Equilin in conjugated equine estrogen promotes monocyte-endothelial adhesion via NF-κB signaling[3].

Absorption, Distribution and Excretion
Well absorbed.

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Metabolism / Metabolites
Hepatic
Hepatic.

Toxicity Summary
Estrogens enter the cells of responsive tissues (e.g., female organs, breasts, hypothalamus, pituitary) where they interact with a protein receptor, subsequently increasing the rate of synthesis of DNA, RNA, and some proteins. Estrogens decrease the secretion of gonadotropin-releasing hormone by the hypothalamus, reducing the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary.

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Protein Binding
90% bound to plasma proteins

[1]. Some biological properties of equilin. Biochem J. 1935;29(2):371-377.

[2]. Equilin, a principal component of the estrogen replacement therapy premarin, increases the growth of cortical neurons via an NMDA receptor-dependent mechanism. Exp Neurol. 1997;147(2):211-220.

[3]. Equilin in conjugated equine estrogen increases monocyte-endothelial adhesion via NF-κB signaling. PLoS One. 2019;14(1):e0211462. Published 2019 Jan 30.

Equilin is a 17-oxo steroid and a 3-hydroxy steroid. It derives from a hydride of an estrane.
An estrogenic steroid produced by horses. It has a total of four double bonds in the A- and B-ring. High concentration of equilin is found in the urine of pregnant mares.
Equilin is a naturally occurring steroid with estrogenic activity obtained from the urine of pregnant mares.
An estrogenic steroid produced by horses. It has a total of four double bonds in the A- and B-ring. High concentration of euilin is found in the urine of pregnant mares. Equilin is one of the estrogens present in the mixture of estrogens isolated from horse urine and marketed as Premarin. Premarin became the most commonly used form of estrogen for hormone replacement therapy in the United States of America. Estrone is the major estrogen in Premarin (about 50%) and equilin is present as about 25% of the total. Estrone is a major estrogen that is normally found in women. Equilin is not normally present in women, so there has been interest in the effects of equilin on the human body. The estrogens in Premarin are present mainly as "conjugates", modified chemical forms in which the active estrogen is coupled to another chemical group such as sulfate. Estrone sulfate is usually the major form of estrogen in women. After being taken into a woman's body, the conjugated estrogens of Premarin are converted to the active unconjugated estrogens or excreted from the woman's body. Estrone can be converted to estradiol, which is thought to be the major active estrogen in women.
An estrogenic steroid produced by HORSES. It has a total of four double bonds in the A- and B-ring. High concentration of euilin is found in the URINE of pregnant mares.

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Drug Indication
For the treatment of moderate to severe vasomotor symptoms associated with the menopause, atrophic vaginitis, osteoporosis, hypoestrogenism due to hypogonadism, castration, primary ovarian failure, breast cancer (for palliation only), and Advanced androgen-dependent carcinoma of the prostate (for palliation only)

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Mechanism of Action
Estrogens enter the cells of responsive tissues (e.g., female organs, breasts, hypothalamus, pituitary) where they interact with a protein receptor, subsequently increasing the rate of synthesis of DNA, RNA, and some proteins. Estrogens decrease the secretion of gonadotropin-releasing hormone by the hypothalamus, reducing the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary.

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Pharmacodynamics
Equilin is a component of Premarin (conjugated estrogens), a mixture of the water soluble salts of sulfate esters from estrone, equilin, 17 alpha-dihydroequilin, and other related steroids, may be derived from pregnant equine urine or yam and soy plants. Estrogens are important in the development and maintenance of the female reproductive system and secondary sex characteristics. They promote growth and development of the vagina, uterus, and fallopian tubes, and enlargement of the breasts. Indirectly, they contribute to the shaping of the skeleton, maintenance of tone and elasticity of urogenital structures, changes in the epiphyses of the long bones that allow for the pubertal growth spurt and its termination, growth of axillary and pubic hair, and pigmentation of the nipples and genitals. Decline of estrogenic activity at the end of the menstrual cycle can bring on menstruation, although the cessation of progesterone secretion is the most important factor in the mature ovulatory cycle. However, in the preovulatory or nonovulatory cycle, estrogen is the primary determinant in the onset of menstruation. Estrogens also affect the release of pituitary gonadotropins. The pharmacologic effects of conjugated estrogens are similar to those of endogenous estrogens.

C₁₈H₂₀O₂

268.35

268.146

474-86-2

Equilin-d4;285979-79-5

223368

White to off-white solid

1.2±0.1 g/cm3

459.1±45.0 °C at 760 mmHg

238-240ºC(lit.)

195.4±21.3 °C

0.0±1.2 mmHg at 25°C

1.626

3.53

1

2

0

20

466

3

OC1C=C2CC=C3[C@@]4([H])[C@@](C(CC4)=O)(CC[C@]3([H])C2=CC=1)C

WKRLQDKEXYKHJB-HFTRVMKXSA-N

InChI=1S/C18H20O2/c1-18-9-8-14-13-5-3-12(19)10-11(13)2-4-15(14)16(18)6-7-17(18)20/h3-5,10,14,16,19H,2,6-9H2,1H3/t14-,16+,18+/m1/s1

(9S,13S,14S)-3-hydroxy-13-methyl-9,11,12,14,15,16-hexahydro-6H-cyclopenta[a]phenanthren-17-one

7-Dehydroestrone; Equilin

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

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

DMSO: ~100 mg/mL (~372.7 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (9.32 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 (9.32 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 (9.32 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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 (Please use freshly prepared in vivo formulations for optimal results.)