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Reproductive & sexual health

Nafarelin

A GnRH agonist that has been an approved nasal-spray medicine for decades — the standing rebuttal to 'nasal peptide means research chemical'.

L5Practice-changingApproved — narrow indicationApprovedHigh confidenceLast reviewed 2026-08-23
Nasal

Also known as: Synarel, nafarelin acetate

Evidence passport

Last reviewed 2026-08-23

Evidence level
L5Practice-changing
Confidence
High confidence
Human efficacy
82/100
Human safety
80/100
Regulatory status
Approved — narrow indication
Development
Approved
Routes
Nasal
Evidence base
Includes human data
Furthest stage
Approved
Source curation
Sources fully curated
Clinical maturity
Long-approved medicine with extensive clinical history

Overview

Human evidence82/100
Preclinical evidence75/100
Human safety evidence80/100

Clinical maturity: Long-approved medicine with extensive clinical history

Routes & formulations

Studied / approved routes

Nasal

The approved product is a metered nasal spray — a demonstration that intranasal delivery is a legitimate regulated route for some peptides, not a marker of the grey market.

Route availability is not evidence of efficacy, and evidence from one route does not transfer to another. The Registry never provides dosing or sourcing information.

Peptide lifecycle

  1. Discovery

  2. Preclinical

  3. Phase I

  4. Phase II

  5. Phase III

  6. Approved

Approved

What it is

A synthetic GnRH agonist that, with continuous use, down-regulates the pituitary-gonadal axis rather than stimulating it.

What people claim

  • Manages central precocious puberty
  • Historical use in endometriosis depending on market

What the evidence actually says

Decades of regulated clinical use support its labelled indications. It is a useful calibration point in this registry: the same molecule class that appears in research-market catalogues also contains serious, long-established medicines.

Human evidence

  • Controlled trials supporting approval and long post-marketing experience.

Preclinical evidence

  • GnRH receptor pharmacology and reproductive endocrinology studies.

Animal and cell findings are Level 1–2 evidence.

Mechanism and pathways

  • Continuous GnRH-receptor agonism desensitises the pituitary, suppressing LH/FSH and gonadal steroids.

Safety and unknowns

  • Effects are dominated by the intended hormone suppression (e.g. hypoestrogenic symptoms).
  • Long-labelled medicine with defined contraindications and monitoring.

Cancer relevance

No concern identified

No established human cancer signal within approved use.

Regulatory status

FDA-approved nasal solution (Synarel) for central precocious puberty; endometriosis labelling has varied by market and label revision. Approval is indication-specific.

Evidence grade

L5Practice-changingHigh confidence

Replicated large randomised trials, pivotal Phase 3 programmes, or a major regulatory decision.

What would change our rating?

  • Not applicable at this evidence tier; routine pharmacovigilance continues.

References and sources

Sources fully curated

Source hierarchy: regulatory documents and trial registries first, peer-reviewed work next, sponsor material flagged as non-independent. We never use supplier or clinic marketing as evidence, and where a verified source has not yet been curated we say so rather than inventing one.

Evidence change history

No recorded changes yet. Baseline position set on 2026-08-23.