Leuprorelin, also known as leuprolide, is a manufactured version of a hormone used to treat prostate cancer, breast cancer, endometriosis, uterine fibroids, as part of transgender hormone therapy, for early puberty, or to perform chemical castration of violent sex offenders. It is given by injection into a muscle or under the skin.
Leuprorelin is in the gonadotropin-releasing hormone (GnRH) analogue family of medications. It works by decreasing gonadotropin and therefore decreasing testosterone and estradiol. Common side effects include hot flashes, unstable mood, trouble sleeping, headaches, and pain at the site of injection. Other side effects may include high blood sugar, allergic reactions, and problems with the pituitary gland. Use during pregnancy may harm the baby.
Leuprorelin was patented in 1973 and approved for medical use in the United States in 1985. It is on the World Health Organization's List of Essential Medicines. It is sold under the brand name Lupron among others.
Medical use
Leuprorelin may be used in the treatment of hormone-responsive cancers such as prostate cancer and breast cancer. It may also be used for estrogen-dependent conditions such as endometriosis or uterine fibroids.
It may be used for precocious puberty in both males and females, and to prevent premature ovulation in cycles of controlled ovarian stimulation for in vitro fertilization (IVF). This use is controversial since the Lupron label advises against using the drug when one is considering pregnancy, due to a risk of birth defects.
It may be used to reduce the risk of premature ovarian failure in women receiving cyclophosphamide for chemotherapy.
Along with triptorelin and goserelin, it has been used to delay puberty in transgender youth until they are old enough to begin hormone replacement therapy. Researchers have recommended puberty blockers after age 12, when the person has developed to Tanner stages 2–3, and then cross-sex hormones treatment at age 16. This use of the drug is off-label, however, not having been approved by the Food and Drug Administration and without data on long-term effects of this use.
They are also sometimes used as alternatives to antiandrogens like spironolactone and cyproterone acetate for suppressing testosterone production in transgender women. It also is used for suppressing estrogen production in transgender men.
It is considered a possible treatment for paraphilias. Leuprorelin has been tested as a treatment for reducing sexual urges in pedophiles and other cases of paraphilia.
Side effects
Common side effects of leuprorelin injection include redness/burning/stinging/pain/bruising at the injection site, hot flashes (flushing), increased sweating, night sweats, tiredness, headache, upset stomach, nausea, diarrhea, impotence, testicular shrinkage, constipation, stomach pain, breast swelling or tenderness, acne, joint/muscle aches or pain, trouble sleeping (insomnia), reduced sexual interest, vaginal discomfort/dryness/itching/discharge, vaginal bleeding, swelling of the ankles/feet, increased urination at night, dizziness, breakthrough bleeding in a female child during the first two months of leuprorelin treatment, weakness, chills, clammy skin, skin redness, itching, or scaling, testicle pain, impotence, depression, or memory problems. The rates of gynecomastia with leuprorelin have been found to range from 3 to 16%.
A cohort of women that were prescribed leuprorelin to delay precocious puberty as children has developed osteoporosis and brittle teeth at an unexpected rate; However, the FDA has not established that these conditions were caused by leuprorelin.
Pharmacology
Mechanism of action
Leuprorelin is a gonadotropin-releasing hormone (GnRH) analogue acting as an agonist at pituitary GnRH receptors. Agonism of GnRH receptors initially results in the stimulation of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion by the anterior pituitary ultimately leading to increased serum estradiol and testosterone levels via the normal physiology of the hypothalamic–pituitary–gonadal axis (HPG axis); however, because propagation of the HPG axis is incumbent upon pulsatile hypothalamic GnRH secretion, pituitary GnRH receptors become desensitised after several weeks of continuous leuprorelin therapy. This protracted downregulation of GnRH receptor activity is the targeted objective of leuprorelin therapy and ultimately results in decreased LH and FSH secretion, leading to hypogonadism and thus a dramatic reduction in estradiol and testosterone levels regardless of sex.