New drug approved for endometriosis pain treatment

A new drug for pain associated with endometriosis may soon be available after being approved by the US Food and Drug Administration (FDA).

Elagolix, approved under the brand name Orilissa, becomes the first FDA-approved oral treatment for the management of severe pain associated with endometriosis in over a decade.

The drug, a gonadotropin-releasing hormone (GnRH) antagonist, and the first of its kind to be approved specifically for endometriosis, is expected to be in US pharmacies in August.

Endometriosis is a debilitating gynaecological condition in which the cells that line the womb grow elsewhere in the body too.

This means that every month they build up and shed as a monthly period. However, as the blood has nowhere to go, it remains in the body as scar tissue, causing chronic pain, and sometimes resulting in infertility.

The condition affects an estimated one in 10 women of reproductive age and women have told of experiencing waits of up to ten years for a diagnosis, which can only be done via laparoscopy.

Currently, there is no cure for endometriosis. Women are placed on hormonal contraception, or given hormonal medication like GnRH antagonists, and pain is treated with nonsteroidal anti-inflammatory drugs (NSAIDs), although none of these are specifically targeted for endometriosis.

Sometimes, women can undergo surgery to remove built up scar tissue, but this does not stop the endometriosis recurring.

Study investigator for the drug Dr. Hugh Taylor said: “Endometriosis is often characterised by chronic pelvic pain that can impact women’s daily activities.

“Women with endometriosis may undergo multiple medical treatments and surgical procedures seeking pain relief, and this approval gives physicians another option for treatment based on a woman’s specific type and severity of endometriosis pain.”

To get FDA approval, data from two replicate studies was used in the largest endometriosis Phase 3 study program conducted to date, evaluating nearly 1,700 women with moderate to severe endometriosis pain.

The trials showed that Orilissa significantly reduced the three most common types of pain associated with endometriosis: daily menstrual pelvic pain, non-menstrual pelvic pain, and pain with sex.

Women responded better to Orilissa, both at 150mg once daily and 200mg twice daily, when treated for daily menstrual pain and non-menstrual pelvic pain compared with a placebo after three months.

Both treatment groups showed decreases by month six and clinical data also demonstrated that women taking the drug at a 200mg dose twice daily showed greater reduction in pain during sex by month three when compared with a placebo.

The trials showed that Orilissa significantly reduced the three most common types of pain associated with endometriosis: daily menstrual pelvic pain, non-menstrual pelvic pain, and pain with sex.

The recommended duration of use for Orilissa is up to 24 months for the 150mg once daily dose, and six months for the 200mg twice daily dose, however, as it causes a dose-dependent decrease in bone mineral density.

This decrease increases in duration of use of the drug, and may not be completely reversible after stopping treatment.

While the drug could offer many patients with endometriosis new hope when other methods of pain relief haven’t proved effective, then, it doesn’t come without side effects.

On top of bone density loss, Orilissa hasn’t been tested with hormonal contraceptives, as birth control pills containing oestrogen may make it less effective, and it is unknown how well it works with progesterone only forms of contraception.

The drug can cause suicidal thoughts, actions, or behaviour, or worsening mood. It can also affect the liver in some cases.

Common side effects include hot flushes or night sweats, headache, nausea, difficulty sleeping, absence of periods, anxiety, joint pain and depression.

How do GnRH antagonists work?

GnRH antagonists compete with natural GnRH for binding to GnRH receptors, meaning that they decrease, or block entirely, GnRH’s effect on the body.

When it comes to the female reproductive cycle, the body needs GnRH to release follicle-stimulating hormone (FSH) and luteinising hormone (LH) from the pituitary gland.

Once these hormones have been released they stimulate ovulation and cause the corpus luteum (a matured sack that has released its egg) to release oestrogen and progesterone.

So, GnRH forms part of the massive chain reaction of hormone rises and falls that keep eggs developing and the womb lining growing and shedding each month.

In terms of treatment for endometriosis, as GnRH antagonists stop production of oestrogen, this depletes oestrogen levels in the endometrium (womb lining).

Therefore, women taking GnRH antagonists will, after a short period, stop bleeding monthly. Endometriosis is dependent on oestrogen, so blocking oestrogen will prevent the progression of the disease.

Featured image shows pot of pills lying on its side with some of the pills spilled out.

Page last updated July 2018