Abarelix (Plenaxis)
Overview
Abarelix is a synthetic decapeptide that functions as a gonadotropin-releasing hormone (GnRH) receptor antagonist. It competitively blocks pituitary GnRH receptors, producing immediate suppression of luteinizing hormone, follicle-stimulating hormone, and testosterone without the initial surge associated with GnRH agonists. The peptide was developed for treatment of advanced symptomatic prostate cancer in patients who refused surgical castration and were not candidates for GnRH agonist therapy. Its structure incorporates multiple unnatural amino acids to optimize receptor antagonism and pharmacokinetic properties.
Key Research Findings
Abarelix received FDA approval in 2003 but was voluntarily withdrawn from the U.S. market in 2005 due to limited commercial demand and the availability of alternative androgen deprivation therapies. Clinical trials demonstrated rapid testosterone suppression in the majority of patients, but the drug carried a risk of immediate-onset systemic allergic reactions in approximately 1% of patients, necessitating a risk management program. It remains approved in some international markets under restricted prescribing conditions.
Intramuscular injection
FDA Approved
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