Estrogen ester

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An estrogen ester is an ester of an estrogen, most typically of estradiol but also of other estrogens such as estrone, estriol, and even nonsteroidal estrogens like diethylstilbestrol. [1] [2] [3] Esterification renders estradiol into a prodrug of estradiol with increased resistance to first-pass metabolism, slightly improving its oral bioavailability. [1] [2] [4] In addition, estrogen esters have increased lipophilicity, which results in a longer duration when given by intramuscular or subcutaneous injection due to the formation of a long-lasting local depot in muscle and fat. [1] [2] [3] Conversely, this is not the case with intravenous injection or oral administration. [1] [5] Estrogen esters are rapidly hydrolyzed into their parent estrogen by esterases once they have been released from the depot. [1] [2] Because estradiol esters are prodrugs of estradiol, they are considered to be natural and bioidentical forms of estrogen. [2] [1] [6]

Contents

Estrogen esters are used in hormone therapy, hormonal contraception, and high-dose estrogen therapy (e.g., for prostate cancer and breast cancer), among other indications. [1] [2] The first estrogen ester to be marketed was estradiol benzoate in 1933, which was followed by many more. [7] [8] One of the most widely used estradiol esters is estradiol valerate, which was first introduced in 1954. [9] Other major estradiol esters that are or have been used in medicine include estradiol acetate, estradiol cypionate, estradiol dipropionate, estradiol enantate, estradiol undecylate, and polyestradiol phosphate (an estrogen ester polymer), as well as the nitrogen mustard alkylating antineoplastic agent estramustine phosphate (estradiol normustine phosphate). [2] [10]

The most common vehicles for injections of steroids and steroid esters are oil solutions, but aqueous solutions, aqueous suspensions, and emulsions have also been used. [11] [ additional citation(s) needed ] The durations of estrogen esters are not prolonged if they are given orally, vaginally, or by intravenous injection. [11]

Pharmacology

Estrogen esters are essentially inactive themselves, with esters such as estradiol valerate and estradiol sulfate having about 2% of the affinity of estradiol for the estrogen receptor. [12] Likewise, the estrogen ether mestranol (ethinylestradiol 3-methyl ether) has about 1% of the affinity of estradiol for the estrogen receptor. [12] Estrone sulfate has less than 1% of the affinity of estradiol for the estrogen receptor. [13] As such, estrogen esters do not bind to the estrogen receptor except at extremely high concentrations. [14] The residual affinity of estrogen esters for the estrogen receptor in bioassays may actually be due to conversion into the parent estrogen, as attempts to prevent or limit this conversion have been found to abolish binding to the estrogen receptor and estrogenicity. [15] [16] [17]

