What Is Leuprorelin? Definition and What Research Reports

Definition

Leuprorelin is a synthetic nonapeptide analogue of gonadotropin-releasing hormone (GnRH, also called luteinising hormone-releasing hormone or LHRH) that binds and activates the GnRH receptor on pituitary gonadotroph cells. It is known in much of the literature by the alternative international name leuprolide, and most clinical papers refer to the salt form leuprorelin acetate (leuprolide acetate). Structurally it is a modified version of the naturally occurring GnRH decapeptide, with substitutions that increase receptor affinity and slow enzymatic breakdown relative to the native hormone. Because sustained rather than pulsatile receptor stimulation eventually desensitises and downregulates the pituitary response, leuprorelin is classified pharmacologically as a GnRH agonist used for hormone suppression, and it is usually delivered as a long-acting depot rather than a short-acting injection.

This page is for educational purposes only and is not medical advice; consult a licensed physician about any medication, hormone therapy, or medical condition.

What Class of Molecule Is It, and Where Does It Come From?

Leuprorelin belongs to the peptide hormone analogue class — specifically the GnRH agonist family, which also includes goserelin, triptorelin, buserelin and nafarelin. It is not extracted from a biological source; it is produced by chemical peptide synthesis, then formulated. The parent molecule, GnRH, is a hypothalamic decapeptide that normally reaches the anterior pituitary in pulses and drives the release of luteinising hormone (LH) and follicle-stimulating hormone (FSH), which in turn regulate gonadal production of testosterone and oestradiol.

Analogue design changes the peptide backbone so that it resists the peptidases that clear native GnRH within minutes. The practical consequence in the literature is a molecule that can be delivered in sustained-release form. Depot formulation has itself been a research subject: an analytical study separated and identified acylated leuprorelin species formed inside poly(lactic-co-glycolic acid) (PLGA) microspheres, characterising peptide–polymer degradation products within the depot matrix (PMID 30731258). A separate pharmacokinetic and pharmacodynamic evaluation compared new prolonged-release leuprorelin acetate microspheres for injection with the reference product Enantone in healthy Chinese male volunteers (PMID 34372746). Together, those papers illustrate that in leuprorelin research the delivery system is often as much the study object as the peptide itself.

How the Term Is Used in Peptide Research

In peptide literature, "leuprorelin" appears in three distinct ways:

• As a named drug substance. Papers describe approved depot products and their pharmacology, most commonly under the names leuprorelin acetate or leuprolide acetate.
• As a comparator. Because it is a long-established GnRH agonist, leuprorelin is frequently the active control arm against which newer hormone-suppressing agents are measured — for example, an oral GnRH receptor antagonist, relugolix, was compared with leuprorelin in a phase 3, randomised, double-blind, noninferiority study in Japanese women with endometriosis-associated pain (PMID 34895700).
• As a pharmacological tool. Investigators use it to produce a reversible, drug-induced hypogonadal state in order to study what happens when sex-steroid signalling is suppressed, including downstream effects on tissue, bone and symptom profiles.

Note the agonist/antagonist distinction, which is a recurring source of confusion: leuprorelin activates the GnRH receptor and produces suppression indirectly through desensitisation, whereas agents such as relugolix block the receptor directly. The relugolix versus leuprorelin comparison described above sits squarely on that mechanistic contrast (PMID 34895700).

What the Published Literature Reports

The published record for leuprorelin is clinical rather than exploratory, and it spans several unrelated fields. The summary below reflects what the cited papers stated they examined; no outcome is described beyond the scope of the paper attached to it.

Gynaecological and endocrine contexts

In the endometriosis setting, researchers ran a phase 3, randomised, double-blind, noninferiority trial reporting that oral relugolix reduced endometriosis-associated pain compared with leuprorelin in Japanese women (PMID 34895700). In paediatric endocrinology, a multicentre, randomised, parallel, controlled trial evaluated the efficacy and safety of a domestically produced leuprorelin in girls with idiopathic central precocious puberty (PMID 25963350). A published case report described the multifactorial aetiology and management of premenstrual dysphoric disorder involving leuprorelin acetate (PMID 38160030).

Neuromuscular disease

Leuprorelin has been studied in spinal and bulbar muscular atrophy (SBMA, Kennedy's disease), a condition linked to androgen receptor pathology. A pre- and post-marketing observational study assessed the therapeutic impact of leuprorelin acetate in SBMA (PMID 41258507). A separate case report documented castration-resistant prostate cancer diagnosed during leuprorelin treatment given for SBMA (PMID 35795131).

