Enclomiphene

Key points

• Enclomiphene is the trans (E) isomer of clomiphene citrate, a selective oestrogen receptor modulator that blocks oestrogenic suppression of the HPG axis to raise LH, FSH and testosterone.
• Clomiphene citrate, the parent mixture containing enclomiphene, is contraindicated in pregnancy and liver disease, and may cause visual disturbances including blurring and spots.
• The EMA’s CHMP issued a negative opinion for EnCyzix (enclomifene citrate) in January 2018, declining marketing authorisation.

Common questions about Enclomiphene

What separates Enclomisign from Androxal?

Both contain 50 mg enclomiphene citrate in tablet form and are listed for secondary hypogonadism. Androxal was developed by Repros Therapeutics; Enclomisign is marketed by Signature Pharma. They sit in the Hormone Therapy category and share the same active ingredient and strength, so the distinction is the brand and marketer rather than the medicine itself.

How does enclomiphene differ from Clomid?

Clomid is clomiphene citrate, a mixture of two geometric isomers: cis (zuclomiphene) and trans (enclomiphene), with the cis component making up 30% to 50% of the blend. Enclomiphene is the trans component isolated on its own. Some data suggest the cis isomer carries greater oestrogenic activity than the trans, so enclomiphene as a standalone molecule is designed to raise testosterone with less oestrogenic effect than the full mixture.

Further reading

• Assessment report - EMA
• Clomid - accessdata.fda.gov
• Testosterone Deficiency Guideline - American Urological Association