Affinities of estrogen receptor ligands for the ERα and ERβ
Ligand Other names Relative binding affinities (RBA, %)a Absolute binding affinities (Ki, nM)aAction
ERα ERβ ERα ERβ
Estradiol E2; 17β-Estradiol1001000.115 (0.04–0.24)0.15 (0.10–2.08)Estrogen
Estrone E1; 17-Ketoestradiol16.39 (0.7–60)6.5 (1.36–52)0.445 (0.3–1.01)1.75 (0.35–9.24)Estrogen
Estriol E3; 16α-OH-17β-E212.65 (4.03–56)26 (14.0–44.6)0.45 (0.35–1.4)0.7 (0.63–0.7)Estrogen
Estetrol E4; 15α,16α-Di-OH-17β-E24.03.04.919Estrogen
Alfatradiol 17α-Estradiol20.5 (7–80.1)8.195 (2–42)0.2–0.520.43–1.2Metabolite
16-Epiestriol 16β-Hydroxy-17β-estradiol7.795 (4.94–63)50 ? ?Metabolite
17-Epiestriol 16α-Hydroxy-17α-estradiol55.45 (29–103)79–80 ? ?Metabolite
16,17-Epiestriol 16β-Hydroxy-17α-estradiol1.013 ? ?Metabolite
2-Hydroxyestradiol 2-OH-E222 (7–81)11–352.51.3Metabolite
2-Methoxyestradiol 2-MeO-E20.0027–2.01.0 ? ?Metabolite
4-Hydroxyestradiol 4-OH-E213 (8–70)7–561.01.9Metabolite
4-Methoxyestradiol 4-MeO-E22.01.0 ? ?Metabolite
2-Hydroxyestrone 2-OH-E12.0–4.00.2–0.4 ? ?Metabolite
2-Methoxyestrone 2-MeO-E1<0.001–<1<1 ? ?Metabolite
4-Hydroxyestrone 4-OH-E11.0–2.01.0 ? ?Metabolite
4-Methoxyestrone 4-MeO-E1<1<1 ? ?Metabolite
16α-Hydroxyestrone 16α-OH-E1; 17-Ketoestriol2.0–6.535 ? ?Metabolite
2-Hydroxyestriol 2-OH-E32.01.0 ? ?Metabolite
4-Methoxyestriol 4-MeO-E31.01.0 ? ?Metabolite
Estradiol sulfate E2S; Estradiol 3-sulfate<1<1 ? ?Metabolite
Estradiol disulfate Estradiol 3,17β-disulfate0.0004 ? ? ?Metabolite
Estradiol 3-glucuronide E2-3G0.0079 ? ? ?Metabolite
Estradiol 17β-glucuronide E2-17G0.0015 ? ? ?Metabolite
Estradiol 3-gluc. 17β-sulfate E2-3G-17S0.0001 ? ? ?Metabolite
Estrone sulfate E1S; Estrone 3-sulfate<1<1>10>10Metabolite
Estradiol benzoate EB; Estradiol 3-benzoate10 ? ? ?Estrogen
Estradiol 17β-benzoate E2-17B11.332.6 ? ?Estrogen
Estrone methyl ether Estrone 3-methyl ether0.145 ? ? ?Estrogen
ent-Estradiol 1-Estradiol1.31–12.349.44–80.07 ? ?Estrogen
Equilin 7-Dehydroestrone13 (4.0–28.9)13.0–490.790.36Estrogen
Equilenin 6,8-Didehydroestrone2.0–157.0–200.640.62Estrogen
17β-Dihydroequilin 7-Dehydro-17β-estradiol7.9–1137.9–1080.090.17Estrogen
17α-Dihydroequilin 7-Dehydro-17α-estradiol18.6 (18–41)14–320.240.57Estrogen
17β-Dihydroequilenin 6,8-Didehydro-17β-estradiol35–6890–1000.150.20Estrogen
17α-Dihydroequilenin 6,8-Didehydro-17α-estradiol20490.500.37Estrogen
Δ8-Estradiol 8,9-Dehydro-17β-estradiol68720.150.25Estrogen
Δ8-Estrone 8,9-Dehydroestrone19320.520.57Estrogen
Ethinylestradiol EE; 17α-Ethynyl-17β-E2120.9 (68.8–480)44.4 (2.0–144)0.02–0.050.29–0.81Estrogen
Mestranol EE 3-methyl ether ?2.5 ? ?Estrogen
Moxestrol RU-2858; 11β-Methoxy-EE35–435–200.52.6Estrogen
Methylestradiol 17α-Methyl-17β-estradiol7044 ? ?Estrogen
Diethylstilbestrol DES; Stilbestrol129.5 (89.1–468)219.63 (61.2–295)0.040.05Estrogen
Hexestrol Dihydrodiethylstilbestrol153.6 (31–302)60–2340.060.06Estrogen
Dienestrol Dehydrostilbestrol37 (20.4–223)56–4040.050.03Estrogen
Benzestrol (B2) 114 ? ? ?Estrogen
Chlorotrianisene TACE1.74 ?15.30 ?Estrogen
Triphenylethylene TPE0.074 ? ? ?Estrogen
Triphenylbromoethylene TPBE2.69 ? ? ?Estrogen
Tamoxifen ICI-46,4743 (0.1–47)3.33 (0.28–6)3.4–9.692.5SERM
Afimoxifene 4-Hydroxytamoxifen; 4-OHT100.1 (1.7–257)10 (0.98–339)2.3 (0.1–3.61)0.04–4.8SERM
