Clinical data | |
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Trade names | Tace, Estregur, Anisene, Clorotrisin, Merbentyl, Triagen, others |
Other names | CTA; Trianisylchloroethylene; tri-p-Anisylchloroethylene; TACE; tris(p-Methoxyphenyl)-chloroethylene; NSC-10108 |
AHFS/Drugs.com | Multum Consumer Information |
Routes of administration | By mouth [1] [2] |
Drug class | Nonsteroidal estrogen |
ATC code | |
Pharmacokinetic data | |
Metabolism | Mono-O-demethylation (liver CYP450) [3] [4] |
Metabolites | Desmethylchlorotrianisene [3] [4] |
Identifiers | |
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CAS Number | |
PubChem CID | |
IUPHAR/BPS | |
DrugBank | |
ChemSpider | |
UNII | |
KEGG | |
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ChEMBL | |
CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.008.472 |
Chemical and physical data | |
Formula | C23H21ClO3 |
Molar mass | 380.87 g·mol−1 |
3D model (JSmol) | |
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Chlorotrianisene (CTA), also known as tri-p-anisylchloroethylene (TACE) and sold under the brand name Tace among others, is a nonsteroidal estrogen related to diethylstilbestrol (DES) which was previously used in the treatment of menopausal symptoms and estrogen deficiency in women and prostate cancer in men, among other indications, but has since been discontinued and is now no longer available. [5] [6] [7] [1] [8] It is taken by mouth. [1] [2]
CTA is an estrogen, or an agonist of the estrogen receptors, the biological target of estrogens like estradiol. [7] [1] [9] [10] It is a high-efficacy partial estrogen and shows some properties of a selective estrogen receptor modulator, with predominantly estrogenic activity but also some antiestrogenic activity. [11] [12] CTA itself is inactive and is a prodrug in the body. [2] [13]
CTA was introduced for medical use in 1952. [14] It has been marketed in the United States and Europe. [14] [6] However, it has since been discontinued and is no longer available in any country. [1] [15]
CTA has been used in the treatment of menopausal symptoms and estrogen deficiency in women and prostate cancer in men, among other indications. [7] [1] It has been used to suppress lactation in women. [16] CTA has been used in the treatment of acne as well. [17] [18] [19]
Route/form | Estrogen | Dosage | |
---|---|---|---|
Oral | Estradiol | 1–2 mg 3x/day | |
Conjugated estrogens | 1.25–2.5 mg 3x/day | ||
Ethinylestradiol | 0.15–3 mg/day | ||
Ethinylestradiol sulfonate | 1–2 mg 1x/week | ||
Diethylstilbestrol | 1–3 mg/day | ||
Dienestrol | 5 mg/day | ||
Hexestrol | 5 mg/day | ||
Fosfestrol | 100–480 mg 1–3x/day | ||
Chlorotrianisene | 12–48 mg/day | ||
Quadrosilan | 900 mg/day | ||
Estramustine phosphate | 140–1400 mg/day | ||
Transdermal patch | Estradiol | 2–6x 100 μg/day Scrotal: 1x 100 μg/day | |
IM or SC injection | Estradiol benzoate | 1.66 mg 3x/week | |
Estradiol dipropionate | 5 mg 1x/week | ||
Estradiol valerate | 10–40 mg 1x/1–2 weeks | ||
Estradiol undecylate | 100 mg 1x/4 weeks | ||
Polyestradiol phosphate | Alone: 160–320 mg 1x/4 weeks With oral EE: 40–80 mg 1x/4 weeks | ||
Estrone | 2–4 mg 2–3x/week | ||
IV injection | Fosfestrol | 300–1200 mg 1–7x/week | |
Estramustine phosphate | 240–450 mg/day | ||
Note: Dosages are not necessarily equivalent. Sources: See template. |
In men, CTA can produce gynecomastia as a side effect. [20] [21] Conversely, it does not appear to lower testosterone levels in men, and hence does not seem to have a risk of hypogonadism and associated side effects in men. [22]
CTA is a relatively weak estrogen, with about one-eighth the potency of DES. [2] [12] However, it is highly lipophilic and is stored in fat tissue for prolonged periods of time, with its slow release from fat resulting in a very long duration of action. [2] [12] [24] CTA itself is inactive; it behaves as a prodrug to desmethylchlorotrianisene (DMCTA), [3] [4] a weak estrogen that is formed as a metabolite via mono-O-demethylation of CTA in the liver. [2] [13] As such, the potency of CTA is reduced if it is given parenterally instead of orally. [2]
