GnRH agonists reduce pelvic blood flow. They can be very effective in reducing pelvic pain in association with endometriosis. The big question with GnRH agonists is why they MUST be stopped after six months in women with chronic pelvic pain. They are given for years in people with cancer. The primary reason is the loss of bone density which may be ameliorated by giving concurrent HRT e.g. tibolone (Livial). Nevertheless there are studies that describe effective treatment of chronic pelvic pain with carefully-monitored, long-term GnRH agonists. It may be that cost is a consideration since each injection cost GBP100 (USD150). For chronic pain that may be seen as unfair and unreasonable.
GnRH agonists include leuprolide (Lupron), buserelin (Suprefact, Suprecor), nafarelin (Synarel), histrelin (Supprelin), goserelin (Zoladex),
deslorelin (Suprelorin, Ovuplant), Triptorelin.
Administration
These medications can be administered intranasally, by injection, or by implant. Injectables have been formulated for daily, monthly, and quarterly use; and implants can last from 1 to 12 months.
GnRH agonists are useful in the treatment of management of female disorders that are dependent on estrogen productions. Women with menorrhagia, endometriosis, adenomyosis, or uterine fibroids may receive GnRH agonists to suppress ovarian activity and induce a hypoestrogenic state.
Side effects of the GnRH agonists are signs and symptoms of hypoestrogenism, including hot flushes, headaches, and osteoporosis. In patients under long-term therapy, small amounts of estrogens could be given back (“add-back regimen”) to combat such side effects and to prevent bone wastage. Generally, long-term patients, both male and female, tend to undergo annual DEXA scans to appraise bone density.
Zoladex
Zoladex (Goserelin) is a synthetic analogue (artificial copy) of the natural female hormone Gonadotrophin Releasing Hormone (GnRH) and is a GnRH agonist (works against). Zoladex is made by AstraZeneca. Zoladex works by blocking the production of natural Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH), which are produced by the pituitary gland at the base of the brain. Without FSH and LH the ovaries will not produce oestrogen. Zoladex reduces the symptoms of endometriosis including the pain.
Zoladex comes as a single dose syringe applicator with 3.6mg depot injection (it slowly releases the drug over four weeks)
Zoladex is given as a single injection into the abdomen subcutaneously (under the skin) every four weeks
Zoladex can be started at any time during the monthly cycle and is given for a course of six months.
Contra-indications include Pregnancy, Lactating women (breast feeding), Known hypersensitivity to GnRH Analogues
Zoladex should not be used for more than one course of six months as it can cause loss of bone density
Zoladex should be used with caution in women with known metabolic bone disease
Side effects of Zoladex include Hot flushes, Dry vagina, Mood changes, Headache, Sweating, Loss of sex drive, Depression, Change in breast size. The above side effects seldom require that the treatment be stopped.
Make sure that you are not pregnant before starting treatment. A pregnancy test is advisable.
Barrier methods of contraception should be used during treatment (until periods restart), as Zoladex is not a contraceptive. Periods generally return within two to three months after completion of treatment.
It is advisable to have one period before trying for pregnancy. Some patients have a loss of bone density during treatment with Zoladex. This should be reversed within about six months of the treatment ending. Patients who are underweight, smoke, have a familial history of osteoporosis or are approaching the menopause may wish to assess the risk factors of bone loss.