Toremifene 4-Chlorotamoxifen; 4-CT ? ?7.14–20.315.4SERM
Clomifene MRL-4125 (19.2–37.2)120.91.2SERM
Cyclofenil F-6066; Sexovid151–152243 ? ?SERM
Nafoxidine U-11,000A30.9–44160.30.8SERM
Raloxifene 41.2 (7.8–69)5.34 (0.54–16)0.188–0.5220.2SERM
Arzoxifene LY-353,381 ? ?0.179 ?SERM
Lasofoxifene CP-336,15610.2–16619.00.229 ?SERM
Ormeloxifene Centchroman ? ?0.313 ?SERM
Levormeloxifene 6720-CDRI; NNC-460,0201.551.88 ? ?SERM
Ospemifene Deaminohydroxytoremifene0.82–2.630.59–1.22 ? ?SERM
Bazedoxifene  ? ?0.053 ?SERM
Etacstil GW-56384.3011.5 ? ?SERM
ICI-164,384 63.5 (3.70–97.7)1660.20.08Antiestrogen
Fulvestrant ICI-182,78043.5 (9.4–325)21.65 (2.05–40.5)0.421.3Antiestrogen
Propylpyrazoletriol PPT49 (10.0–89.1)0.120.4092.8ERα agonist
16α-LE2 16α-Lactone-17β-estradiol14.6–570.0890.27131ERα agonist
16α-Iodo-E2 16α-Iodo-17β-estradiol30.22.30 ? ?ERα agonist
Methylpiperidinopyrazole MPP110.05 ? ?ERα antagonist
Diarylpropionitrile DPN0.12–0.256.6–1832.41.7ERβ agonist
8β-VE2 8β-Vinyl-17β-estradiol0.3522.0–8312.90.50ERβ agonist
Prinaberel ERB-041; WAY-202,0410.2767–72 ? ?ERβ agonist
ERB-196 WAY-202,196 ?180 ? ?ERβ agonist
Erteberel SERBA-1; LY-500,307 ? ?2.680.19ERβ agonist
SERBA-2  ? ?14.51.54ERβ agonist
Coumestrol 9.225 (0.0117–94)64.125 (0.41–185)0.14–80.00.07–27.0Xenoestrogen
Genistein 0.445 (0.0012–16)33.42 (0.86–87)2.6–1260.3–12.8Xenoestrogen
Equol 0.2–0.2870.85 (0.10–2.85) ? ?Xenoestrogen
Daidzein 0.07 (0.0018–9.3)0.7865 (0.04–17.1)2.085.3Xenoestrogen
Biochanin A 0.04 (0.022–0.15)0.6225 (0.010–1.2)1748.9Xenoestrogen
Kaempferol 0.07 (0.029–0.10)2.2 (0.002–3.00) ? ?Xenoestrogen
Naringenin 0.0054 (<0.001–0.01)0.15 (0.11–0.33) ? ?Xenoestrogen
8-Prenylnaringenin 8-PN4.4 ? ? ?Xenoestrogen
Quercetin <0.001–0.010.002–0.040 ? ?Xenoestrogen
Ipriflavone <0.01<0.01 ? ?Xenoestrogen
Miroestrol 0.39 ? ? ?Xenoestrogen
Deoxymiroestrol 2.0 ? ? ?Xenoestrogen
β-Sitosterol <0.001–0.0875<0.001–0.016 ? ?Xenoestrogen
Resveratrol <0.001–0.0032 ? ? ?Xenoestrogen
α-Zearalenol 48 (13–52.5) ? ? ?Xenoestrogen
β-Zearalenol 0.6 (0.032–13) ? ? ?Xenoestrogen
Zeranol α-Zearalanol48–111 ? ? ?Xenoestrogen
Taleranol β-Zearalanol16 (13–17.8)140.80.9Xenoestrogen
Zearalenone ZEN7.68 (2.04–28)9.45 (2.43–31.5) ? ?Xenoestrogen
Zearalanone ZAN0.51 ? ? ?Xenoestrogen
Bisphenol A BPA0.0315 (0.008–1.0)0.135 (0.002–4.23)19535Xenoestrogen
Endosulfan EDS<0.001–<0.01<0.01 ? ?Xenoestrogen
Kepone Chlordecone0.0069–0.2 ? ? ?Xenoestrogen
o,p'-DDT 0.0073–0.4 ? ? ?Xenoestrogen
p,p'-DDT 0.03 ? ? ?Xenoestrogen
Methoxychlor p,p'-Dimethoxy-DDT0.01 (<0.001–0.02)0.01–0.13 ? ?Xenoestrogen
HPTE Hydroxychlor; p,p'-OH-DDT1.2–1.7 ? ? ?Xenoestrogen
Testosterone T; 4-Androstenolone<0.0001–<0.01<0.002–0.040>5000>5000Androgen
Dihydrotestosterone DHT; 5α-Androstanolone0.01 (<0.001–0.05)0.0059–0.17221–>500073–1688Androgen
Nandrolone 19-Nortestosterone; 19-NT0.010.2376553Androgen
Dehydroepiandrosterone DHEA; Prasterone0.038 (<0.001–0.04)0.019–0.07245–1053163–515Androgen
5-Androstenediol A5; Androstenediol6173.60.9Androgen
4-Androstenediol 0.50.62319Androgen
4-Androstenedione A4; Androstenedione<0.01<0.01>10000>10000Androgen
3α-Androstanediol 3α-Adiol0.070.326048Androgen
3β-Androstanediol 3β-Adiol3762Androgen
