---
title: "Nafarelin"
canonical_url: https://peptidelibrary.app/library/nafarelin
description: "Intranasally administered GnRH receptor agonist approved for endometriosis and for central precocious puberty. One of the few peptide drugs delivered routinely by nasal spray."
updated: 2026-11-07
publisher: Peptide Library
notice: "Research and educational use only. Not medical advice."
---

# Nafarelin

Nafarelin is an FDA-approved GnRH receptor agonist. Nafarelin is a GnRH agonist whose D-naphthylalanine substitution at position 6 increases receptor affinity and resistance to degradation, giving sufficient bioavailability for nasal administration. Continuous receptor stimulation downregulates pituitary GnRH receptors after an initial gonadotropin rise, producing reversible suppression of ovarian or testicular steroid production.

Intranasally administered GnRH receptor agonist approved for endometriosis and for central precocious puberty. One of the few peptide drugs delivered routinely by nasal spray.

## Classification

- Type: FDA-approved GnRH receptor agonist
- Mechanism class: GnRH Modulator
- Development stage: Approved product
- Regulatory class: FDA-approved medicine

## Mechanism

Nafarelin is a GnRH agonist whose D-naphthylalanine substitution at position 6 increases receptor affinity and resistance to degradation, giving sufficient bioavailability for nasal administration. Continuous receptor stimulation downregulates pituitary GnRH receptors after an initial gonadotropin rise, producing reversible suppression of ovarian or testicular steroid production.

## Properties

- Molecular formula: C66H83N17O13
- Molecular weight: 1,322.5 g/mol
- CAS number: 76932-56-4
- Studied routes: Intranasal

## Evidence

- Evidence level: FDA Approved
- Highest documented: Regulatory review (FDA label)
- Human trials: 0
- Controlled human trials: 0
- Preclinical sources: 0

Each step shows whether the sources Peptide Library has reviewed include that kind of research. Counts are reviewed sources, not every study ever published. Reviews and programme summaries that describe human use are shown as "reported", not as trials, and registered trials without published results are listed but not counted. A higher step means research has progressed further; it does not mean a compound works better or is safer. Compounds whose evidence has not been reviewed yet show "Not reviewed" instead of a guess.

### Studies

1. SYNAREL (nafarelin acetate) nasal solution — FDA prescribing information (Pfizer), DailyMed. Regulatory label (FDA), human. Population: Children of both sexes with central precocious puberty. Suppression of pituitary-gonadal activity [Source](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=d0aa57cb-d2f4-46d7-af43-7c8b06aa81a6)
2. SYNAREL (nafarelin acetate) nasal solution — FDA prescribing information (Pfizer), DailyMed. Regulatory label (FDA), human. Population: Women aged 18 and over with endometriosis. Pain relief and reduction of endometriotic lesions [Source](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=d0aa57cb-d2f4-46d7-af43-7c8b06aa81a6)

## Safety

Human safety basis: FDA prescribing information

## Regulatory status

Nafarelin is an FDA-approved product for specific labelled indications. Approval does not extend to the research contexts described on this page, and approved products are prescription medicines.

- FDA status: Approved
- Availability: Prescription-Only

## Frequently asked questions

### What is Nafarelin?

Intranasally administered GnRH receptor agonist approved for endometriosis and for central precocious puberty. One of the few peptide drugs delivered routinely by nasal spray.

### How does Nafarelin work?

Nafarelin is a GnRH agonist whose D-naphthylalanine substitution at position 6 increases receptor affinity and resistance to degradation, giving sufficient bioavailability for nasal administration. Continuous receptor stimulation downregulates pituitary GnRH receptors after an initial gonadotropin rise, producing reversible suppression of ovarian or testicular steroid production.

### Is Nafarelin FDA approved?

Yes. Nafarelin is approved by the FDA, and approved products are prescription medicines. Approval is always for specific indications studied in clinical trials, so an approved status does not mean the compound is approved for every use it is discussed for. Research-chemical material sold under the same name is not the approved product.

### What peptides are similar to Nafarelin?

Compounds most often compared with Nafarelin include Leuprolide, Goserelin, Triptorelin and Histrelin. They are grouped by shared mechanism or research area rather than by equivalence, and their regulatory status and evidence base differ.

## References

- [Prospective randomized comparison of ovarian blockade with nafarelin versus leuprolide during ovarian stimulation with recombinant FSH in an ICSI program — J Assist Reprod Genet, 2001](https://pubmed.ncbi.nlm.nih.gov/11804427/)
- [A double-blind randomized study of the treatment of endometriosis with nafarelin or nafarelin plus norethisterone — Gynecol Endocrinol, 1997](https://pubmed.ncbi.nlm.nih.gov/9209899/)
- [\[Nafarelin acetate (Synarel) and thermocoagulation in the treatment of endometriosis\] — Ginekol Pol, 2001](https://pubmed.ncbi.nlm.nih.gov/11526758/)
- [Treatment with nafarelin for endometriosis in young women. Efficacy, safety and lipid metabolism. Niigata Nafarelin Study Group — J Reprod Med, 2000](https://pubmed.ncbi.nlm.nih.gov/10900577/)
- [Retreatment with nafarelin for recurrent endometriosis symptoms: efficacy, safety, and bone mineral density — Fertil Steril, 1997](https://pubmed.ncbi.nlm.nih.gov/9176437/)