Ryeqo, a medicine used to treat uterine fibroids, has just been approved for marketing specifically for endometriosis

Endometriosis affects 14% of women of reproductive age. While we don’t have a full understanding of the cause, the evidence suggests it’s due to body tissue that is similar to the lining of the uterus (called the endometrium) growing outside the uterus. This causes pain and inflammation, which reduces quality of life and can also affect fertility.

What does Ryeqo do?

Ryeqo is a tablet containing three different active ingredients: relugolix, estradiol and norethisterone.

Relugolix is a drug that blocks a particular peptide from releasing other hormones. It is also used in the treatment of prostate cancer. Estradiol is a naturally occurring oestrogen hormone in women that helps regulate the menstrual cycle and is used in menopausal hormone therapy. Norethisterone is a synthetic hormone commonly used in birth control medications and to delay menstruation and help with heavy menstrual bleeding.

All three components work together to regulate the levels of oestrogen and progesterone in the body that contribute to endometriosis, alleviating its symptoms.

Relugolix reduces the overall levels of oestrogen and progesterone in the body. The estradiol compensates for the loss of oestrogen because low oestrogen levels can cause hot flushes (also called hot flashes) and bone density loss. And norethisterone blocks the effects of estradiol on the uterus (where too much tissue growth is unwanted).

Is it really new?

The maker of Ryeqo claims it is the first new drug for endometriosis in Australia in 13 years.

But individually, all three active ingredients in Ryeqo have been in use since 2019 or earlier.

Ryeqo has been available in Australia since 2022, but until now was not specifically indicated for endometriosis. It was originally approved for the treatment of uterine fibroids, which share some common symptoms with endometriosis and have related causes.

Who can prescribe it?

Like other hormonal therapies outside of combined oral contraceptives or progestogens, Ryeqo must be initiated by a specialist.

Who is it for?

According to the PI, Ryeqo is recommended for women who have had previous medical or surgical treatment for endometriosis. For example, those who are unresponsive and still symptomatic.

It may be particularly beneficial for women with both uterine fibroids and endometriosis, since the medicine treats both, and they can appear together.

How to take it

Ryeqo is a once-a-day tablet that can be taken with or without food, but should be taken about the same time each day.

It is recommended that women start taking Ryeqo within the first five days after the start of their next period. If they start at another time during their period, they may experience initial irregular or heavier bleeding.

Possible interactions and adverse effects

Because it contains both synthetic and natural hormones, Ryeqo and the contraceptive pill can’t be used together. However, because Ryeqo does contain norethisterone, it can be used as contraception, although it will take at least one month of use to be effective. People taking  Ryeqo should use a non-hormonal contraceptive – such as condoms – for a month when starting the medicine.

Ryeqo may be incompatible with other medicines. It might not be suitable for those who take medicines for epilepsy, HIV and AIDS, hepatitis C, fungal or bacterial infections, high blood pressure, irregular heartbeat, angina), or organ rejection It is also contraindicated in those who have a liver tumour or liver disease.

The possible side effects of Ryeqo are similar to those of oral contraceptives. Blood clots are a risk with any medicine that contains an oestrogen or a progestogen, which Ryeqo does. Other potential side effects include bone loss, a reduction in menstrual blood loss or loss of your period.

It’s costly for now

Ryeqo can now be prescribed in Australia, but it is not yet available on the PBS.

While the maker has made a submission to the Pharmaceutical Benefits Advisory Committee, it is not yet subsidised by the Australian government. This means that rather than paying the normal PBS price of up to A$31.60, it has been reported it may cost as much as $135 for a one-month supply. The committee will make a decision on whether to subsidise Ryeqo at its meeting in March.

Key points for GPs:

• Pregnancy must be ruled out before prescribing; hormonal treatments aren’t recommended for those wanting to conceive because it impairs short-term conception. (Surgery is first choice treatment for infertility associated with endometriosis.)
• Ryeqo has as many risks and interactions as any other hormonal treatment so proceed with due care.
• Complete family and medical history checks, blood pressure checks, physical examination, review of contraindications are all required prior to treatment.

This article was adapted with permission from the authors. It was first published in The Conversation under a Creative Commons license. Read the original article.