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GnRH analogue

Nafarelin

Brand names: Synarel

A gonadotrophin-releasing hormone agonist given intranasally, used for endometriosis and for pituitary down-regulation in assisted reproduction.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

Continuous GnRH receptor stimulation desensitises the pituitary after an initial flare, suppressing gonadotrophin release and lowering ovarian oestrogen production.

Prescribing in practice

  • Prolonged oestrogen suppression reduces bone mineral density, so limit treatment duration and consider add-back therapy and bone protection where appropriate.
  • An initial hormonal flare can transiently worsen symptoms at the start of treatment.
  • Exclude pregnancy before starting, advise non-hormonal contraception, and avoid in undiagnosed vaginal bleeding.

Monitoring

Monitor symptom response, menopausal side effects and, with prolonged or repeated courses, bone mineral density.

Counselling the patient

  • Menopause-like effects such as hot flushes, mood change and vaginal dryness are common.
  • Use a non-hormonal contraceptive method and avoid becoming pregnant during treatment.
  • Do not use a nasal decongestant immediately around dosing without advice, and report any worsening of symptoms early in treatment.

Evidence & guidelines

GnRH agonists such as nafarelin are recognised in NICE endometriosis guidance (NG73) as hormonal options for managing endometriosis-associated pain.

Reference: NICE NG73; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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