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 of clomiphene citrate labeled with 14C, this drug is readily absorbed orally in humans. Based on early studies of clomiphene citrate labeled with 14C, this drug is readily absorbed orally in humans and is primarily excreted via feces. The average urinary excretion rate is approximately 8%, and the fecal excretion rate is approximately 42%. Subcutaneous injection of clomiphene citrate labeled with 14C…distributed in the tissues of female newborn guinea pigs…estrogen-responsive tissues showed a high affinity for 14C. (14)C levels remained stable in the uterus…decreased in the ovaries and plasma…increased in the adrenal glands. /clomiphene citrate/ Approximately half of the ingested dose was excreted within five days; trace amounts of the drug remained in the feces for up to six weeks after administration. /Clomiphene Citrate/
Clomiphene is well absorbed after oral administration. The drug and its metabolites are primarily excreted in feces, with a small amount excreted in urine. The relatively long plasma half-life (approximately 5 to 7 days) is mainly due to plasma protein binding, enterohepatic circulation, and accumulation in adipose tissue. Long-lived active metabolites may also be produced.

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Metabolism/Metabolites
Liver
Incubation of the nonsteroidal anti-estrogenic clomiphene with rat liver microsomes resulted in the formation of 4-hydroxy, N-deethyl, and N-oxide metabolites, in stark contrast to previous similar experiments using rabbit microsomes, where only the first two metabolites were detected. No urinary excretion of the drug or its metabolites was detected after oral administration of clomiphene. 4-hydroxyclomiphene was the only detectable elimination product in the fecal extract.
Liver

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Biological Half-Life
5-7 days

60974 twomentTDLotoralt 5 mg/kg/5D-ItSENSE Organs and special senses: visual field changes: eye; endocrine: Journal of Postgraduate Oncology, 72(172), 1996 [PMID:8731710]
60974 tratt LD50 Oral 5750 mg/kg Toxicology and Applied Pharmacology, 9(44), 1966 [PMID:5967566]
60974 tratt LD50 Intraperitoneal 530 mg/kg Toxicology and Applied Pharmacology, 9(44), 1966 [PMID:5967566]
60974 t Mouse LD50 Oral 1400 mg/kg Journal of Medicinal Chemistry, 23(75), 1989

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Toxicity Overview
Clomiphene possesses both estrogenic and antiestrogenic properties, but its exact mechanism of action remains unclear. Clomiphene appears to stimulate the release of gonadotropins, including follicle-stimulating hormone (FSH) and luteinizing hormone (LH), thereby promoting the development and maturation of ovarian follicles, ovulation, and subsequent development and function of the corpus luteum, ultimately leading to pregnancy. The release of gonadotropins may be due to direct stimulation of the hypothalamic-pituitary axis, or it may be due to clomiphene competing with endogenous estrogens in the uterus, pituitary gland, or hypothalamus, thereby reducing the inhibitory effect of estrogen on the hypothalamic-pituitary axis. Clomiphene has no significant progesterone, androgen, or antiandrogen effects and does not appear to interfere with the function of the pituitary-adrenal axis or the pituitary-thyroid axis.

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Toxicity Data
The acute oral LD50 of clomiphene is 1700 mg/kg in mice and 5750 mg/kg in rats. The toxic dose in humans is unknown. There are no reports of acute overdose of clomiphene.
During treatment with clomiphene, if the dose exceeds the recommended dose, overdose symptoms may occur, including nausea, vomiting, vasomotor flushing, blurred vision, spots or flashes of light in front of the eyes, scotomas, enlarged ovaries, and pelvic or abdominal pain.