Although it is referred to as a weak estrogen and was used solely as an estrogen in clinical practice, CTA is a high-efficacy partial agonist of the estrogen receptor. [12] As such, it is a selective estrogen receptor modulator (SERM), with predominantly estrogenic effects but also with antiestrogenic effects, and was arguably the first SERM to ever be introduced. [11] CTA can antagonize estradiol at the level of the hypothalamus, resulting in disinhibition of the hypothalamic–pituitary–gonadal axis and an increase in estrogen levels. [12] Clomifene and tamoxifen were both derived from CTA via structural modification, and are much lower-efficacy partial agonists than CTA and hence much more antiestrogenic in comparison. [12] [9] As an example, chlorotrianisene produces gynecomastia in men, [21] albeit reportedly to a lesser extent than other estrogens, [25] while clomifene and tamoxifen do not and can be used to treat gynecomastia. [26]
CTA at a dosage of 48 mg/day inhibits ovulation in almost all women. [27] Conversely, it has been reported that CTA has no measurable effect on circulating levels of testosterone in men. [22] This is in contrast to other estrogens, like diethylstilbestrol, which can suppress testosterone levels by as much as 96%—or to an equivalent extent as castration. [22] These findings suggest that CTA is not an effective antigonadotropin in men. [22]
Chlorotrianisene, also known as tri-p-anisylchloroethylene (TACE) or as tris(p-methoxyphenyl)chloroethylene, is a synthetic nonsteroidal compound of the triphenylethylene group. [5] [7] [1] It is structurally related to the nonsteroidal estrogen diethylstilbestrol and to the SERMs clomifene and tamoxifen. [1] [12] [9]
CTA was introduced for medical use in the United States in 1952, and was subsequently introduced for use throughout Europe. [14] [6] It was the first estrogenic compound of the triphenylethylene series to be introduced. [11] CTA was derived from estrobin (DBE), a derivative of the very weakly estrogenic compound triphenylethylene (TPE), which in turn was derived from structural modification of diethylstilbestrol (DES). [2] [12] [24] [28] The SERMs clomifene and tamoxifen, as well as the antiestrogen ethamoxytriphetol, were derived from CTA via structural modification. [12] [9] [29] [30]
Chlorotrianisene is the generic name of the drug and its INN , USAN , and BAN . [5] [6] [7] It is also known as tri-p-anisylchloroethylene (TACE). [5] [6] [7]
CTA has been marketed under the brand names Tace, Estregur, Anisene, Clorotrisin, Merbentyl, Merbentul, and Triagen among many others. [5] [6]
CTA is no longer marketed and hence is no longer available in any country. [1] [15] It was previously used in the United States and Europe. [14] [6]
Clomifene, also known as clomiphene, is a medication used to treat infertility in women who do not ovulate, including those with polycystic ovary syndrome. It is taken by mouth.
Selective estrogen receptor modulators (SERMs), also known as estrogen receptor agonists/antagonists (ERAAs), are a class of drugs that act on estrogen receptors (ERs). Compared to pure ER agonists–antagonists, SERMs are more tissue-specific, allowing them to selectively inhibit or stimulate estrogen-like action in various tissues.
Tamoxifen, sold under the brand name Nolvadex among others, is a selective estrogen receptor modulator used to prevent breast cancer in women and men. It is also being studied for other types of cancer. It has been used for Albright syndrome. Tamoxifen is typically taken daily by mouth for five years for breast cancer.