Androstanedione 5α-Androstanedione<0.01<0.01>10000>10000Androgen
Etiocholanedione 5β-Androstanedione<0.01<0.01>10000>10000Androgen
Methyltestosterone 17α-Methyltestosterone<0.0001 ? ? ?Androgen
Ethinyl-3α-androstanediol 17α-Ethynyl-3α-adiol4.0<0.07 ? ?Estrogen
Ethinyl-3β-androstanediol 17α-Ethynyl-3β-adiol505.6 ? ?Estrogen
Progesterone P4; 4-Pregnenedione<0.001–0.6<0.001–0.010 ? ?Progestogen
Norethisterone NET; 17α-Ethynyl-19-NT0.085 (0.0015–<0.1)0.1 (0.01–0.3)1521084Progestogen
Norethynodrel 5(10)-Norethisterone0.5 (0.3–0.7)<0.1–0.221453Progestogen
Tibolone 7α-Methylnorethynodrel0.5 (0.45–2.0)0.2–0.076 ? ?Progestogen
Δ4-Tibolone 7α-Methylnorethisterone0.069–<0.10.027–<0.1 ? ?Progestogen
3α-Hydroxytibolone 2.5 (1.06–5.0)0.6–0.8 ? ?Progestogen
3β-Hydroxytibolone 1.6 (0.75–1.9)0.070–0.1 ? ?Progestogen
Footnotes:a = (1) Binding affinity values are of the format "median (range)" (# (#–#)), "range" (#–#), or "value" (#) depending on the values available. The full sets of values within the ranges can be found in the Wiki code. (2) Binding affinities were determined via displacement studies in a variety of in-vitro systems with labeled estradiol and human ERα and ERβ proteins (except the ERβ values from Kuiper et al. (1997), which are rat ERβ). Sources: See template page.
Affinities and estrogenic potencies of estrogen esters and ethers at the estrogen receptors
Estrogen Other names RBA Tooltip Relative binding affinity (%)a REP (%)b
ER ERα ERβ
Estradiol E2100100100
Estradiol 3-sulfate E2S; E2-3S ?0.020.04
Estradiol 3-glucuronide E2-3G ?0.020.09
Estradiol 17β-glucuronide E2-17G ?0.0020.0002
Estradiol benzoate EB; Estradiol 3-benzoate101.10.52
Estradiol 17β-acetate E2-17A31–4524 ?
Estradiol diacetate EDA; Estradiol 3,17β-diacetate ?0.79 ?
Estradiol propionate EP; Estradiol 17β-propionate19–262.6 ?
Estradiol valerate EV; Estradiol 17β-valerate2–110.04–21 ?
Estradiol cypionate EC; Estradiol 17β-cypionate ?c4.0 ?
Estradiol palmitate Estradiol 17β-palmitate0 ? ?
Estradiol stearate Estradiol 17β-stearate0 ? ?
Estrone E1; 17-Ketoestradiol115.3–3814
Estrone sulfate E1S; Estrone 3-sulfate20.0040.002
Estrone glucuronide E1G; Estrone 3-glucuronide ?<0.0010.0006
Ethinylestradiol EE; 17α-Ethynylestradiol10017–150129
Mestranol EE 3-methyl ether11.3–8.20.16
Quinestrol EE 3-cyclopentyl ether ?0.37 ?
Footnotes:a = Relative binding affinities (RBAs) were determined via in-vitro displacement of labeled estradiol from estrogen receptors (ERs) generally of rodent uterine cytosol. Estrogen esters are variably hydrolyzed into estrogens in these systems (shorter ester chain length -> greater rate of hydrolysis) and the ER RBAs of the esters decrease strongly when hydrolysis is prevented. b = Relative estrogenic potencies (REPs) were calculated from half-maximal effective concentrations (EC50) that were determined via in-vitro β‐galactosidase (β-gal) and green fluorescent protein (GFP) production assays in yeast expressing human ERα and human ERβ. Both mammalian cells and yeast have the capacity to hydrolyze estrogen esters. c = The affinities of estradiol cypionate for the ERs are similar to those of estradiol valerate and estradiol benzoate (figure). Sources: See template page.

