Enclomiphene

Enclomiphene is a non-steroidal selective estrogen receptor modulator (SERM) and one of the two stereoisomers of the clomiphene molecule. It exists as an optical isomer separate from zuclomiphene. In medical practice, enclomiphene is studied primarily for its effects on the hypothalamic-pituitary-gonadal axis and is used in research on male hypogonadism and infertility. The drug is typically discussed in the context of enclomiphene citrate, the salt form used in clinical trials.

Enclomiphene acts as an estrogen receptor antagonist in the hypothalamus, reducing estrogen negative feedback and promoting release of gonadotropin-releasing hormone. This increases luteinizing hormone and follicle-stimulating hormone secretion, which can raise endogenous testosterone production in men and, in certain contexts, support ovulation induction in women treated with clomiphene derivatives. However, enclomiphene is not equivalent to the full clomiphene citrate preparation and its clinical efficacy depends on formulation and population.

Pharmacokinetics and formulation: when taken orally, enclomiphene is absorbed and undergoes hepatic metabolism with active metabolites; due to the nature of SERMs, it can have a relatively long duration of action and elimination may be prolonged. The exact pharmacokinetic profile varies with dosing and whether the drug is given as enclomiphene citrate.

Safety and regulatory status: common adverse effects seen with SERMs—such as hot flashes, headaches, nausea, and mood changes—may occur. Visual disturbances and rare thromboembolic events have been reported with clomiphene-type medications, though the incidence with enclomiphene specifically is not well defined. Enclomiphene has been under investigation, and it has not achieved widespread regulatory approval as a standalone product in all markets; clomiphene citrate remains the widely used, approved therapy for ovulation induction.