Paper II
2021 May (Supplementary) (2010 Scheme)

Question

Antibiotics used in cancer chemotherapy

Q53 marksShort Notes

Answer

Antitumour antibiotics are chemotherapeutic agents originally derived from microorganisms.

Examples

  • Doxorubicin (anthracycline)
  • Bleomycin
  • Dactinomycin (Actinomycin D)
  • Mitomycin C

Mechanism of action

  • Doxorubicin: intercalates into DNA, inhibits topoisomerase II, and generates free radicals causing DNA damage
  • Bleomycin: causes DNA strand breakage via free radical generation
  • Dactinomycin: intercalates into DNA, inhibiting RNA polymerase-mediated transcription

Uses

  • Doxorubicin: breast cancer, lymphomas, leukaemias, sarcomas
  • Bleomycin: testicular cancer, Hodgkin’s lymphoma
  • Dactinomycin: Wilms’ tumour, choriocarcinoma

Adverse effects

  • Doxorubicin: cardiotoxicity (dose-limiting, cumulative), myelosuppression, alopecia
  • Bleomycin: pulmonary fibrosis (dose-limiting), minimal myelosuppression

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