Selective estrogen receptor modulators (SERMs): Uses, common brands, and safety info

Selective estrogen receptor modulators, otherwise known as SERMs, are prescription agents that interact with estrogen receptors throughout the body. Whether they serve as inhibitors or initiate action at that receptor is dependent upon the type of tissue where the receptor is located. SERMs are used in a variety of types of diagnoses such as osteoporosis and breast cancer. 

Osteoporosis is a disease of the bones that typically occurs after the onset of menopause where both bone mass and bone mineral density decrease. The overall quality of the bone begins to decay and leads to bone loss. This leaves patients at an increased risk of bone fractures and severe falls. SERMs are just one type of treatment for osteoporosis. Weight-bearing exercise, calcium and vitamin D supplementation, or bisphosphonates may also be recommended by your endocrinology specialist.

Breast cancer is the second most common cancer in women. Some types of breast cancer are dependent upon estrogen to grow. SERMs are a treatment option for these types of breast cancer as they have antagonist activity at the estrogen receptor. 

What are selective estrogen receptor modulators?

Selective estrogen receptor modulators (SERMs) are a group of prescription medications that act upon estrogen receptors in different tissues throughout the body. The effect of SERMs depends upon the tissue where the estrogen receptor is located.

How do selective estrogen receptor modulators work?

Selective estrogen receptor modulators can be either agonists or antagonists at the estrogen receptor. Simply put, this means that the mechanism of action of SERMs may either initiate or block activity at estrogen receptors. In breast tissue, for instance, SERMs block the estrogen molecule from the estrogen receptor on the breast tissue. This keeps estrogen from feeding the growth of the types of breast cancer dependent upon estrogen to grow. This can reduce the incidence of breast cancer or treat existing breast cancer. The pharmacology of SERMs is different in bone tissue. SERMs have an agonist type relationship with estrogen receptors in the bone to promote bone growth in postmenopausal osteoporosis.

SERMs are sometimes used without Food and Drug Administration approval by weight lifters who utilize anabolic steroids. Long term anabolic steroid use can lead to gynecomastia, or an undesirable growth of the breast tissue in men. The SERM selectivity for the estrogen receptor in breast tissue needed for breast tissue growth helps block these receptors. These antagonist effects are thought to decrease the growth of breast tissue.

What are selective estrogen receptor modulators used for?

• Osteoporosis treatment

• Osteoporosis prophylaxis

• Breast cancer treatment

• Breast cancer prophylaxis

• Vaginal dryness

• Uterine leiomyomata**

• Malignant melanoma**

• Malignant glioma**

• Infertility**

** Off-label use only

Types of selective estrogen receptor modulators 

SERMs intended to treat breast cancer 

Select SERMs are approved by the Food and Drug Administration (FDA) in the treatment and prevention of breast cancer. The cancer types include estrogen receptor positive breast cancer or tumors where estrogen receptor status is unknown. These cancer types may still be localized to the breast tissue only or contained within the ducts in a breast cancer type known as ductal carcinoma in situ (DCIS). The cancer may also be metastatic, or spread to other tissues or organs within the body. The antagonist effects of tamoxifen and similar SERMs at the estrogen receptor deny the tumor what it needs to grow. SERMs may be used as adjuvant agents for treatment, meaning they are used alongside other agents to treat cancer. SERMs are also used to reduce the risk of breast cancer in patients with a family history. Lasofoxifene is a second-generation SERM currently undergoing clinical trials for the treatment of breast cancer.

Examples of SERMs used to treat or prevent breast cancer: Evista (raloxifene), Nolvadex (tamoxifen), Soltamox (tamoxifen), and Fareston (toremifene)

SERMs intended to treat osteoporosis

SERMs serve as an estrogen agonist in bone. The effects of raloxifene reduce the resorption of bone and increase bone mineral density in post-menopausal women. This in turn improves the quality of the bone. There are new SERMs in the investigative stage for osteoporosis. The chemical names of the investigative SERMs are bazedoxifene and lasofoxifene. They are currently in clinical trials. Ask your endocrine specialist for more details about these drugs,

Examples of SERMs used in the treatment of osteoporosis: Evista (raloxifene)

SERMs used to treat vaginal dryness

SERMs produce effects of estrogen on vaginal tissue in women who are post-menopausal. This inhibits vaginal atrophy by increasing superficial cells and decreasing parabasal cells. This reduces vaginal pH and relieves dryness (dyspareunia).

