Enclomiphene

Enclomiphene is the trans isomer of clomiphene and an oral selective estrogen-receptor modulator studied in men with secondary hypogonadism. Its strongest results are hormone and sperm surrogate endpoints.

tier B · libido · 4 to 8 FDA advisory vote against 503A listing

verdict

Oral enclomiphene can raise endogenous testosterone, LH, and FSH while maintaining sperm concentration over a short trial. It has not established symptom relief, fertility or live-birth benefit, or an approved long-term treatment role.

the core tension

The endocrine signal is consistent and biologically coherent. The approval record shows why raising testosterone and preserving sperm concentration were not enough: the program did not establish a clinical benefit that mattered to patients.

what it is

Enclomiphene is the trans isomer of clomiphene and a nonsteroidal selective estrogen-receptor modulator. The identity on this page is the base; trial products commonly used enclomiphene citrate.

what it does

By antagonizing estrogen feedback at the hypothalamic-pituitary axis, the studied oral product increased LH and FSH, which was accompanied by higher endogenous testosterone and maintained sperm concentration in men with secondary hypogonadism.

origin

The sponsor submitted a US application in 2015 and later reported a complete response letter. EMA refused the EnCyzix application in 2018, and FDA's 2022 compounding advisory review again emphasized the clinical-efficacy gap.

does it work

It works on the measured hormone and semen surrogates in the studied men. The reviewed program did not show that those changes improve libido, impotence, bone strength, body weight, fertility, or live birth.

key facts

• molecular formula: C26H28ClNO (enclomiphene base)
• molecular weight: 406.0 g/mol (enclomiphene base)
• amino acids: n/a (small-molecule SERM, not a peptide)
• half-life: not stated here; no source-backed value is transferred across base, citrate, or compounded products
• type: trans-clomiphene isomer; nonsteroidal selective estrogen-receptor modulator
• CAS: 15690-57-0
• 588 participants across four main studies submitted to EMA
• 499 participants in the open-label registered safety study
• 0 approved FDA or EMA enclomiphene products in the reviewed record

frequently asked questions

Is enclomiphene FDA approved?

No. The sponsor reported an FDA complete response letter, and FDA later reviewed the substance in a compounding-policy context rather than as an approved drug.

Was it approved in Europe?

No. EMA refused marketing authorization for EnCyzix in 2018.

What did the trials actually show?

They showed changes in testosterone, LH, FSH, and sperm concentration. Those are surrogate endpoints, not direct proof of symptom relief or fertility.

Does maintained sperm concentration prove a fertility benefit?

No. The cited studies did not establish pregnancy or live-birth outcomes.

What is the human half-life?

This page does not publish a numeric half-life. The reviewed records do not provide a value that can be safely transferred across enclomiphene base, citrate products, and unapproved compounded formulations.

related peptides

• testosterone: the topical comparator in the phase 3 surrogate-endpoint trials

reptides grades the research record and cites the literature behind every call. research reference only; not medical advice.