In general, the longer the fatty acid ester chain of an estrogen ester, the greater its lipophilicity, and the longer the duration of the estrogen ester with intramuscular injection. [1] [10] It has been said that, via intramuscular injection, the duration of estradiol benzoate (with an ester of length 1 carbon plus a benzene ring) is 2 to 3 days, of estradiol dipropionate (with two esters each of length 2 carbons) is 1 to 2 weeks, of estradiol valerate (ester of 5 carbons) is 1 to 3 weeks, and of estradiol cypionate (ester of 3 carbons plus a cyclopentane ring) is 3 to 4 weeks. [18] Estradiol enantate (ester of 7 carbons) has a duration of around 20 days. [2] [19] [20] Likewise, estradiol undecylate (ester of 10 carbons) has a very extended duration, which is longer than that of all of the aforementioned esters. [10] [21] [22]

Pharmacokinetics of three estradiol esters by intramuscular injection
EstrogenDose Cmax Tmax Duration
Estradiol benzoate 5 mgE2: 940 pg/mL
E1: 343 pg/mL
E2: 1.8 days
E1: 2.4 days
4–5 days
Estradiol valerate 5 mgE2: 667 pg/mL
E1: 324 pg/mL
E2: 2.2 days
E1: 2.7 days
7–8 days
Estradiol cypionate 5 mgE2: 338 pg/mL
E1: 145 pg/mL
E2: 3.9 days
E1: 5.1 days
11 days
Notes: All via i.m. injection of oil solution. Determinations via radioimmunoassay with chromatographic separation. Sources: See template.
Potencies and durations of natural estrogens by intramuscular injection
EstrogenFormDose (mg)Duration by dose (mg)
EPDCICD
Estradiol Aq. soln. ?<1 d
Oil soln.40–601–2 ≈ 1–2 d
Aq. susp. ?3.50.5–2 ≈ 2–7 d; 3.5 ≈ >5 d
Microsph. ?1 ≈ 30 d
Estradiol benzoate Oil soln.25–351.66 ≈ 2–3 d; 5 ≈ 3–6 d
Aq. susp.2010 ≈ 16–21 d
Emulsion ?10 ≈ 14–21 d
Estradiol dipropionate Oil soln.25–305 ≈ 5–8 d
Estradiol valerate Oil soln.20–3055 ≈ 7–8 d; 10 ≈ 10–14 d;
40 ≈ 14–21 d; 100 ≈ 21–28 d
Estradiol benz. butyrate Oil soln. ?1010 ≈ 21 d
Estradiol cypionate Oil soln.20–305 ≈ 11–14 d
Aq. susp. ?55 ≈ 14–24 d
Estradiol enanthate Oil soln. ?5–1010 ≈ 20–30 d
Estradiol dienanthate Oil soln. ?7.5 ≈ >40 d
Estradiol undecylate Oil soln. ?10–20 ≈ 40–60 d;
25–50 ≈ 60–120 d
Polyestradiol phosphate Aq. soln.40–6040 ≈ 30 d; 80 ≈ 60 d;
160 ≈ 120 d
Estrone Oil soln. ?1–2 ≈ 2–3 d
Aq. susp. ?0.1–2 ≈ 2–7 d
Estriol Oil soln. ?1–2 ≈ 1–4 d
Polyestriol phosphate Aq. soln. ?50 ≈ 30 d; 80 ≈ 60 d
Notes and sources
Notes: All aqueous suspensions are of microcrystalline particle size. Estradiol production during the menstrual cycle is 30–640 µg/d (6.4–8.6 mg total per month or cycle). The vaginal epithelium maturation dosage of estradiol benzoate or estradiol valerate has been reported as 5 to 7 mg/week. An effective ovulation-inhibiting dose of estradiol undecylate is 20–30 mg/month. Sources: See template.