Raloxifene, sold under the brand name Evista among others, is a medication used to prevent and treat osteoporosis in postmenopausal women and those on glucocorticoids. For osteoporosis it is less preferred than bisphosphonates. It is also used to reduce the risk of breast cancer in those at high risk. It is taken by mouth.
Stilbestrol, or stilboestrol, also known as 4,4'-dihydroxystilbene or 4,4'-stilbenediol, is a stilbenoid nonsteroidal estrogen and the parent compound of a group of more potent nonsteroidal estrogen derivatives that includes, most notably, diethylstilbestrol (DES). The term "stilbestrol" is often used incorrectly to refer to DES, but they are not the same compound.
Toremifene, sold under the brand name Fareston among others, is a medication which is used in the treatment of advanced breast cancer in postmenopausal women. It is taken by mouth.
A nonsteroidal compound is a drug that is not a steroid nor a steroid derivative. Nonsteroidal anti-inflammatory drugs (NSAIDs) are distinguished from corticosteroids as a class of anti-inflammatory agents.
Zuclomifene (INN; or zuclomiphene (USAN)) is a nonsteroidal selective estrogen receptor modulator (SERM) of the triphenylethylene group that was never marketed. It is one of the two stereoisomers of clomifene, which itself is a mixture of 38% zuclomifene and 62% enclomifene. Zuclomifene is the (Z)-stereoisomer of clomifene, while enclomifene is the (E)-stereoisomer. Whereas zuclomifene is described as mildly estrogenic, enclomifene is described as antiestrogenic. In accordance, unlike enclomifene, zuclomifene is antigonadotropic due to activation of the estrogen receptor and reduces testosterone levels in men. It is also about five times more potent than enclomifene in inducing ovulation.
Afimoxifene, also known as 4-hydroxytamoxifen (4-OHT) and by its tentative brand name TamoGel, is a selective estrogen receptor modulator (SERM) of the triphenylethylene group and an active metabolite of tamoxifen. The drug is under development under the tentative brand name TamoGel as a topical gel for the treatment of hyperplasia of the breast. It has completed a phase II clinical trial for cyclical mastalgia, but further studies are required before afimoxifene can be approved for this indication and marketed.
Nafoxidine or nafoxidine hydrochloride is a nonsteroidal selective estrogen receptor modulator (SERM) or partial antiestrogen of the triphenylethylene group that was developed for the treatment of advanced breast cancer by Upjohn in the 1970s but was never marketed. It was developed at around the same time as tamoxifen and clomifene, which are also triphenylethylene derivatives. The drug was originally synthesized by the fertility control program at Upjohn as a postcoital contraceptive, but was subsequently repurposed for the treatment of breast cancer. Nafoxidine was assessed in clinical trials in the treatment of breast cancer and was found to be effective. However, it produced side effects including ichthyosis, partial hair loss, and phototoxicity of the skin in almost all patients, and this resulted in the discontinuation of its development.
A nonsteroidal estrogen is an estrogen with a nonsteroidal chemical structure. The most well-known example is the stilbestrol estrogen diethylstilbestrol (DES). Although nonsteroidal estrogens formerly had an important place in medicine, they have gradually fallen out of favor following the discovery of toxicities associated with high-dose DES starting in the early 1970s, and are now almost never used. On the other hand, virtually all selective estrogen receptor modulators (SERMs) are nonsteroidal, with triphenylethylenes like tamoxifen and clomifene having been derived from DES, and these drugs remain widely used in medicine for the treatment of breast cancer among other indications. In addition to pharmaceutical drugs, many xenoestrogens, including phytoestrogens, mycoestrogens, and synthetic endocrine disruptors like bisphenol A, are nonsteroidal substances with estrogenic activity.
