Enclomiphene is the trans-isomer of clomiphene citrate. Commercial clomiphene contains approximately 62% zuclomiphene (cis, weak ER agonist, long half-life) and 38% enclomiphene (trans, pure ER antagonist, shorter half-life). Enclomiphene as an isolated isomer provides pure hypothalamic ER blockade without the weak agonist activity of zuclomiphene. This results in cleaner LH/FSH stimulation, faster clearance, and no accumulation of the agonist component — addressing the main pharmacological limitations of racemic clomiphene.
Also Known As
Trans-clomiphene, Androxal, Enclomifene
Compound Class
Selective Oestrogen Receptor Modulator (SERM) — pure ER antagonist
Molecular Formula
C₂₆H₂₈ClNO
Molecular Weight
406.0 Da
CAS Number
15690-57-0
Half-Life
~10 hours (shorter than clomiphene)
Research Applications
Pure Hypothalamic ER Antagonism
Enclomiphene isolates the ER antagonist isomer of clomiphene. Research comparing enclomiphene vs racemic clomiphene vs zuclomiphene characterises which isomer drives the HPG axis stimulation and which contributes to visual and oestrogen agonist adverse effects.
Secondary Hypogonadism — Isomer Comparison
Phase 2/3 RCTs (Repros Therapeutics): enclomiphene 12.5–25mg in men with secondary hypogonadism. Testosterone normalisation comparable to clomiphene but with cleaner hormonal profile and shorter washout. Sperm count maintained (unlike exogenous TRT).
Fertility-Preserving Testosterone Restoration
Unlike injectable testosterone which suppresses HPG axis, enclomiphene stimulates endogenous production. Research models: comparison with TRT for testosterone elevation while maintaining fertility endpoints. Spermatogenesis maintained at comparable rates to baseline.
Isomer Pharmacokinetics Research
Enclomiphene t½ ~10h vs zuclomiphene t½ ~30h. PK research: once-daily dosing achieves rapid steady-state without accumulation. Relevant for developing cleaner SERM-based HPG stimulation protocols in research models.
Key Research Data
Study / Source
Key Findings
Kim et al. 2013 J Urol (Androxal)
Phase 2: enclomiphene vs TRT — both raised testosterone, enclomiphene maintained sperm count vs suppression with TRT
Wiehle et al. 2014 Curr Med Res Opin
Phase 3: enclomiphene 12.5–25mg in 125 hypogonadal men — testosterone normalised, LH/FSH maintained
Isomer PK comparison
Enclomiphene vs zuclomiphene separate administration: trans-isomer responsible for HPG stimulation, cis-isomer responsible for agonist activity and accumulation
Specifications
Format
Oral tablet — 25mg per tablet
Purity
≥99% HPLC
Identity
MS confirmed — trans-isomer confirmed
Storage
Room temperature, protect from light
Isomer purity
Trans-enclomiphene >98% (free of zuclomiphene)
Frequently Asked Questions
What is Enclomiphene (Trans-Clomiphene)?
Enclomiphene (Trans-Clomiphene) is a Selective Oestrogen Receptor Modulator (SERM) — pure ER antagonist. Enclomiphene is the trans-isomer of clomiphene citrate. Commercial clomiphene contains approximately 62% zuclomiphene (cis, weak ER agonist, long half-life) and 38% enclomiphene (trans, pure ER antagonist, shorter half-life). Enclomiphene as an isola…
How does Enclomiphene work in research models?
Enclomiphene isolates the ER antagonist isomer of clomiphene. Research comparing enclomiphene vs racemic clomiphene vs zuclomiphene characterises which isomer drives the HPG axis stimulation and which contributes to visual and oestrogen agonist adverse effects….
What makes Enclomiphene different from similar compounds?
Phase 2/3 RCTs (Repros Therapeutics): enclomiphene 12.5–25mg in men with secondary hypogonadism. Testosterone normalisation comparable to clomiphene but with cleaner hormonal profile and shorter washout. Sperm count maintained (unlike exogenous TRT)….
Does QSC ship Enclomiphene to the USA?
Yes. QSC Enclomiphene ships domestically across the USA and internationally to EU, UK, Canada, and Australia. Every batch carries a Janoshik third-party COA confirming ≥99% HPLC purity and MS identity verification.