Polyestradiol phosphate is an atypical estradiol ester. [23] [24] It is a phosphoric acid ester of estradiol in the form of a polymer, with an average polymer chain length of approximately 13  repeat units of estradiol phosphate. [23] It is slowly cleaved into estradiol and phosphoric acid by phosphatases. [23] Compared to conventional estradiol esters, polyestradiol phosphate has an extremely long duration; its elimination half-life is approximately 70 days. [24] Whereas conventional estradiol esters form a long-lasting depot in muscle and fat at the site of injection, [1] this is not the case with polyestradiol phosphate. [25] Instead, polyestradiol phosphate is taken up rapidly into the bloodstream following injection (by 90% within 24 hours), where it circulates, and is accumulated in the reticuloendothelial system. [25] Unlike other estradiol esters, polyestradiol phosphate is resistant to hydrolysis, which may be because it is a phosphatase inhibitor and may inhibit its own metabolism. [23]

Estrogen esters also occur naturally in the body, for instance estrogen conjugates like estrone sulfate and estrone glucuronide and the very long-lived lipoidal estradiol, which is constituted by ultra-long-chain esters like estradiol palmitate (ester of 16 carbons) and estradiol stearate (ester of 18 carbons). [1] [2] [26]

Chemistry

Estradiol plus the fatty acid valeric acid (valerate) equals estradiol valerate, a C17b ester of estradiol and one of the most widely used estrogen esters. Estradiol esterification into estradiol valerate.png
Estradiol plus the fatty acid valeric acid (valerate) equals estradiol valerate, a C17β ester of estradiol and one of the most widely used estrogen esters.
Polyestradiol phosphate, a polymer of estradiol phosphate, the C17b phosphoric acid ester of estradiol. It has on average of 13 repeat units. Polyestradiol phosphate.svg
Polyestradiol phosphate, a polymer of estradiol phosphate, the C17β phosphoric acid ester of estradiol. It has on average of 13 repeat units.

Estradiol esters have an ester moiety, usually a straight-chain fatty acid (e.g., valeric acid) or an aromatic fatty acid (e.g., benzoic acid), attached at the C3 and/or C17β positions of the steroid nucleus. These alkoxy moieties are substituted in place of the hydroxyl groups present in the unesterified estradiol molecule. Fatty acid esters serve to increase the lipophilicity of estradiol, increasing its solubility in fat. This causes them to form a depot with intramuscular or subcutaneous injection and gives them a long duration when administered by these routes.

Some estradiol esters have other moieties instead of fatty acids as the esters. Such esters include sulfuric acid (as in estradiol sulfate), sulfamic acid (as in estradiol sulfamate), phosphoric acid (as in estradiol phosphate), glucuronic acid (as in estradiol glucuronide, and others (e.g., estramustine phosphate (estradiol 3-normustine 17β-phosphate)). These esters are all hydrophilic, and have greater water solubility than estradiol or fatty acid estradiol esters. Unlike fatty acid estradiol esters, water-soluble estradiol esters can be administered by intravenous injection.

A few estrogen esters are polymers. These include polyestradiol phosphate and polyestriol phosphate, which are polymers of estradiol phosphate and estriol phosphate monomers, respectively. The monomers are connected in both cases by phosphate groups via the C3 and C17β positions. Polyestradiol phosphate has an average polymer chain length of approximately 13  repeat units of estradiol phosphate. [23] That is, each polyestradiol phosphate molecule is a polymer consisting on average of 13 estradiol phosphate molecules bonded together. [23] These polymeric estrogen esters are hydrophilic and water-soluble. Upon intramuscular injection, they do not form a depot and instead are rapidly absorbed into the circulation. However, they are only slowly cleaved into monomers, and as a result, have a very long duration in the body even outlasting that of many longer-chain fatty-acid estrogen esters.

