Used for childhood solid tumours such as Wilms tumour and for gestational trophoblastic disease.

Updated 2026-11-01

  • Class: Antitumour antibiotics
  • Target: DNA (guanine–cytosine steps); blocks RNA polymerase
  • ATC code: L01DA01
  • WHO Model List of Essential Medicines

Also called: actinomycin D

The crystal shows actinomycin D bound to a short DNA duplex; the drug is stored in the entry as two short peptide chains with its ring system, not as a small ligand.

Target in 3D: DNA (guanine–cytosine steps); blocks RNA polymerase. PDB structure 1MNV (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Dactinomycin's planar phenoxazone ring slips between adjacent guanine–cytosine base pairs, while its two peptide loops lie in the minor groove. The stable drug–DNA complex blocks RNA polymerase, so transcription stops; at higher levels DNA synthesis is also inhibited.

  1. The ring intercalates between G–C base pairs
  2. Peptide loops lock into the minor groove
  3. RNA polymerase cannot move: transcription stops

Pharmacokinetics

Absorption
Intravenous, or by isolated regional perfusion of a limb or organ.
Distribution
Concentrates in nucleated cells; does not cross the blood–brain barrier.

Indications

  • Metastatic nonseminomatous testicular cancer, in combination. Testicular cancer →
  • Wilms tumour, rhabdomyosarcoma and Ewing sarcoma, in multi-phase combination regimens.
  • Gestational trophoblastic neoplasia, alone or in combination.
  • Regional perfusion for locally recurrent solid tumours.

Adverse effects

Common

  • Nausea and vomiting
  • Mouth sores (mucositis) and difficulty swallowing
  • Myelosuppression
  • Rash, hair loss and fatigue

Contraindications

  • None listed in the US label; live-virus vaccines are not recommended before or during treatment

Key interactions

Radiotherapy
Dactinomycin increases radiation toxicity and can reactivate skin and mucosal reactions in previously irradiated areas.
Live-virus vaccines
Not recommended before or during treatment.

What is monitored

  • Blood counts before each cycle
  • Liver tests, weight, liver size and ascites (veno-occlusive disease)
  • Creatinine and electrolytes

Administration and safety

  • Vesicant and corrosive: given intravenously with extreme care to avoid extravasation.
  • Extravasation: stop, restart in another vein and apply ice intermittently.
  • In-line filters with a cellulose ester membrane are not used.
  • Doses are very small (micrograms): calculations are double-checked.
  • Hazardous drug: prepared and given following hazardous-drug handling procedures (impervious gloves, no skin contact) and disposed of as cytotoxic waste.

Nursing care

  • Independent double check of drug, patient, route and cycle before giving it (high-alert medicine).
  • Watch the infusion site closely and ask about burning or stinging.
  • Weigh daily and look for abdominal swelling, jaundice or a tender liver (veno-occlusive disease).
  • Mouth care and antiemetics; skin care over irradiated areas.
  • Teaching: report fever, chills, sore throat, bleeding or bruising at once.

Pregnancy and breastfeeding

Can cause fetal harm (teratogenic in animals); effective contraception is used during treatment.

Test yourself

Think of the answer, then tap the question to see it.

What is the main mechanism of dactinomycin?

It intercalates at guanine–cytosine pairs and blocks RNA polymerase, stopping transcription.

Which serious liver complication is linked to dactinomycin, and who is most at risk?

Hepatic veno-occlusive disease; children younger than 4 and patients also receiving radiotherapy.

Which two paediatric tumours are classically treated with dactinomycin?

Wilms tumour and rhabdomyosarcoma (also Ewing sarcoma).

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: DailyMed - DACTINOMYCIN injection, powder, lyophilized, for solution (DailyMed (U.S. National Library of Medicine), 2024); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 70 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).

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