Peptide LexiconAll compounds

Gonadorelin: A Hormone That Was Twice an Approved US Medicine, and Is Now Sold as a Research Chemical

Gonadorelin is synthetic GnRH, the hormone that tells the pituitary to release LH and FSH. It had two US approvals, both discontinued. What it is, what it does, and what the evidence covers.

Formerly FDA-approvedBoth US products discontinued

Caroline S · Published 2026-09-08

Length

Decapeptide (10 amino acids)

Sequence

Identical to natural human gonadotropin-releasing hormone

Origin

A synthetic copy of a hormone made in the hypothalamus

Last reviewed

2026-09-08

What is it good for?

It is sold today mainly alongside testosterone replacement, on the argument that it keeps the body's own testicular signalling active. That is not what either of its US approvals was for: those were a diagnostic test of pituitary function and a fertility treatment for a specific hormonal disorder.

Illustration: A clear glass beaker with a faint deep green liquid on a white lab bench under soft light.
Illustration

What it is

Gonadorelin is synthetic gonadotropin-releasing hormone — GnRH — a chain of ten amino acids identical to the hormone the hypothalamus makes.

Its role in the body is to be the first signal in a chain. The hypothalamus releases GnRH in pulses; the pituitary responds by secreting luteinizing hormone and follicle-stimulating hormone; those act on the testes or the ovaries. Everything downstream of that — testosterone, oestrogen, ovulation, sperm production — depends on the pulse pattern at the top.

This is not a novel compound. It is a copy of something the body has used continuously for as long as there have been vertebrates.

It was an approved medicine, twice

This is unusual in this library, and it is checkable in one query. Drugs@FDA holds two applications:

Product Application Sponsor Strengths Status
FACTREL NDA 018123 Hikma 0.1 mg, 0.2 mg, 0.5 mg per vial Discontinued
LUTREPULSE KIT NDA 019687 Ferring 0.8 mg, 3.2 mg per vial Discontinued

Lutrepulse was originally approved on 1989-10-10. Every product under both applications is now marked Discontinued (openFDA Drugs@FDA query, 2026-09-08).

The two were for quite different purposes. Factrel was a diagnostic: give the hormone, measure the pituitary's response, and you learn whether the gland works. Lutrepulse was a fertility treatment: a kit with a pump that delivered pulses to induce ovulation in women with hypothalamic amenorrhoea.

Neither was a testosterone-support product, which is what gonadorelin is mostly sold as today.

Pulses, not amounts

The most important thing about this hormone is that its effect reverses with the delivery pattern.

Delivered in pulses, GnRH stimulates: the pituitary releases LH and FSH. Delivered continuously, it desensitises the receptor and the same hormones fall. That is not a side effect or a quirk of dosing — it is the basis of an entire drug class. GnRH agonists are used to suppress the reproductive axis in prostate cancer and endometriosis precisely because sustained exposure shuts it down.

Lutrepulse was sold with a pump for that reason. A quantity of this hormone, on its own, does not tell you which direction it will push the system. The approved drug built on the continuous side of that rule is triptorelin, a long-acting GnRH analogue, which the labels use to switch sex hormones off.

An enormous literature that is mostly about something else

PubMed indexes 43,221 records for gonadorelin, 2,456 of them randomized controlled trials (E-utilities, 2026-09-08). That is far more than anything else in this library, and it is the most misleading number here.

Nearly all of it belongs to reproductive medicine and oncology, where GnRH analogues are used to control the axis — usually to suppress it. The literature is real and it is large. It is not evidence about a vial of gonadorelin used to keep testicular signalling active during testosterone therapy, which is a different question that has not been asked at anything like that scale.

A compound's name appearing in tens of thousands of papers is not the same as evidence for the thing being sold. Gonadorelin is the sharpest case of that distinction in this library.

