ER/estrogen-receptor; Clomiphene binds to muscarinic cholinergic receptors and calcium channel blocker binding sites in cell membranes [1]

In vitro activity: Clomifene competes with [3H]-QNB and [3H]-nitrendipine for their binding to the receptor in the membrane fractions from the urinary bladder and myometrium. Clomifene inhibits estrogen receptors in the hypothalamus, inhibiting negative feedback of estrogen on gonadotropinrelease, leading to up-regulation of the hypothalamic–pituitary–gonadal axis. Clomifene is a mixture of two geometric isomers, enclomifene (E-clomifene) and zuclomifene (Z-clomifene).

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In membrane preparations from various tissues, Clomiphene inhibits the binding of radiolabeled muscarinic ligands (e.g., quinuclidinyl benzilate) and calcium channel blockers (e.g., nitrendipine) to their respective binding sites. The inhibition is concentration-dependent, indicating competitive or non-competitive interaction with these sites [1]

Clomiphene citrate treatment significantly increases the chance of homosexuality and effeminized behavior in male mice.

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Perinatal treatment of male mice with Clomiphene (administered to pregnant mice at a dose of 100 μg/day from gestational day 12 to postnatal day 10) alters sexual orientation, as evidenced by changes in mating behavior and preference tests. Treated male mice show reduced preference for female mice compared to controls [2]
In clinical settings, Clomiphene is used for ovulation induction in women with anovulatory infertility. It stimulates follicle-stimulating hormone (FSH) and luteinizing hormone (LH) release from the pituitary, leading to follicular development and ovulation. Ovulation rates of 70-80% are reported, with pregnancy rates of 30-40% [3]

Membrane fractions from tissues (e.g., brain, heart) are prepared and incubated with radiolabeled muscarinic ligands or calcium channel blockers in the presence of varying concentrations of Clomiphene. After incubation, bound and free radioligands are separated by filtration or centrifugation. The amount of bound radioligand is measured, and inhibition curves are generated to assess the interaction of Clomiphene with the binding sites [1]

For perinatal studies, pregnant mice receive Clomiphene via subcutaneous injection at a dose of 100 μg/day from gestational day 12 to postnatal day 10. Control groups receive vehicle injections. Offspring male mice are tested for sexual orientation using behavioral assays (e.g., preference for female mice vs. male mice) after reaching adulthood [2]

Absorption, Distribution and Excretion
Based on early studies with 14 C-labeled clomifene, the drug was shown to be readily absorbed orally in humans.
Based on early studies with 14C-labeled clomiphene citrate, the drug was shown to be readily absorbed orally in humans and excreted principally in the feces. Mean urinary excretion was approximately 8% with fecal excretion of about 42%.
SC DOSE OF (14)C CLOMIPHENE CITRATE...WAS DISTRIBUTED IN TISSUES OF FEMALE GUINEA PIG NEONATES... ESTROGENIC-RESPONSIVE TISSUES SHOWED HIGH AFFINITY FOR (14)C. LEVELS OF (14)C...CONSTANT IN UTERUS...THOSE IN OVARIES & PLASMA DECLINED...IN ADRENALS INCR. /CLOMIPHENE CITRATE/
ABOUT ONE-HALF OF THE INGESTED DOSE IS EXCRETED IN FIVE DAYS; TRACES APPEAR IN THE FECES UP TO SIX WEEKS AFTER ADMIN. /CLOMIPHENE CITRATE/
Clomiphene is well absorbed following oral administration. The drug and its metabolites are eliminated primarily in the feces and to a lesser extent in the urine. The rather long plasma half-life (approximately 5 to 7 days) is due largely to plasma protein binding, enterophepatic circulation, and accumulation in fatty tissues. Active metabolites with long half-lives also may be produced.

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Metabolism / Metabolites
Hepatic
INCUBATION OF THE NONSTEROIDAL ANTIESTROGEN CLOMIPHENE WITH RAT LIVER MICROSOMES RESULTED IN THE FORMATION OF THE 4-HYDROXY-, N-DESETHYL-, & N-OXIDE METABOLITES, IN QUALITATIVE CONTRAST TO RESULTS PREVIOUSLY OBTAINED ANALOGOUSLY WITH RABBIT MICROSOMES IN WHICH ONLY THE FIRST 2 METABOLITES WERE DETECTED. ORAL ADMIN OF CLOMIPHENE RESULTED IN NO DETECTABLE URINARY ELIMINATION OF THE DRUG OR ITS METABOLITES. 4-HYDROXYCLOMIPHENE WAS THE SOLE DETECTABLE ELIMINATION PRODUCT IN FECAL EXTRACTIONS.
Hepatic

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Biological Half-Life
5-7 days

60974 women TDLo oral 5 mg/kg/5D-I SENSE ORGANS AND SPECIAL SENSES: VISUAL FIELD CHANGES: EYE; ENDOCRINE: TUMORS Postgraduate Medical Journal., 72(172), 1996 [PMID:8731710]
60974 rat LD50 oral 5750 mg/kg Toxicology and Applied Pharmacology., 9(44), 1966 [PMID:5967566]
60974 rat LD50 intraperitoneal 530 mg/kg Toxicology and Applied Pharmacology., 9(44), 1966 [PMID:5967566]
60974 mouse LD50 oral 1400 mg/kg Pharmaceutical Chemistry Journal, 23(75), 1989

