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Alpha Zearalanol.svg
Clinical data
Trade namesFrideron, Ralabol, Ralgro, Ralone, Zerano
SynonymsZearanol; α-Zearalanol; Zearalanol; MK-188; P-1496
Routes of
By mouth
Drug classNonsteroidal estrogen
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.043.411 Edit this at Wikidata
Chemical and physical data
Molar mass322.401 g·mol−1
3D model (JSmol)
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Zeranol (INN, USAN, BAN) (brand names Frideron, Ralabol, Ralgro, Ralone, Zerano; developmental code names MK-188, P-1496), or zearanol, also known as α-zearalanol or simply zearalanol, is a synthetic nonsteroidal estrogen of the resorcylic acid lactone group related to mycoestrogens found in fungi in the Fusarium genus and is used mainly as an anabolic agent in veterinary medicine.[1][2][3]

Zeranol is approved for use as a growth promoter in livestock, including beef cattle, under the brand name Ralgro (by Merck Animal Health) in the United States.[4] In Canada, it is approved for use in beef cattle only.[5] Its application is not approved for use in the European Union. However, it is marketed under the brand name Ralone in Spain.[2]

Although zeranol may increase cancer cell proliferation in already existing breast cancer,[6] dietary exposure from the use of zeranol-containing implants in cattle is insignificant by some scholars.[7] Zeranol may be found as a contaminant in fungus-infected crops. It is 3 to 4 times more potent as an estrogen than the related compound zearalenone.[8]

See also[edit]


  1. ^ J. Elks (14 November 2014). The Dictionary of Drugs: Chemical Data: Chemical Data, Structures and Bibliographies. Springer. pp. 350–. ISBN 978-1-4757-2085-3.
  2. ^ a b Index Nominum 2000: International Drug Directory. Taylor & Francis. January 2000. pp. 1105–. ISBN 978-3-88763-075-1.
  3. ^ I.K. Morton; Judith M. Hall (6 December 2012). Concise Dictionary of Pharmacological Agents: Properties and Synonyms. Springer Science & Business Media. pp. 295–. ISBN 978-94-011-4439-1.
  4. ^ Nichols, Wade; Hutcheson, John; Streeter, Marshall; Corrigan, Mark; Nuttelman, Brandon. "Implant Strategies for Finishing Cattle using Revalor® (trenbolone acetate and estradiol), Finaplix® (trenbolone) and/or Ralgro® (zeranol)" (PDF). Merck Animal Health.
  5. ^ Health Canada, Questions and Answers - Hormonal Growth Promoters
  6. ^ Xu, Pingping; Ye, Weiping; Jen, Robert; Lin, Shu-Hong; Kuo, Chieh-Ti; Lin, Young C. (2009-11-01). "Mitogenic activity of zeranol in human breast cancer cells is enhanced by leptin and suppressed by gossypol". Anticancer Research. 29 (11): 4621–4628. ISSN 1791-7530. PMID 20032412.
  7. ^ Lindsay DG (August 1985). "Zeranol--a 'nature-identical' oestrogen?". Food Chem Toxicol. 23 (8): 767–74. PMID 2931335.
  8. ^ Mirocha, CJ; Schauerhamer, B; Christensen, CM; Niku-Paavola, ML; Nummi, M (1979). "Incidence of zearalenol (Fusarium mycotoxin) in animal feed". Applied and Environmental Microbiology. 38 (4): 749–50. PMC 243572. PMID 161492.