Suprefact (buserelin acetate), marketed by Sanofi, is a medication for the treatment of endometriosis. It is available as a nasal spray or under-the-skin injection.

Suprefact eases symptoms associated with the condition.

How Suprefact works

The production of sex hormones, such as estrogen, is regulated by the gonadotropin-releasing hormone (GnRH). Increased production of estrogen during the menstrual cycle thickens the endometrial tissue lining the uterus. In this process, GnRH is released by the hypothalamus and stimulates the secretion of sex hormones by activating receptors in the pituitary gland.

Suprefact is a GnRH receptor agonist, meaning that it binds to and activates the same receptor, but binds more strongly and dissociates more slowly than natural GnRH. So initially, Suprefact binding leads to an increase in estrogen production. However, in response to the continuous stimulus, the pituitary gland shuts down GnRH receptors and thereby becomes insensitive to the action of GnRH and its agonists. As a consequence, Suprefact suppresses estrogen synthesis, which stops the menstrual cycle.

In endometriosis, estrogen stimulates the growth of endometriotic lesions outside the uterus. With the suppression of sex hormones, Suprefact may inhibit this growth.

Suprefact in clinical trials

In a clinical trial including 35 women with endometriosis stage 1 or 2, participants were randomized to receive either 1,200 ug of intranasal Suprefact per day for six months or no treatment.

None of the women experienced painful periods during treatment. After three months of follow-up, menstrual pain recurred in 27 percent of these patients. In the untreated group, 81 percent reported painful menstrual cycles, while others reported a spontaneous and complete remission of the symptoms.

Five women with pelvic pain reported complete resolution of the symptoms during treatment that persisted through the follow-up period. In the untreated group, pelvic pain resolved spontaneously in one patient and persisted in two others.

Of three women who experienced painful intercourse, two had a complete, and one had a partial remission during treatment. In those with complete remission, symptoms did not recur during follow-up. Five women in the untreated group also experienced painful intercourse, symptoms disappeared in two and remained unchanged in the other three.

A multicenter Phase 3 randomized, double-blind clinical trial compared the effect of dienogest, a progestin medication, with Suprefact.

During the trial, 271 women with endometriosis were randomized to receive either 300 ug of intranasal Suprefact three times daily or a 1 mg dienogest tablet twice daily for 24 weeks. Eight patients in each group were given tablet or intranasal placebos and served as controls.

Pain scores decreased in both treatment groups to a comparable degree. The loss in bone mineral density was higher in the Suprefact group than in the dienogest group (-1 percent in the dienogest group, -2.6 percent in the Suprefact group). Genital bleeding occurred less frequently, and hot flashes more frequently, in patients treated with Suprefact than with dienogest.

In a randomized study of 62 infertile women with endometriosis, participants were treated either with 1,200 ug per day intranasal Suprefact or 600 ug per day oral danazol, a synthetic androgen.

During the six-month treatment period, pain symptoms were markedly lower in both groups. Post-treatment laparoscopy done on 25 consenting patients did not reveal significant differences in effects on endometriotic lesions. In the Suprefact group, 48 percent became pregnant within 18 months after treatment, and 43 percent in the danazol group. One year after stopping treatment, about half of patients in each group reported a return of pain symptoms, but treatment side effects were less severe in the Suprefact group.  

Additional information

Common side effects of Suprefact include hot flashes, heavy bleeding, headache, vaginal dryness, and decreased libido.


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