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Toxicity Summary
Clomifene has both estrogenic and anti-estrogenic properties, but its precise mechanism of action has not been determined. Clomifene appears to stumulate the release of gonadotropins, follicle-stimulating hormone (FSH), and leuteinizing hormone (LH), which leads to the development and maturation of ovarian follicle, ovulation, and subsequent development and function of the coprus luteum, thus resulting in pregnancy. Gonadotropin release may result from direct stimulation of the hypothalamic-pituitary axis or from a decreased inhibitory influence of estrogens on the hypothalamic-pituitary axis by competing with the endogenous estrogens of the uterus, pituitary, or hypothalamus. Clomifene has no apparent progestational, androgenic, or antrandrogenic effects and does not appear to interfere with pituitary-adrenal or pituitary-thyroid function.

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Toxicity Data
The acute oral LD₅₀ of clomifene is 1700 mg/kg in mice and 5750 mg/kg in rats. The toxic dose in humans is not known. Toxic effects accompanying acute overdosage of clomifene have not been reported. Signs and symptoms of overdosage as a result of the use of more than the recommended dose during clomifene therapy include nausea, vomiting, vasomotor flushes, visual blurring, spots or flashes, scotomata, ovarian enlargement with pelvic or abdominal pain.

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Hepatotoxicity
There is little information on serum aminotransferase levels during clomiphene therapy which is typically given in low doses for a short time only. There have been a few reports of mild serum enzyme elevations in patients taking clomiphene, but no convincing instances of idiosyncratic, clinically apparent liver injury with its use.
Drugs used to treat infertility in women typically act by stimulation of the ovarian follicles which can lead to the ovarian hyperstimulation syndrome (OHSS), which can occasionally be accompanied by serum enzyme elevations and even jaundice. This syndrome typically arises within 4 to 14 days of ovarian stimulation with gonadotropins or clomiphene and is characterized by the onset of abdominal pain and distension with ascites and enlarged ovaries and ovarian cysts. There can be marked fluid shifts with hemoconcentration and rapid onset of severe ascites and pleural effusions. Liver tests are elevated in 25% to 40% of patients with OHSS, typically with mild-to-moderate increases in ALT and AST values, but minimal or no elevations in serum bilirubin and alkaline phosphatase levels. The liver test abnormalities resolve with resolution of the OHSS, usually within 2 to 3 weeks of onset. In severe instances, OHSS can be fatal, but death is usually due to dehydration, shock and septicemia rather than hepatic failure. In typical cases with abnormal liver enzymes, liver histology reveals nonspecific changes of sinusoidal dilatation, mild fat accumulation and focal inflammatory infiltrates with macrophages and lymphocytes. OHSS is less common with clomiphene than with human chorionic gonadotropin (hCG) induction of ovulation.
Likelihood score: C (probable cause of clinically apparent liver injury as a part of the ovarian hyperstimulation syndrome).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Clomiphene appeared in low amounts in milk in one woman. Several studies found that clomiphene suppresses lactation in women who did not want to breastfeed. It appears to act by lowering serum prolactin, especially the post-stimulation surge in serum prolactin. It is likely that clomiphene would interfere with lactation in a nursing mother.
◉ Effects in Breastfed Infants
A woman who was taking clomiphene in a dose of 2.04 mg/kg daily partially breastfed her infant. She did not observe any adverse effects in her infant.
◉ Effects on Lactation and Breastmilk
A double-blind study compared clomiphene in dosages of 50 mg daily for 10 days (n = 110), 100 mg daily for 5 days (n = 26) and placebo (n = 41) in their ability to suppress lactation and relieve pain and engorgement in nonnursing postpartum mothers. Both dosages of clomiphene were superior to placebo as reported by the women, but the 100 mg daily dosage was somewhat superior to the 50 mg daily dosage.
A study compared clomiphene 100 mg daily for 5 days (n = 60) to placebo (n = 30) in suppressing lactation and symptoms of engorgement. Starting clomiphene within 12 hours of delivery was more effective in all measures than starting it 12 hours or more after delivery as judged by a physician observer; both treatments were more effective than mechanical measures alone such as breast binding.
A randomized trial compared clomiphene 50 mg twice daily for 14 days (n = 15) to bromocriptine 2.5 mg twice daily for 14 days (n = 15), diethylstilbestrol 5 mg 3 times daily for 14 days (n = 15), testosterone propionate 75 mg intramuscularly once (n = 15), and placebo 3 times daily by mouth (n = 15) in their ability to reduce serum prolactin and lactation postpartum. After three days of treatment, serum prolactin was reduced to 65% of baseline by clomiphene compared to a drop to 35% in patients who received bromocriptine. Clomiphene was also less effective than bromocriptine in suppressing lactation and symptoms of engorgement.
A study compared clomiphene 100 mg daily for 7 days (n = 10) to placebo (n = 12) started on the first day postpartum. Clomiphene was no more effective than placebo in suppressing lactation or reducing serum prolactin concentrations.
Women in the first week postpartum who did not wish to breastfeed received either clomiphene 50 mg twice daily (n = 10) or placebo (n = 10). Women who received clomiphene did not experience a rise in serum prolactin from baseline values during use of a breast pump; those given placebo had the normal post-stimulation rise in serum prolactin.
Eighty postpartum women were studied. Forty received clomiphene 50 mg twice daily for 5 days beginning the first day postpartum; 20 received clomiphene 50 mg twice daily for 5 days beginning the fourth day postpartum; and, 20 received placebo. All women receiving clomiphene experienced inhibition of lactation, and reductions in breast engorgement, discomfort and serum prolactin. Prolactin serum concentrations became statistically lower than baseline on day 3 for the women who were 1 day postpartum and on day 5 for those who were 4 days postpartum at the outset. Placebo did not suppress lactation nor suppress serum prolactin.

