Leuprorelin: Mechanism of Action, Indications and Important Notes
Leuprorelin is a synthetic peptide from the group of gonadotropin-releasing hormone analogues (GnRH analogues). It is used in medicine to suppress the production of the sex hormones testosterone and oestrogen in the body. The effect is based on a paradoxical principle: although leuprorelin is structurally similar to endogenous GnRH, its continuous use leads to a reduction in sex hormone levels. This effect is utilised in various medical specialities, including oncology, gynaecology and urology.
Mechanism of Action
Under normal physiological conditions, GnRH is released pulsatilely from the hypothalamus. This pulsatile release stimulates the pituitary gland to release LH (luteinising hormone) and FSH (follicle-stimulating hormone). LH in turn stimulates the testes to produce testosterone and the ovaries to produce oestrogen.
As a GnRH analogue, leuprorelin binds to GnRH receptors in the pituitary gland. Unlike pulsatile natural GnRH, leuprorelin stimulates these receptors continuously. After an initial brief activation phase, this continuous stimulation leads to desensitisation and down-regulation of GnRH receptors. As a result, LH and FSH are barely secreted, and the production of testosterone and oestrogen in the gonads falls to very low levels.
This state is referred to as pharmacological castration, although the gonads remain physically intact. After discontinuation of leuprorelin, hormone production generally returns to normal, which distinguishes leuprorelin from a surgical procedure. However, at the start of therapy there is initially a brief increase in sex hormones (the so-called flare effect) before suppression sets in.
Indications
Prostate Cancer
The most important oncological indication for leuprorelin is prostate cancer. Prostate cancer cells are often hormone-dependent in early stages of the disease, meaning testosterone promotes their growth. By suppressing androgens with leuprorelin, the growth signals for these cells are reduced. Leuprorelin is used both as monotherapy and in combination with further hormonal therapies or radiotherapy. It is part of so-called androgen deprivation therapy, which plays a central role in the guideline-based treatment of prostate cancer.
Endometriosis
Endometriosis is a gynaecological condition in which tissue similar to the uterine lining occurs outside the uterus and grows under the influence of oestrogens. By suppressing oestrogen with leuprorelin, the activity of ectopic endometrial tissue can be inhibited. Leuprorelin is used for moderate to severe endometriosis when other treatment options are insufficient or unsuitable. A so-called add-back therapy with low-dose oestrogen can be used concurrently to mitigate oestrogen deficiency symptoms such as bone density loss and hot flushes.
Uterine Fibroids
Uterine fibroids are benign smooth muscle tumours of the uterus that also grow in an oestrogen-dependent manner. Leuprorelin can be used before surgery to reduce fibroid size and decrease blood loss during the operation. Long-term use is time-limited due to bone density loss.
Precocious Puberty
In central precocious puberty (pubertas praecox), where puberty begins at a very young age due to premature activation of the hypothalamic-pituitary axis, leuprorelin is used to delay pubertal development and preserve height. Treatment must begin early and is continued until the appropriate pubertal age.
Breast Cancer
In premenopausal women with hormone receptor-positive breast cancer, leuprorelin can be used to suppress ovarian function in order to minimise oestrogen production. This is done in combination with other antihormonal agents such as tamoxifen or aromatase inhibitors.
Dosage Forms and Dosing
Leuprorelin is not taken orally, as it would be broken down in the gastrointestinal tract as a peptide. It is available as a depot injection preparation for subcutaneous or intramuscular injection. Depot formulations release the active substance in a controlled manner over a defined period, enabling monthly, three-monthly or six-monthly administration depending on the formulation. This considerably improves treatment adherence compared to daily oral intake. Depot injections are generally administered by a physician.
The Flare Effect and Its Significance
At the start of leuprorelin therapy, there is a temporary increase in LH, FSH and testosterone for approximately one to two weeks. In prostate cancer patients, this testosterone rise can lead to a temporary worsening of symptoms, for example increased bone pain in patients with bone metastases or, in rare cases, spinal cord compression with vertebral metastases. To mitigate this flare effect, prostate cancer patients are often given a concomitant antiandrogen such as bicalutamide during the first weeks of therapy.
Adverse Effects
The side effects of leuprorelin are primarily attributable to the induced hormone deficiency:
- Hot flushes are very common and for many patients the most burdensome side effect
- Loss of libido and sexual dysfunction in men and women
- Decreased bone density (osteoporosis) with long-term use; regular bone density measurements and, if necessary, treatment with bisphosphonates or other bone-protective agents are recommended
- Muscle wasting and weight gain, particularly visceral fat
- Fatigue and reduced performance
- Cognitive changes and mood swings have been reported
- Local injection site reactions such as redness, swelling or pain
- Gynaecomastia (breast tissue growth) can occur in men
- Increased risk of cardiovascular disease with long-term use has been described and requires cardiological monitoring
Leuprorelin on Sanoliste
On Sanoliste you will find urologists, gynaecologists and oncologists who offer specialised medical support for the conditions for which leuprorelin is used. Therapy with leuprorelin requires regular monitoring, including of hormone levels, bone density and other parameters.
The content of this page is for general information purposes only and does not replace consultation with a physician. Leuprorelin is a prescription-only medicine and may only be used under medical supervision.
Frequently Asked Questions about Leuprorelin
How long does it take for leuprorelin to work?
After the first injection of leuprorelin, there is initially a brief increase in sex hormones, the so-called flare effect. This lasts approximately one to two weeks. After that, hormone levels begin to fall, and the castration range is generally reached within two to four weeks after the first dose. Complete suppression of testosterone production is therefore only achievable after several weeks. For this reason, an antiandrogen is often administered concomitantly at the beginning.
Is the effect of leuprorelin reversible after discontinuation?
In most patients, hormone levels return to normal after discontinuation of leuprorelin, provided the gonads are still functional. However, the time to normalisation can vary and may take several months. After a longer duration of therapy, recovery may take longer. In older men, testosterone regeneration after prolonged androgen suppression is sometimes incomplete. Expectations regarding a possible recovery should be discussed realistically with the treating physician.
What measures help against bone density loss under leuprorelin?
Bone density loss under androgen deprivation with leuprorelin is a serious long-term risk. Recommended protective measures include regular bone density measurements (DXA scans), adequate calcium and vitamin D intake, and physical activity with strength training. In cases of demonstrated significant bone density loss or increased fracture risk, bone-protective medications such as bisphosphonates or denosumab may be used. The individual strategy is determined by the treating physician.