Nafarelin
A GnRH-agonist decapeptide delivered as a nasal spray, licensed for endometriosis and central precocious puberty. Like other GnRH agonists it suppresses gonadotropins and sex-steroid output after an initial flare, but its intranasal route gives it a distinct, convenient dosing profile.
01 Overview
Nafarelin is a synthetic GnRH analogue with a substitution that increases potency and resistance to degradation, allowing twice-daily intranasal administration. Continuous receptor stimulation desensitises the pituitary, lowering LH/FSH and therefore oestradiol or testosterone.
It is well studied in endometriosis, where it reduces pelvic pain and lesion size comparably to depot GnRH agonists, and in precocious puberty. Its adverse profile is the familiar hypo-oestrogenic/hypogonadal one, plus nasal irritation specific to the spray route.
02 Mechanism
Continuous GnRH-receptor agonism desensitises the pituitary, suppressing LH/FSH and gonadal sex-steroid production after an initial surge.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Endometriosis | 200–400 mcg/day | Insufflated | One 200 mcg spray each nostril per day (400 mcg/day total). |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Reduced endometriosis painLowers oestrogen, shrinking endometrial implants and easing pelvic pain. | Significant pain/lesion reduction | Clinical | |
| Suppressed precocious pubertyHalts premature pubertal development in children. | Arrest of pubertal signs | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Nasal irritationNasal irritation or rhinitis from the spray. | Mild | Common | Clinical | |
| Hypo-oestrogenic symptomsHot flushes, vaginal dryness, headache and mood change from low oestrogen. | Moderate | Nearly universal | Clinical | |
| Bone density lossReduced bone mineral density with prolonged hypo-oestrogenism. | Moderate | Common with courses >6 months | Clinical |