Key takeaways
- Nafarelin is FDA approved under the brand name Synarel.
- It treats central precocious puberty (CPP) in children and is also indicated for endometriosis.
- Thirteen clinical trials have studied nafarelin or related GnRH agonist protocols.
- Reported side effects are dominated by ovarian hyperstimulation syndrome, with far fewer reports of dyspnoea, ascites, and gastrointestinal symptoms.
What nafarelin is
Nafarelin is a synthetic peptide hormone marketed as Synarel. Several registered trials describe it functioning as a GnRH agonist, a class of hormone therapy used to modulate the body's reproductive hormone signaling. Its molecular formula is C66H83N17O13.
What nafarelin is approved for
Synarel is indicated for central precocious puberty, a condition where children show premature sexual development before age 8 in girls or age 9 in boys, along with accelerated bone age or a poor predicted adult height. Diagnosis typically involves confirming pubertal hormone levels along with pelvic ultrasound findings such as an enlarged uterus and ovaries. The label also covers endometriosis as a separate indication. No boxed warning is present on the label.
What the evidence shows
Across clinical trial registries, nafarelin and related GnRH agonist regimens appear in 13 registered studies. One Phase 3 trial, still recruiting, is evaluating GnRH agonist support during the luteal phase after GnRH agonist triggering in IVF and ICSI cycles. A separate completed trial examined a protocol designed to reduce the number of injections and blood draws required during in vitro fertilization.
Reported side effects
Adverse event reports linked to nafarelin are led by ovarian hyperstimulation syndrome, with 48 reports, reflecting its use in fertility related protocols. Respiratory and fluid related reports follow, including dyspnoea (19 reports) and ascites (18 reports). Smaller numbers of reports describe general symptom aggravation, diarrhoea, headache, and nausea, each in the range of 13 reports, alongside 13 reports flagged as off label use. These figures represent submitted reports, not confirmed incidence or proven causation.