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Hepatotoxicity
Information on serum transaminase levels during clomiphene treatment is limited because clomiphene is usually taken only in low doses for short periods. Although there are a few reports of mild elevations in serum enzymes in patients taking clomiphene, there is no conclusive evidence that it causes specific, clinically significant liver damage.
Drugs used to treat female infertility often work by stimulating ovarian follicles, which can lead to ovarian hyperstimulation syndrome (OHSS), sometimes accompanied by elevated serum enzymes and even jaundice. This syndrome typically appears 4 to 14 days after ovarian stimulation with gonadotropins or clomiphene, and is characterized by abdominal pain, abdominal distension with ascites, enlarged ovaries, and ovarian cysts. Patients may experience significant fluid shifts, leading to hemoconcentration and rapid development of severe ascites and pleural effusion. Liver dysfunction is present in 25% to 40% of patients with ovarian hyperstimulation syndrome (OHSS), typically manifested as mild to moderate elevations in alanine aminotransferase (ALT) and aspartate aminotransferase (AST), but with minimal or no elevation in serum bilirubin and alkaline phosphatase levels. Liver dysfunction usually resolves as OHSS subsides, typically within 2 to 3 weeks of onset. In severe cases, OHSS can be fatal, but death is usually due to dehydration, shock, and sepsis, rather than liver failure. In typical cases of abnormal liver enzymes, liver histology shows nonspecific changes, including sinusoidal dilatation, mild fatty deposits, and focal inflammatory infiltration dominated by macrophages and lymphocytes. Compared to ovulation induced by human chorionic gonadotropin (hCG), the probability of ovarian hyperstimulation syndrome (OHSS) is lower with clomiphene use.
Probability Score: C (Possibly due to clinically significant liver damage in OHSS).
Effects during Pregnancy and Lactation
◉ Summary of Lactation Use
A small amount of clomiphene was detected in the breast milk of a woman. Multiple studies have found that clomiphene inhibits lactation in women who do not wish to breastfeed. Its mechanism of action appears to be by reducing serum prolactin levels, particularly the peak prolactin level after stimulation. Clomiphene may interfere with lactation in breastfeeding mothers.
◉ Effects on Breastfed Infants
A woman taking 2.04 mg/kg clomiphene daily breastfed part-time. No adverse reactions were observed in her infant.
◉ Effects on Lactation and Breast Milk
A double-blind study compared the effects of clomiphene daily at 50 mg for 10 days (n = 110), clomiphene daily at 100 mg for 5 days (n = 26), and placebo (n = 41) on inhibiting lactation and relieving pain and breast engorgement in non-lactating postpartum mothers. According to women's reports, both doses of clomiphene were superior to placebo, but the 100 mg daily dose was slightly superior to the 50 mg daily dose.
A study compared the effects of clomiphene daily at 100 mg (n = 60) for 5 days with placebo (n = 30) on inhibiting lactation and relieving breast engorgement symptoms. Physicians observed that starting clomiphene within 12 hours postpartum was superior to starting clomiphene at 12 hours or longer postpartum in all indicators; both treatments were more effective than mechanical measures alone (e.g., breast binding). A randomized trial compared the effects of four treatment regimens on reducing postpartum serum prolactin levels and decreasing lactation: clomiphene 50 mg twice daily for 14 days (n = 15); bromocriptine 2.5 mg twice daily for 14 days (n = 15); diethylstilbestrol 5 mg three times daily for 14 days (n = 15); testosterone propionate 75 mg intramuscularly once (n = 15); and placebo orally three times daily (n = 15). After three days of treatment, serum prolactin levels in the clomiphene group decreased to 65% of baseline, while those in the bromocriptine group decreased to only 35%. Clomiphene was also less effective than bromocriptine in suppressing lactation and relieving breast engorgement. Another study compared the effects of starting clomiphene 100 mg/day on the first postpartum day for 7 days (n = 10) with placebo (n = 12). The results showed that clomiphene was no more effective than placebo in suppressing lactation or lowering serum prolactin levels. Women who did not wish to breastfeed during the first week postpartum were either treated with clomiphene 50 mg/day twice daily (n=10) or a placebo (n=10). Women taking clomiphene did not experience elevated serum prolactin levels above baseline during breast pump use; women taking the placebo experienced normal post-stimulation increases in serum prolactin. A total of 80 postpartum women participated in the study. Forty women took clomiphene 50 mg/day twice daily for five consecutive days starting from day one postpartum; 20 women took clomiphene 50 mg twice daily for five consecutive days starting from day four postpartum; and the remaining 20 women received a placebo. All women taking clomiphene experienced lactation suppression, breast engorgement, discomfort, and decreased serum prolactin levels. For subjects 1 day postpartum, serum prolactin concentrations were significantly lower than baseline levels on day 3; for subjects 4 days postpartum, serum prolactin concentrations were significantly lower than baseline levels on day 5. Placebo did not suppress lactation or lower serum prolactin levels. Adverse Reactions: Some reported adverse reactions to clomiphene include headache, dizziness, exacerbation of psychiatric illness, gynecomastia, testicular tumors, vasomotor flushing, gastrointestinal discomfort, and breast pain. Other common adverse reactions include nausea, vomiting, ovarian enlargement, blurred vision, scotoma, abnormal uterine bleeding, pelvic pain, and hypertriglyceridemia. Some serious adverse reactions to clomiphene include multiple pregnancy, thrombocytopenia, pancreatitis, increased risk of ovarian cancer with long-term use, increased risk of malignant melanoma, severe visual impairment, and liver damage. Ovarian hyperstimulation syndrome (OHSS) has been reported in patients treated with clomiphene citrate for ovulation induction. OHSS can progress rapidly (within 24 hours) and may develop into 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.

According to state or federal labeling requirements, clomiphene citrate may be carcinogenic and developmentally toxic. Clomiphene citrate is the cis isomer of clomiphene, possessing weak estrogen agonist activity and has been evaluated for antitumor activity against breast cancer. (NCI04) Clomiphene citrate is the citrate form of clomiphene, a stilbene-based nonsteroidal ovulation-inducing drug that has been evaluated for antitumor activity against breast cancer. Clomiphene has dual estrogenic and antiestrogenic activity, competitively binding to estrogen receptors in target tissues. The drug induces the pituitary gland to release gonadotropins follicle-stimulating hormone (FSH) and luteinizing hormone (LH), leading to ovulation. (NCI04) Clomiphene is a stilbene-based derivative that can act as either an estrogen agonist or an estrogen antagonist, depending on the target tissue. Please note that enclomiphene and clomiphene are the (E) and (Z) isomers of clomiphene, respectively.
See also: clomiphene citrate (note moved here).

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Clomiphene is a triphenylene derivative with anti-estrogenic properties, commonly used in reproductive medicine. Its ability to interact with muscarinic receptors and calcium channel binding sites suggests that there may be other potential off-target effects in addition to its primary role in inducing ovulation [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.)