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Oncology · FDA Approved

Abarelix (Plenaxis)

FDA-approved

How to ask your doctor
Written by Peptide Association Editorial TeamLast reviewed Editorial policy

01 · Overview

Abarelix is a synthetic decapeptide that functions as a gonadotropin-releasing hormone (GnRH) receptor antagonist. Because it blocks pituitary GnRH receptors directly, it lowers luteinizing hormone, follicle-stimulating hormone, and testosterone without the initial surge seen with GnRH agonists (PMID 11711355). Its US product (Plenaxis) was approved for advanced prostate cancer, but because of allergic reactions its use was restricted to a subgroup of patients (PMID 23577417).

The product has been discontinued in the US. Its structure incorporates multiple unnatural amino acids to optimize receptor antagonism and pharmacokinetic properties.

02 · Research summary & key findings

Abarelix was the first GnRH antagonist approved by the FDA, in 2003, and was withdrawn from the US market in 2005 amid concerns that included hypersensitivity reactions (PMID 24775720). In a phase 3 trial of 269 men, no abarelix patients had a testosterone surge versus 82% on leuprolide, and 78% were castrate by day 8, with comparable castration maintenance through day 85 (PMID 11711355). In 81 men with symptomatic advanced disease, none required orchiectomy over 168 days of treatment (PMID 14624912). Phase 3 trials found a higher incidence of immediate-onset systemic allergic reactions with abarelix than with comparator therapies, which restricted its use (PMID 17155895, PMID 23577417).

03 · Regulatory status

Abarelix (Plenaxis) has received FDA approval and is available for clinical use under appropriate medical supervision. Consult a qualified healthcare provider for prescribing information.

Abarelix (Plenaxis) is an FDA-approved medicine prescribed for the conditions on its label. It is not part of our intake, so we do not propose protocols for it. If you think it may be relevant to you, talk to your own doctor. How to ask your doctor.

04 · Administration routes

  • Intramuscular injection

References

  1. [1]A phase 3, multicenter, open-label, randomized study of abarelix versus leuprolide acetate in men with prostate cancer Urology, 2001. PMID 11711355
  2. [2]An open-label study of abarelix in men with symptomatic prostate cancer at risk of treatment with LHRH agonists Urology, 2003. PMID 14624912
  3. [3]Abarelix for injectable suspension: first-in-class gonadotropin-releasing hormone antagonist for prostate cancer Future Oncol, 2006. PMID 17155895
  4. [4]Five years' clinical use of GnRH antagonists: evaluation of safety and allergic potential Reprod Biomed Online, 2005. PMID 23577417
  5. [5]Utility of LHRH antagonists for advanced prostate cancer Can J Urol, 2014. PMID 24775720

Primary literature

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Disclaimer: This information is provided for educational and research purposes only. It is not intended as medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting any peptide therapy. The Peptide Association does not endorse or recommend any specific treatment protocol. See our editorial policy for how this content is produced and reviewed. Clinicians: join the network.