Clomiphene Citrate
Mixed SERM used to stimulate endogenous gonadotropin release
Mechanism of Action
Clomiphene is a triphenylethylene SERM consisting of two stereoisomers (zuclomiphene and enclomiphene). It acts as a competitive antagonist at hypothalamic estrogen receptors, blocking negative feedback of circulating estradiol on the hypothalamic-pituitary axis. This disinhibition increases gonadotropin-releasing hormone (GnRH) pulsatility, stimulating pituitary LH and FSH release, which in turn stimulates gonadal steroidogenesis and spermatogenesis. Enclomiphene (trans-isomer) is the more active isomer for ovulation induction. In research contexts, clomiphene is studied for post-cycle HPTA recovery and hypogonadism.
Evidence Level
Clinical Trial - Human
4 studies published
Pharmacology
Molecular Weight
405.9 g/mol (free base); 598.1 g/mol (citrate)
Half-Life
Approximately 5 days (parent); enclomiphene half-life ~10 hours
Bioavailability
Oral bioavailability well-established but not precisely quantified