Enclomiphene vs Anastrozole: Drug Comparison

Enclomiphene is a non-steroidal selective estrogen receptor modulator (SERM) sometimes used to treat male secondary hypogonadism, or low testosterone caused by problems with the hypothalamus or pituitary gland. The medication is derived from another SERM called clomiphene citrate, and while enclomiphene is not approved by the United States Food and Drug Administration (FDA) to treat any condition on its own, it is available through compounding pharmacies.

Enclomiphene is designed to stimulate testosterone production while minimizing the estrogenic side effects sometimes seen with clomiphene, such as breast tissue growth. It works by blocking estrogen signals in the brain, which increases the release of certain hormones, like luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones then tell the testicles to produce more natural testosterone.

Enclomiphene is taken as a daily pill, usually in doses of 12.5 milligrams (mg) to 25 mg.

Enclomiphene boosts testosterone while helping the body maintain its natural hormone production and sperm count, making it a good alternative to traditional testosterone replacement therapies for men who want to preserve their fertility.

Anastrozole is an oral medication used to lower estrogen levels, primarily prescribed for breast cancer in women. It is also sometimes prescribed off-label in men to address hormone-related issues such as low testosterone, gynecomastia (breast growth), and certain cases of infertility.

Belonging to a class of drugs known as aromatase inhibitors, anastrozole blocks the enzyme that converts androgens into estrogen.

Reducing estrogen production can help restore a healthier balance of testosterone in the body.

Selective estrogen receptor modulator

Aromatase inhibitor

Enclomiphene is not approved as a drug in the United States

Anastrozole is indicated for:

• Adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer

• First-line treatment of postmenopausal women with hormone receptor-positive or hormone receptor unknown locally advanced or metastatic breast cancer

• Treatment of advanced breast cancer in postmenopausal women with disease progression following tamoxifen therapy

• Typically taken orally

• Often prescribed at 6.25 mg, 12.5 mg, and 25 mg doses

• Typically taken orally once daily

• Comes in 1 mg tablets

Information about enclomiphene is limited

In the early breast cancer (ATAC) study, the most common (occurring with an incidence of ≥10%) side effects occurring in women taking anastrozole tablets included:

• Hot flashes

• Weakness

• Arthritis

• Pain

• Joint pain

• Inflammation of the throat

• High blood pressure

• Depression

• Nausea and vomiting

• Rash

• Osteoporosis

• Fractures

• Back pain

• Insomnia

• Headache

• Peripheral swelling and lymphedema, regardless of causality

In the advanced breast cancer studies, the most common (occurring with an incidence of >10%) side effects occurring in women taking anastrozole tablets included:

• Hot flashes

• Nausea

• Weakness

• Pain

• Headache

• Back pain

• Bone pain

• Increased cough

• Shortness of breath

• Inflammation of the throat

• Peripheral swelling

Information about enclomiphene is limited

• Patients with demonstrated hypersensitivity to anastrozole tablets or any excipient

• Drug interactions: Tamoxifen, estrogen-containing products

Information about enclomiphene is limited

• In women with pre-existing ischemic heart disease, an increased incidence of ischemic cardiovascular events occurred with anastrozole tablets use compared to tamoxifen use

• Decreases in bone mineral density may occur

• Increases in total cholesterol may occur

• Embryo-fetal toxicity: Anastrozole tablets may cause fetal harm

• Females and males of reproductive potential: Verify pregnancy status prior to initiation of anastrozole tablets

• Breastfeeding: Do not breastfeed

Information about enclomiphene is limited. It is the active isomer of clomiphene.

*This information is from the anastrozole label used by Avet Pharmaceuticals Inc. See the Full Prescribing Information for more complete information. Anastrozole may also be the active ingredient in other medications, and this information may not be accurate for all medications that include the active ingredient anastrozole.