Broparestrol, also known as α-bromo-α,β-diphenyl-β-p-ethylphenylethylene (BDPE), is a synthetic, nonsteroidal selective estrogen receptor modulator (SERM) of the triphenylethylene group that has been used in Europe as a dermatological agent and for the treatment of breast cancer. The drug is described as slightly estrogenic and potently antiestrogenic, and inhibits mammary gland development and suppresses prolactin levels in animals. It is structurally related to clomifene and diethylstilbestrol. Broparestrol is a mixture of E- and Z- isomers, both of which are active, and are similarly antiestrogenic but, unlike broparestrol, were never marketed.
Triphenylethylene (TPE) is a simple aromatic hydrocarbon that possesses weak estrogenic activity. Its estrogenic effects were discovered in 1937. TPE was derived from structural modification of the more potent estrogen diethylstilbestrol, which is a member of the stilbestrol group of nonsteroidal estrogens.
Estrobin, also known as α,α-di(p-ethoxyphenyl)-β-phenylbromoethylene and commonly abbreviated as DBE, is a synthetic, nonsteroidal estrogen of the triphenylethylene group that was never marketed. Chlorotrianisene, and subsequently clomifene and tamoxifen, were derived from it. Estrobin, similarly to other triphenylethylenes, is very lipophilic and hence very long-lasting in its duration of action. Similarly to chlorotrianisene, estrobin behaves a prodrug to a much more potent estrogen in the body.
Ethamoxytriphetol is a synthetic nonsteroidal antiestrogen that was studied clinically in the late 1950s and early 1960s but was never marketed. MER-25 was first reported in 1958, and was the first antiestrogen to be discovered. It has been described as "essentially devoid of estrogenic activity" and as having "very low estrogenic activity in all species tested". However, some estrogenic effects in the uterus have been observed, so it is not a pure antiestrogen but is, instead, technically a selective estrogen receptor modulator (SERM). For all intents and purposes, it is a nearly pure antiestrogen, however.
GTx-758 is a synthetic nonsteroidal estrogen which was under development by GTx, Inc. for the treatment of advanced prostate cancer. As of 2016, it had completed two phase II clinical trials.
Triphenylchloroethylene, or triphenylchlorethylene, also known as chlorotriphenylethylene or as phenylstilbene chloride, is a synthetic nonsteroidal estrogen of the triphenylethylene group that was marketed in the 1940s for the treatment of menopausal symptoms, vaginal atrophy, lactation suppression, and all other estrogen-indicated conditions.
Droloxifene, also known as 3-hydroxytamoxifen, is a nonsteroidal selective estrogen receptor modulator (SERM) of the triphenylethylene group that was developed originally in Germany and later in Japan for the treatment of breast cancer, osteoporosis in men and postmenopausal women, and cardiovascular disorders but was abandoned and never marketed. It reached phase II and phase III clinical trials for these indications before development was discontinued in 2000. The drug was found to be significantly less effective than tamoxifen in the treatment of breast cancer in two phase III clinical trials.
Nitromifene (INNTooltip International Nonproprietary Name; also as the citrate salt nitromifene citrate (USANTooltip United States Adopted Name), developmental code names CI-628, CN-5518, CN-55945) is a nonsteroidal selective estrogen receptor modulator (SERM) related to triphenylethylenes like tamoxifen that was never marketed. It is a mixture of (E)- and (Z)-isomers that possess similar antiestrogenic activity. The drug was described in 1966. Along with tamoxifen, nafoxidine, and clomifene, it was one of the earliest SERMs.
A sex-hormonal agent, also known as a sex-hormone receptor modulator, is a type of hormonal agent which specifically modulates the effects of sex hormones and of their biological targets, the sex hormone receptors. The sex hormones include androgens such as testosterone, estrogens such as estradiol, and progestogens such as progesterone. Sex-hormonal agents may be either steroidal or nonsteroidal in chemical structure and may serve to either enhance, inhibit, or have mixed effects on the function of the sex hormone systems.