Other reported contexts

A preclinical paper reported a protective effect of leuprorelin on radiation-induced intestinal toxicity (PMID 26124333). In forensic psychiatry, a study examined therapeutic effects of leuprorelin (leuprolide acetate) in sexual offenders with paraphilia (PMID 30190656).

Adverse Events and Tolerability: What Studies Report

Reports in this literature largely concern consequences of suppressed sex-steroid signalling and of injection-based depot delivery. A case report described a patient with paraphilia who had osteoporosis and was administered depot leuprorelin, linking the clinical picture to prolonged hormone suppression (PMID 31635190). A dermatological case report documented diffuse maculopapular dermatitis associated with leuprorelin acetate androgen deprivation therapy (PMID 39176344). Menopause-like symptoms arising during treatment have also been studied as an outcome in their own right: a randomised controlled trial reported that the probiotic Limosilactobacillus reuteri NCU-37 alleviated leuprorelin-induced perimenopausal syndrome in infertile women, with gut microbiota modulation proposed as the mechanism (PMID 41399984). A further case report noted castration-resistant prostate cancer diagnosed during leuprorelin treatment in a patient with SBMA (PMID 35795131).

Case reports describe single patients and cannot establish how often an event occurs; randomised trials in one population do not transfer automatically to another. Nothing here should be read as a safety profile.

Naming, Regulatory Status and Common Confusions

Leuprorelin is the international nonproprietary name; leuprolide is the equivalent name used in the United States, and products are marketed as leuprorelin/leuprolide acetate depots under several brand names, one of which — Enantone — appeared as the reference comparator in a comparative pharmacokinetic and pharmacodynamic study in healthy male volunteers (PMID 34372746). It is a prescription pharmaceutical in the jurisdictions where it is approved, not a research-only chemical, and it is distinct from the GnRH antagonists it is often compared against (PMID 34895700). It is also unrelated to growth hormone secretagogues, melanocortin peptides, or repair peptides despite all being grouped loosely as "peptides" in non-technical writing.

Limitations of This Entry

This is a definitional reference entry. It does not list doses, schedules, formulation choices or monitoring, and it makes no comparison of one product against another beyond what the cited papers themselves reported. Readers evaluating leuprorelin research should read the primary sources, since indication, population, formulation and study design differ substantially between the papers cited here.

References

• Relugolix, an oral gonadotropin-releasing hormone receptor antagonist, reduces endometriosis-associated pain compared with leuprorelin in Japanese women: a phase 3, randomized, double-blind, noninferiority study (Fertility and Sterility, 2022)
• Therapeutic impact of leuprorelin acetate on spinal and bulbar muscular atrophy: pre- and post-marketing observational study (Journal of Neurology, 2025)
• Protective Effect of Leuprorelin on Radiation-induced Intestinal Toxicity (Anticancer Research, 2015)
• Therapeutic Effects of Leuprorelin (Leuprolide Acetate) in Sexual Offenders with Paraphilia (Journal of Korean Medical Science, 2018)
• Diffuse Maculopapular Dermatitis Associated With Leuprorelin Acetate Androgen Deprivation Therapy (Cureus, 2024)
• Separation and identification of acylated leuprorelin inside PLGA microspheres (International Journal of Pharmaceutics, 2019)
• A Case of Paraphilia with Osteoporosis and Administered with Depot Leuprorelin (Medicina, 2019)
• Limosilactobacillus reuteri NCU-37 alleviates leuprorelin-induced perimenopausal syndrome in infertile women by modulating the gut microbiota: a randomized controlled trial (Food & Function, 2026)
• Castration-resistant prostate cancer diagnosed during leuprorelin treatment for spinal and bulbar muscular atrophy (IJU Case Reports, 2022)
• The multifactorial aetiology and management of premenstrual dysphoric disorder with leuprorelin acetate (BMJ Case Reports, 2023)
• Pharmacokinetic and pharmacodynamic evaluation of the new prolonged-release leuprorelin acetate microspheres for injection compared with Enantone in healthy Chinese male volunteers (Expert Opinion on Drug Metabolism & Toxicology, 2021)
• Efficacy and safety of domestic leuprorelin in girls with idiopathic central precocious puberty: a multicenter, randomized, parallel, controlled trial (Chinese Medical Journal, 2015)