Clomifene

Not to be confused with clonidine or Klonopin.

Clomifene

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Systematic (IUPAC) name
2-(4-(2-chloro-1,2-diphenylethenyl) phenoxy)-N,N-diethyl-ethanamine
Clinical data
Pregnancy category	B3 (Au), X (U.S.)
Routes of administration	50 mg tablets
Legal status
Legal status	S4 (Au), POM (UK), ℞-only (U.S.)
Pharmacokinetic data
Bioavailability	High (>90%)
Metabolism	Hepatic (with enterohepatic circulation)
Biological half-life	5-7 days
Excretion	Mainly renal, some biliary
Identifiers
CAS Number	911-45-5
ATC code	G03GB02 (WHO)
PubChem	CID 1548953
DrugBank	APRD00880
ChemSpider	1265967
Chemical data
Formula	C26H28ClNO
Molar mass	406 or 598.10 (with citrate)[[]]
(verify)

Clomifene (INN) or clomiphene (USAN and former BAN) or Clomid or Clomifert is a selective estrogen receptor modulator (SERM) that increases production of gonadotropins by inhibiting negative feedback on the hypothalamus. It is used mainly for ovarian stimulation in female infertility due to anovulation (e.g., due to polycystic ovary syndrome). Clomiphene citrate is marketed under various trade names including Clomid, Serophene, and Milophene.

Mode of action

In normal physiologic female hormonal cycling, at 7 days past ovulation, high levels of estrogen and progesterone cause negative feedback inhibition at the hypothalamus and anterior pituitary. As a result, decreased LH levels leads to atrophy of the corpus luteum, subsequently leading to decreased production of estrogen and progesterone. This will release the feedback inhibition of the hypothalamus and anterior pituitary, causing the FSH level to rise again at day 22.

Therapeutically, clomiphene is given at day 2 of menses. By that time, FSH level is rising steadily, causing development of a few follicles. Follicles in turn produce the estrogen, which circulates in serum. Clomiphene acts by inhibiting the action of estrogen on the pituitary. Zuclomifene, the more active isomer (see below), binds to estrogen receptors and stays bound for long periods of time. This prevents normal receptor recycling and causes an effective reduction in hypothalamic estrogen receptor number. As a result, the body perceives a low level of estrogen, similar to day 22 in the previous cycle. Since estrogen can no longer effectively exert negative feedback on the hypothalamus, GnRH secretion becomes more pulsatile, which results in increased pituitary gonadotropin (FSH, LH) release. Increased FSH level causes growth of more ovarian follicles, and subsequently rupture of follicles resulting in ovulation.

Chemistry

Clomifene is a mixture of two geometric isomers, enclomifene (E-clomifene) and zuclomifene (Z-clomifene).

File:Enclomifene.png Enclomifene

File:Zuclomifene.png Zuclomifene

Adverse effects

Common adverse drug reactions associated with the use of clomifene (≥1% of patients) include: vasomotor flushes (or hot flashes ), abdominal discomfort, visual blurring (dose-dependent), and/or reversible ovarian enlargement and cyst formation. Infrequent adverse effects (0.1–1% of patients) include: abnormal uterine bleeding, nausea, and/or vomiting. Rare adverse effects (<0.1% of patients) include: reversible alopecia and/or ovarian hyperstimulation syndrome.

Clomiphene can lead to multiple ovulation, hence increasing the chance of twins (10% of births instead of the normal ~1%). In comparison to treatment with purified FSH, the rate of ovarian hyperstimulation syndrome is low. There may be an increased risk of ovarian cancer and weight gain. Some patients may experience vivid and/or disturbing dreams.

Illegal use in bodybuilding and other sports

Clomifene is commonly used by male anabolic steroid users to bind the estrogen receptors in their bodies, thereby blocking the effects of estrogen, such as gynecomastia. It also restores the body's natural production of testosterone. It is commonly used as a "recovery drug" and taken toward the end of a steroid cycle. It is included on the World Anti-Doping Agency list of illegal doping agents in sport. Some users report that taking Clomid increases the amount of fluid produced during ejaculation, which make it a fertility drug option for men as well.

External links

• Clomifene for conception; a pre-pregnancy site

de:Clomifen pt:Clomifeno