Pharmacology · GnRH analogues (agonists and antagonists)
Leuprorelin !
An injected hormone that, given continuously, switches off testosterone and oestrogen. It treats prostate cancer, endometriosis, fibroids and early puberty.
Updated 2026-11-01
Also called: leuprolide
Mechanism of action
Leuprorelin is a long-acting GnRH agonist. Given continuously it first raises LH, FSH and sex steroids, then desensitises the pituitary GnRH receptors. LH and FSH fall, and with them testosterone in men and oestrogen in premenopausal women, producing a reversible medical castration.
- Binds and stimulates the pituitary GnRH receptor
- Brief rise in LH, FSH and sex steroids (flare)
- Continuous stimulation desensitises the receptors
- LH and FSH fall: testosterone or oestrogen drop
Pharmacokinetics
- Absorption
- Injected under the skin or into muscle; depot forms release it slowly over weeks to months
- Metabolism
- Broken down by peptidases into smaller inactive peptides
- Half-life
- About 3 hours for the plain solution; depot forms give a long, steady effect
- Onset and duration
- Testosterone rises in the first days and falls to castration levels within a few weeks
Indications
- Advanced prostate cancer Prostate cancer →
- Endometriosis Endometriosis →
- Anaemia caused by uterine fibroids Uterine fibroids (leiomyomas) →
- Central precocious puberty
Adverse effects
Common
- Hot flashes and sweating
- Loss of libido and erectile dysfunction
- Injection-site pain or redness
- Tiredness
- Breast tenderness or change in breast size
Contraindications
- Hypersensitivity to GnRH, GnRH agonists or any excipient
- Pregnancy
Key interactions
- Drugs that prolong the QT interval
- Additive QT prolongation.
- Antidiabetic medicines
- Glycaemic control may worsen; treatment may need review.
What is monitored
- Testosterone and PSA in prostate cancer
- Blood glucose or HbA1c
- Cardiovascular symptoms and risk factors
- ECG and electrolytes in patients at risk of QT prolongation
- Bone density with long treatment
Administration and safety
- Given by subcutaneous or intramuscular injection; there are daily solutions and depot forms with different routes and schedules, so the exact product is checked.
- Rotate injection sites; local redness and hardening can occur.
- Depot suspensions are prepared exactly as the product instructions describe.
Nursing care
- In the first weeks of prostate cancer treatment, watch for new bone pain, difficulty passing urine, leg weakness or numbness: possible flare or spinal cord compression.
- Teach about hot flashes, sexual effects and mood changes.
- Check glucose in people with diabetes or risk factors.
- Rotate and inspect injection sites.
- Women of reproductive age need non-hormonal contraception; menstruation usually stops.
Pregnancy and breastfeeding
Contraindicated in pregnancy; it may cause fetal harm.
Test yourself
Think of the answer, then tap the question to see it.
Why can leuprorelin briefly worsen bone pain in metastatic prostate cancer?
As an agonist it first raises LH and testosterone before the pituitary desensitises; the testosterone surge can stimulate the tumour for a few weeks.
How does continuous leuprorelin differ from pulsatile GnRH?
Pulsatile GnRH keeps LH and FSH secretion going; continuous exposure desensitises the receptors and shuts down LH, FSH and sex steroid production.
Which laboratory test checks for a metabolic adverse effect of leuprorelin in men?
Blood glucose or HbA1c, because GnRH agonists can cause hyperglycaemia and diabetes.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Leuprolide Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); DailyMed - LEUPROLIDE ACETATE kit (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 46 (McGraw Hill, 2023).
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