Where it stands

There is no marketed US product. The hormone itself is thoroughly characterised — its structure, its receptor, and its dual behaviour are not in doubt. What is missing is trial evidence for the modern use, and there is no approved product whose labelling could supply a reference point.

Related entries in this library: kisspeptin sits one step upstream — it is the signal that drives GnRH release in the first place. Sermorelin is the closest parallel elsewhere in this library: another hormone fragment that held a US approval and lost it. For a hormone that bypasses the pituitary and acts on the testes directly, see the entry on human chorionic gonadotropin.

Last checked

2026-09-08. The Drugs@FDA records for NDA 018123 (FACTREL) and NDA 019687 (LUTREPULSE KIT) were read through the openFDA API on that date, as were the PubMed counts.

What the research shows

Triggers release of LH and FSH from the pituitary

This is the hormone's defined physiological action; it is why it was approved as a diagnostic agent

Induces ovulation in hypothalamic amenorrhoea when pulsed by pump

The approved indication of Lutrepulse, a US product from 1989 to its discontinuation

Preserves testicular function during testosterone therapy

The use it is currently sold for; not an approved indication of either US product and not what either was studied for

Bars show how much of the evidence is in humans, not how well anything works.

Where it stands

United States

No marketed product. Two applications exist in Drugs@FDA and both are discontinued: FACTREL (NDA 018123, Hikma) in 0.1, 0.2 and 0.5 mg vials, and LUTREPULSE KIT (NDA 019687, Ferring, originally approved 1989-10-10) in 0.8 and 3.2 mg vials.

Evidence base

Very large, and mostly not about the compound as sold: PubMed indexes 43,221 gonadorelin records, 2,456 of them randomized controlled trials (2026-09-08).

Sold as

A lyophilized research vial, usually marketed with testosterone-replacement products.

Frequently asked questions

What is gonadorelin?

It is synthetic gonadotropin-releasing hormone — a chain of ten amino acids identical to the hormone your hypothalamus releases in pulses. Its job is to tell the pituitary gland to secrete luteinizing hormone and follicle-stimulating hormone, which in turn act on the testes or ovaries. It is not a novel research compound; it is a copy of a hormone the body has always used.

Was gonadorelin ever an approved medicine?

Twice, in the United States. Drugs@FDA lists FACTREL under NDA 018123, in 0.1, 0.2 and 0.5 mg vials, and the LUTREPULSE KIT under NDA 019687, originally approved on 1989-10-10, in 0.8 and 3.2 mg vials. Every product under both applications is now marked Discontinued. So this is a compound with a genuine regulatory history that no longer has a marketed US product.

What were those approvals for?

Not for what it is sold for now. Factrel was a diagnostic agent — a way of testing whether a person's pituitary responds normally, by giving the hormone and measuring what comes out. Lutrepulse was a fertility treatment: a pump that delivered pulses to induce ovulation in women whose hypothalamus was not producing its own. Neither was a testosterone-support product.

Why does it matter that the dose is pulsed?

Because the same hormone does opposite things depending on how it arrives. In pulses it stimulates the pituitary to release LH and FSH. Delivered continuously, it desensitises the receptor and suppresses those same hormones — which is exactly how GnRH agonists are used to shut the axis down in prostate cancer and endometriosis. A hormone whose effect reverses with the delivery pattern is not one where a figure alone tells you anything.

Why is the research literature so large?

Because GnRH biology is central to reproductive medicine, so the 43,221 PubMed records and 2,456 randomized trials cover decades of work on the whole hormone system. Very little of it studies gonadorelin as it is sold today. A large literature attached to a compound's name is not the same as evidence for the use someone is selling it for, and this is the clearest example of that gap in the library.

What is it sold for now?

Mostly alongside testosterone replacement, on the argument that keeping the pituitary signal going preserves the testes' own function. That reasoning follows from the hormone's known mechanism, which is why it is plausible. It is not an approved indication, it is not what either US product was studied for, and the pulsatile-versus-continuous problem above applies directly to it.