What is endometriosis?
Endometriosis is characterized by endometrial-like tissue growing elsewhere in the abdomen, sometimes on the outside of the uterus, or on the bowel or bladder, forming lesions. (The endometrium is the tissue that normally lines the uterus). Both normal and abnormal endometrial tissue swells and sheds in response to the hormone cycle, which controls menstruation. The endometrial lesions swell, but cannot be expelled properly because they are not located within the uterus. This leads to inflammation, causing pain and infertility in more severe cases.
How triptorelin works
Triptorelin is a gonadotropin-releasing hormone (GnRH) receptor agonist. It binds and activates the same receptor that GnRH activates in the hypothalamus. The hypothalamus is considered the “master switch” in the brain for hormone secretion. Activating the GnRH receptor causes a brief increase in estrogen, but then the receptor becomes desensitized to naturally produced GnRH, so estrogen production in the ovaries drops dramatically.
Without estrogen, the endometrial lesions shrink and pain and inflammation are reduced.
Triptorelin is injected under the skin or into the muscle of the buttock once a month or once every three months.
Triptorelin in clinical trials for endometriosis
A Phase 3 clinical trial (NCT03232281) is recruiting 300 endometriosis patients in China to assess the efficacy of triptorelin three-month formulation (one injection) compared to triptorelin one-month formulation (three injections). Patients will be randomly assigned to each group. Blood samples will be taken at the start of the trial and at one, two, and three months to assess estrogen levels.
Another clinical trial (NCT01942369) was recently completed. It was aimed at describing changes in the intensity of specific endometriosis symptoms before surgery (baseline), after surgery and during subsequent continuous triptorelin treatment for up to six months. Symptoms were assessed visually every three months in the first 12 months after surgery, then every six months for one year after that. The results have not yet been published.
A Phase 3 clinical trial (NCT01973816) is recruiting 78 patients with rectal endometriosis in France to test whether continuous hormonal treatment brings about better digestive functional outcomes than curative rectal surgery. Patients will be randomly assigned for either triptoreline and add-back estradiol therapy during six months, followed by daily cyproterone (an anti-androgen) and add-back therapy for 18 months, or rectal surgery combined with add-back estradiol therapy and cyproterone. The primary outcomes will be digestive health as assessed by the Knowles-Eccersley-Scott-Symptom Questionnaire and Gastrointestinal Quality of Life Index (GIQLI) score. Both surveys assess bowel movements and digestive discomfort.
A Phase 4 clinical trial (NCT00735852) was recently completed. The study was a “within-patient comparison study” to assess the efficacy and safety of triptoreline when administered in combination with tibolone (an add-back therapy) for the treatment of women with chronic cyclical pelvic pain. The 31 patients in the study were treated every three months for two years. Patients’ pain and quality of life were assessed via questionnaire at three, six, 12, 18 and 24 months after the baseline visit.
Triptorelin can cause side effects, including hot flashes, pain or irritation at the injection site, headache, nausea, and vaginal bleeding.
Some physicians may recommend combining triptorelin with an add-back hormonal therapy that contains a low does of estrogen or progestin to reduce the side effects of the treatment.
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