Moxestrol, sold under the brand name Surestryl, is an

estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal acti ...

medication which has been used in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

for the treatment of

menopausal symptoms Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often d ...

and

menstrual disorder A menstrual disorder is characterized as any abnormal condition with regards to a person's menstrual cycle. There are many different types of menstrual disorders that vary with signs and symptoms, including pain during menstruation, heavy bleeding ...

s. It is taken

by mouth Oral administration is a route of administration where a substance is taken through the mouth. Per os abbreviated to P.O. is sometimes used as a direction for medication to be taken orally. Many medications are taken orally because they are i ...

. In addition to its use as a medication, moxestrol has been used in

scientific research The scientific method is an empirical method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific m ...

as a

radioligand A radioligand is a radioactive biochemical substance (in particular, a ligand that is radiolabeled) that is used for diagnosis or for research-oriented study of the receptor systems of the body. In a neuroimaging application the radioligand is inj ...

of the

estrogen receptor Estrogen receptors (ERs) are a group of proteins found inside cells. They are receptors that are activated by the hormone estrogen ( 17β-estradiol). Two classes of ER exist: nuclear estrogen receptors (ERα and ERβ), which are members of the ...

Medical uses

Moxestrol is or has been used in the treatment of

and

s. It has been used at dosages of 50 to 150 µg per week for long-term therapy to 25 to 250 µg per day for short-term therapy.

Pharmacology

Pharmacodynamics

Moxestrol is an

, or an

agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...

of the

s. It is the 11β-methoxy derivative of

ethinylestradiol Ethinylestradiol (EE) is an estrogen medication which is used widely in birth control pills in combination with progestins. In the past, EE was widely used for various indications such as the treatment of menopausal symptoms, gynecological disord ...

and is one of the most potent estrogens known, being some 10 to 100 times more potent than

estradiol Estradiol (E2), also spelled oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of the estrous and menstrual female reproductive cycles. Estradiol is responsible for the development of f ...

and about 5-fold more potent than ethinylestradiol. The very high potency of moxestrol has been attributed to its high

affinity Affinity may refer to: Commerce, finance and law * Affinity (law), kinship by marriage * Affinity analysis, a market research and business management technique * Affinity Credit Union, a Saskatchewan-based credit union * Affinity Equity Partn ...

for the

(ER), its negligible plasma binding to

sex hormone binding globulin Sex hormone-binding globulin (SHBG) or sex steroid-binding globulin (SSBG) is a glycoprotein that binds to androgens and estrogens. When produced by the Sertoli cells in the seminiferous tubules of the testis, it has also been called androgen-bi ...

and low binding to

serum albumin Serum albumin, often referred to simply as blood albumin, is an albumin (a type of globular protein) found in vertebrate blood. Human serum albumin is encoded by the ''ALB'' gene. Other mammalian forms, such as bovine serum albumin, are chemical ...

, and its lower relative rate of

metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

. In contrast to estradiol, which has roughly the same affinity for both ERs (K_i = 0.12 nM and 0.15 nM, respectively), moxestrol possesses several-fold

selectivity Selectivity may refer to: Psychology and behaviour * Choice, making a selection among options * Discrimination, the ability to recognize differences * Socioemotional selectivity theory, in social psychology Engineering * Selectivity (radio), a ...

for the

ERα Estrogen receptor alpha (ERα), also known as NR3A1 (nuclear receptor subfamily 3, group A, member 1), is one of two main types of estrogen receptor, a nuclear receptor (mainly found as a chromatin-binding protein) that is activated by the sex ...

(K_i = 0.50 nM) over

ERβ Estrogen receptor beta (ERβ) also known as NR3A2 (nuclear receptor subfamily 3, group A, member 2) is one of two main types of estrogen receptor—a nuclear receptor which is activated by the sex hormone estrogen. In humans ERβ is encoded by ...

(K_i = 2.6 nM).

Pharmacokinetics

The

bioavailability In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. H ...

of moxestrol is 33%. Its

plasma protein binding Plasma protein binding refers to the degree to which medications attach to proteins within the blood. A drug's efficiency may be affected by the degree to which it binds. The less bound a drug is, the more efficiently it can traverse or diffuse th ...

is minimal. The medication is

metabolized Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

in the

liver The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...

. Its

biological half-life Biological half-life (also known as elimination half-life, pharmacologic half-life) is the time taken for concentration of a biological substance (such as a medication) to decrease from its maximum concentration ( Cmax) to half of Cmax in the bl ...

is 8.2 hours.

Chemistry

Moxestrol, also known as 11β-methoxy-17α-ethynylestradiol (11β-MeO-EE) or as 11β-methoxy-17α-ethynylestra-1,3,5(10)-triene-3,17β-diol, is a

synthetic Synthetic things are composed of multiple parts, often with the implication that they are artificial. In particular, 'synthetic' may refer to: Science * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic o ...

estrane Estrane is a C18 steroid derivative, with a gonane core. ''Estrenes'' are estrane derivatives that contain a double bond, with an example being nandrolone. ''Estratrienes'' (estrins) are estrane derivatives that contain three double bonds, for i ...

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...

and a

derivative In mathematics, the derivative of a function of a real variable measures the sensitivity to change of the function value (output value) with respect to a change in its argument (input value). Derivatives are a fundamental tool of calculus. F ...

. It is specifically a derivative of

(17α-ethynylestradiol) with a

methoxy group In organic chemistry, a methoxy group is the functional group consisting of a methyl group bound to oxygen. This alkoxy group has the formula . On a benzene ring, the Hammett equation classifies a methoxy substituent at the ''para'' position as ...

at the C11β position and a derivative of 11β-methoxyestradiol with an

ethynyl group In organic chemistry, the term ethynyl designates a functional group with a double bond with 2 carbon atoms both with sp hybridisation and a triple bond(1 sigma and 2 pi bond) . It is a species similar to acetylene (or in IUPAC ethyne ) with a less ...

at the C17α position. The compound is the C11β

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

or C11

epimer In stereochemistry, an epimer is one of a pair of diastereomers. The two epimers have opposite configuration at only one stereogenic center out of at least two. All other stereogenic centers in the molecules are the same in each. Epimerization is ...

RU-16117 RU-16117 is an estrogen medication which was investigated for the potential treatment of symptoms of estrogen deficiency such as hot flashes and osteoporosis in women but was never marketed. It was developed for use by mouth. Pharmacology Phar ...

(11α-methoxy-17α-ethynylestradiol.

Society and culture

Generic names

''Moxestrol'' is the generic name of the drug and its . It is also known by its developmental code name ''R-2858'' or ''RU-2858''.

Brand names

Moxestrol is or has been marketed under the brand name ''Surestryl''.

Availability

Moxestrol is or has been marketed in

References

{{Estrogen receptor modulators Abandoned drugs Ethynyl compounds Diols Estranes Estrogen ethers Synthetic estrogens