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Adverse Effects
Some reported adverse effects from using clomiphene include headache, dizziness, exacerbation of psychiatric illnesses, gynecomastia, testicular tumor, vasomotor flushing, gastrointestinal disturbance, and mastalgia. Other common adverse reactions are nausea, vomiting, ovarian enlargement, blurred vision, scintillating scotoma, abnormal uterine bleeding, pelvic pain, and hypertriglyceridemia. Some serious reactions to the use of clomiphene are multiple pregnancies, thrombocytopenia, pancreatitis, risk of ovarian cancer after prolonged use, increased risk of malignant melanoma, severe visual disturbance, and hepatic damage.
Ovarian hyperstimulation syndrome (OHSS) is reported in patients using clomiphene citrate therapy for ovulation induction. OHSS can progress rapidly (within 24 hours) and become a medical emergency.

[1]. Interaction of antiestrogens with binding sites for muscarinic cholinergic drugs and calcium channel blockers in cell membranes. Cancer Chemother Pharmacol. 1990;26(4):310-2;
[2]. [Perinatal clomiphene citrate treatment changes sexual orientations of male mice]. Dongwuxue Yanjiu. 2013 Oct;34(5):487-92.
[3]. Ovulation induction with clomifene: a primary care perspective. J Fam Plann Reprod Health Care. 2012;38(1):48-52.

Clomiphene Citrate can cause cancer and developmental toxicity according to state or federal government labeling requirements.
Zuclomiphene Citrate is the cis isomer of clomiphene which exhibits weak estrogen agonist activity evaluated for antineoplastic activity against breast cancer. (NCI04)
Clomiphene Citrate is the citrate salt form of clomiphene, a triphenylethylene nonsteroidal ovulatory stimulant evaluated for antineoplastic activity against breast cancer. Clomiphene has both estrogenic and anti-estrogenic activities that compete with estrogen for binding at estrogen receptor sites in target tissues. This agent causes the release of the pituitary gonadotropins follicle stimulating hormone (FSH) and luteinizing hormone (LH), leading to ovulation. (NCI04)
A triphenyl ethylene stilbene derivative which is an estrogen agonist or antagonist depending on the target tissue. Note that ENCLOMIPHENE and ZUCLOMIPHENE are the (E) and (Z) isomers of Clomiphene respectively.
See also: Clomiphene Citrate (annotation moved to).

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Clomiphene is a triphenylethylene derivative with anti-estrogenic properties, commonly used in reproductive medicine. Its ability to interact with muscarinic receptors and calcium channel binding sites suggests potential off-target effects beyond its primary role in ovulation induction [1] [3]

C26H28CLNO.C6H8O7

598.08

597.212

C, 64.26; H, 6.07; Cl, 5.93; N, 2.34; O, 21.40

50-41-9

Clomifene;911-45-5;Clomifene hydrochloride;57049-00-0

3033832

White to off-white solid powder

509ºC at 760 mmHg

116.5-118°C

261.6ºC

5.314

4

9

14

42

708

0

CCN(CC)CCOC1=CC=C(C=C1)/C(=C(/C2=CC=CC=C2)\Cl)/C3=CC=CC=C3.C(C(=O)O)C(CC(=O)O)(C(=O)O)O

PYTMYKVIJXPNBD-OQKDUQJOSA-N

InChI=1S/C26H28ClNO.C6H8O7/c1-3-28(4-2)19-20-29-24-17-15-22(16-18-24)25(21-11-7-5-8-12-21)26(27)23-13-9-6-10-14-23;7-3(8)1-6(13,5(11)12)2-4(9)10/h5-18H,3-4,19-20H2,1-2H3;13H,1-2H2,(H,7,8)(H,9,10)(H,11,12)/b26-25-;

2-[4-[(Z)-2-chloro-1,2-diphenylethenyl]phenoxy]-N,N-diethylethanamine;2-hydroxypropane-1,2,3-tricarboxylic acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.5 mg/mL (4.18 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (4.18 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (4.18 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 7.14 mg/mL (11.94 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication (<60°C).

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 (Please use freshly prepared in vivo formulations for optimal results.)