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Nafarelin

Written by The Peptide Record editorialClinical review not yet completedLast reviewed 13 September 2026

Nafarelin (Synarel) is a real, FDA-approved GnRH agonist delivered as a nasal spray rather than an injection — approved in 1990 for endometriosis and later for central precocious puberty, with real trials comparing it directly to oral danazol.

On this page
  1. A nasal-spray GnRH agonist
  2. The pivotal trials
  3. Current status

In brief

Should you care? Relevant if you're comparing GnRH-agonist options for endometriosis or central precocious puberty, especially if avoiding injections matters to you.

The short version

  • Same drug class as leuprolide and goserelin — a GnRH agonist that suppresses estrogen production — but delivered intranasally rather than by injection or implant.
  • A real, danazol-controlled pivotal trial found comparable efficacy with a different side-effect profile.
  • Approved for two distinct indications: endometriosis and central precocious puberty.

A nasal-spray GnRH agonist

Nafarelin is a synthetic gonadotropin-releasing hormone (GnRH) agonist, mechanistically the same class as leuprolide and goserelin already covered on this site — continuous stimulation of the GnRH receptor paradoxically shuts down the pituitary-gonadal axis, suppressing estrogen production. What actually distinguishes nafarelin in practice isn't the mechanism but the route: it's absorbed through the nasal mucosa as a twice-daily spray, rather than requiring an injection or a depot implant.

The pivotal trials

The FDA approved nafarelin (as Synarel) on 13 February 1990 for endometriosis — the first new endometriosis treatment to reach the US market in 14 years — based partly on Henzl et al. (N Engl J Med 1988), a randomized trial of 213 women with laparoscopically confirmed endometriosis comparing nasal nafarelin to oral danazol (800mg/day) for six months — more than 80% of patients in each arm had a reduction in disease extent on repeat laparoscopy, with nafarelin avoiding some of danazol's androgenic side effects. A larger, danazol-controlled confirmatory trial (The Nafarelin European Endometriosis Trial Group, Fertil Steril 1992, PMID 1531464) followed 307 women with 1-year follow-up. A separate indication for central precocious puberty was added based on its ability to suppress premature pubertal hormone production.

Current status

Still marketed by Pfizer as a brand-name product — no FDA-approved generic nafarelin nasal spray was confirmed as of this review, despite the drug's age; treat any claim of a generic version with caution until verified directly. No grey-market or wellness-adjacent presence — a prescription-only hormonal therapy for two specific diagnosed conditions.

References

  1. Henzl MR, Corson SL, Moghissi K, et al., "Administration of Nasal Nafarelin as Compared with Oral Danazol for Endometriosis," N Engl J Med 1988;318(8):485-489, DOI: 10.1056/NEJM198802253180805.
  2. The Nafarelin European Endometriosis Trial Group (NEET), "Nafarelin for endometriosis: a large-scale, danazol-controlled trial of efficacy and safety, with 1-year follow-up," Fertil Steril 1992;57(3):514-522, PMID 1531464.
  3. FDA approval history for Synarel (nafarelin), 13 February 1990.