Does Nafarelin work?
Yes, in controlled trials; the largest covered 213 women.
The approval rests on randomized double-blind trials against danazol, the standard endometriosis drug of the 1980s. The largest in these citations enrolled 213 women with laparoscopically confirmed endometriosis and judged lesions before and after treatment by repeat laparoscopy. What is missing is modern long-term data; the trials are old, and there is nothing here on use beyond the labeled indications. 12
The endometriosis trial randomized 213 women to nasal nafarelin or oral danazol for a six-month course. Placebo sprays and capsules kept the comparison blind. Doctors did laparoscopy before and after treatment and scored it with the American Fertility Society system. Both drugs reduced the extent of disease by similar amounts. Symptom relief was similar too. The share of women with severe pain fell from about 40% to 5 to 10%. The two drugs differed in side effects. Danazol lowered HDL cholesterol and raised LDL cholesterol, and nafarelin did not. More nafarelin users reported hot flashes and decreased libido. 1
In central precocious puberty, the basis for approval was suppressed LH response and sex hormone levels, with slower advance of bone age. The label describes this. These data come from uncontrolled series in children. A placebo-controlled trial of untreated early puberty would not be ethical. 2
Evidence checklist
- Randomised controlled trial Randomized double-blind versus danazol
- Human study over 100 people 213 women in the largest trial
- More than one research group Trials from the 1980s era sponsors
- Clinical outcomes, not surrogate markers Laparoscopic lesion scoring
- Human safety data beyond case reports Label data and trial adverse events
More on Nafarelin
Citations
- Henzl 1988, N Engl J Med: nasal nafarelin compared with oral danazol for endometriosis pubmed.ncbi.nlm.nih.gov
- Pfizer: Synarel (nafarelin) prescribing information pfizermedical.com
- Pfizer: Synarel adverse reactions pfizermedical.com
Reference information only, not medical advice. Drawn from the Nafarelin article, fact-checked against the cited sources. No dosing anywhere on this site.