Examples of SERMs used to treat vaginal dryness: Osphena (ospemifene)

Who can take selective estrogen receptor modulators?

Can men take selective estrogen receptor modulators?

Adult males may take tamoxifen (Nolvadex or Soltamox) for the treatment of breast cancer. Other SERMs are not indicated for treatment in males.

Can women take selective estrogen receptor modulators?

Adult women may take any of the SERMs currently on the market. The choice of SERM would be dependent upon the target tissue or indication.

Can you take selective estrogen receptor modulators while pregnant or breastfeeding?

Most uses for SERMs are in post-menopausal women, however, some women in childbearing years may have a need for a SERM for some diagnoses. SERMs should not be used in women who are pregnant or breastfeeding as they have been shown to cause fetal harm. Patients typically need to be off of a SERM for an extended period of time prior to becoming pregnant.

Can children take selective estrogen receptor modulators?

There are no approved uses for SERMs in children.

Can seniors take selective estrogen receptor modulators?

Older adults can take SERMs, though there may be some situations where the use of SERMs is not recommended and may be high risk. Patients with cataracts must be careful and notify their doctor of any visual changes. If liver function is decreasing, dose adjustments may need to be made.

Are selective estrogen receptor modulators safe?

Recalls

There are currently no FDA recalls involving selective estrogen receptor modulators.

Restrictions

Do not take a selective estrogen receptor modulator if you have ever had an allergic reaction to any other SERM. 

SERMs have been linked to an increased risk of uterine cancer, liver cancer, stroke, or blood clots. These cancer types and conditions can be serious and fatal. Blood clots can lead to deep vein thrombosis (DVT) and pulmonary embolism (PE) which can be fatal thrombotic events.

If you have a history of hepatic (liver) disease, cataracts, stroke, blood clots, or high triglycerides (a type of lipid in the blood), you may not be a candidate for SERM therapy.

Before beginning SERM therapy, your doctor or healthcare provider may require a negative pregnancy test or cholesterol screening.

SERMs should not be taken with other hormone replacement therapy such as progesterone and estradiol as the effects of this combination have not been adequately studied. The antiestrogen effects of SERMs could be negated.

Patients who experience unexplained uterine or vaginal bleeding while on SERM therapy should have a clinical exam. SERMs are not linked to higher rates of proliferation in the endometrium than placebos, therefore it is important to look for other causes of the bleeding.

SERMs should not be used to lower cardiovascular risk. Studies have in fact shown that SERMs can increase the risk of cardiovascular events.

Are selective estrogen receptor modulators controlled substances?

No, selective estrogen receptor modulators are not controlled substances.

Common selective estrogen receptor modulators side effects

Serious adverse effects:

• Thromboembolism

• Stroke

• Endometrial cancer

• Endometrial hyperplasia

• Endometriosis

• Uterine sarcoma

• Uterine fibroids

• Ovarian cysts

• Erythema multiforme

• Stevens-Johnson syndrome

• Thrombocytopenia

• Leukopenia

• Hepatotoxicity

• Hepatic cancer

• Pancreatitis

• Interstitial pneumonitis

Common side effects:

• Hot flashes

• Edema

• Vaginal discharge

• Nausea

• Vomiting

• Menstrual irregularities

• Vaginal bleeding

• Weight changes

• Asthenia

• Pain

• Arthritis

• Upper respiratory infection

• Rash

• Mood disturbance

• Hypertension

This is not a complete list of common or serious side effects. Check the medication guide or with your healthcare provider for more side effects, warnings, and interactions.

How much do selective estrogen receptor modulators cost?

Osphena, the only SERM indicated for vaginal dryness, is relatively new on the market, and unfortunately, there is no generic. One month of treatment can cost over $300. Insurance coverage will vary by plan, but you may get a lower price with a SingleCare coupon for Osphena at participating pharmacies.

Nolvadex and Soltamox have been available generically as tamoxifen for quite some time. Brand name products can cost hundreds per month if not covered by insurance. Luckily a prescription for the generic is less than $13 when using a SingleCare coupon. Tamoxifen is an affordable and effective treatment. 

Your pharmacist can provide more information on each treatment option’s specific price without or without your insurance. Remember that SingleCare can save you up to 80% off of your cost on your prescriptions at participating pharmacies.