Chemical structures of estradiol and major estradiol esters
Structural properties of selected estradiol esters
EstrogenStructureEster(s)Relative
mol. weight
Relative
E2 contentb
log Pc
Position(s)Moiet(ies)TypeLengtha
Estradiol
Estradiol.svg
1.001.004.0
Estradiol acetate
Estradiol 3-acetate.svg
C3 Ethanoic acid Straight-chain fatty acid21.150.874.2
Estradiol benzoate
Estradiol benzoate.svg
C3 Benzoic acid Aromatic fatty acid– (~4–5)1.380.724.7
Estradiol dipropionate
Estradiol dipropionate.svg
C3, C17β Propanoic acid (×2)Straight-chain fatty acid3 (×2)1.410.714.9
Estradiol valerate
Estradiol valerate.svg
C17β Pentanoic acid Straight-chain fatty acid51.310.765.6–6.3
Estradiol benzoate butyrate
Estradiol butyrate benzoate.svg
C3, C17β Benzoic acid, butyric acid Mixed fatty acid– (~6, 2)1.640.616.3
Estradiol cypionate
Estradiol 17 beta-cypionate.svg
C17β Cyclopentylpropanoic acid Cyclic fatty acid– (~6)1.460.696.9
Estradiol enanthate
Estradiol enanthate.png
C17β Heptanoic acid Straight-chain fatty acid71.410.716.7–7.3
Estradiol dienanthate
Estradiol dienanthate.svg
C3, C17β Heptanoic acid (×2)Straight-chain fatty acid7 (×2)1.820.558.1–10.4
Estradiol undecylate
Estradiol undecylate.svg
C17β Undecanoic acid Straight-chain fatty acid111.620.629.2–9.8
Estradiol stearate
Estradiol stearate structure.svg
C17β Octadecanoic acid Straight-chain fatty acid181.980.5112.2–12.4
Estradiol distearate
Estradiol distearate.svg
C3, C17β Octadecanoic acid (×2)Straight-chain fatty acid18 (×2)2.960.3420.2
Estradiol sulfate
Estradiol sulfate.svg
C3 Sulfuric acid Water-soluble conjugate1.290.770.3–3.8
Estradiol glucuronide
Estradiol sulfate.svg
C17β Glucuronic acid Water-soluble conjugate1.650.612.1–2.7
Estramustine phosphate d
Estramustine phosphate.svg
C3, C17β Normustine, phosphoric acid Water-soluble conjugate1.910.522.9–5.0
Polyestradiol phosphate e
Polyestradiol phosphate.svg
C3–C17β Phosphoric acid Water-soluble conjugate1.23f0.81f2.9g
Footnotes:a = Length of ester in carbon atoms for straight-chain fatty acids or approximate length of ester in carbon atoms for aromatic or cyclic fatty acids. b = Relative estradiol content by weight (i.e., relative estrogenic exposure). c = Experimental or predicted octanol/water partition coefficient (i.e., lipophilicity/hydrophobicity). Retrieved from PubChem, ChemSpider, and DrugBank. d = Also known as estradiol normustine phosphate. e = Polymer of estradiol phosphate (~13 repeat units). f = Relative molecular weight or estradiol content per repeat unit. g = log P of repeat unit (i.e., estradiol phosphate). Sources: See individual articles.

See also

Related Research Articles

<span class="mw-page-title-main">Estradiol valerate</span> Chemical compound

Estradiol valerate (EV), sold for use by mouth under the brand name Progynova and for use by injection under the brand names Delestrogen and Progynon Depot among others, is an estrogen medication. It is used in hormone therapy for menopausal symptoms and low estrogen levels, hormone therapy for transgender people, and in hormonal birth control. It is also used in the treatment of prostate cancer. The medication is taken by mouth or by injection into muscle or fat once every 1 to 4 weeks.

<span class="mw-page-title-main">Polyestradiol phosphate</span> Chemical compound

Polyestradiol phosphate (PEP), sold under the brand name Estradurin, is an estrogen medication which is used primarily in the treatment of prostate cancer in men. It is also used in women to treat breast cancer, as a component of hormone therapy to treat low estrogen levels and menopausal symptoms, and as a component of feminizing hormone therapy for transgender women. It is given by injection into muscle once every four weeks.

Combined injectable contraceptives (CICs) are a form of hormonal birth control for women. They consist of monthly injections of combined formulations containing an estrogen and a progestin to prevent pregnancy.

<span class="mw-page-title-main">Estradiol benzoate</span> Chemical compound

Estradiol benzoate (EB), sold under the brand name Progynon-B among others, is an estrogen medication which is used in hormone therapy for menopausal symptoms and low estrogen levels in women, in hormone therapy for transgender women, and in the treatment of gynecological disorders. It is also used in the treatment of prostate cancer in men. Estradiol benzoate is used in veterinary medicine as well. When used clinically, the medication is given by injection into muscle usually two to three times per week.

<span class="mw-page-title-main">Estradiol cypionate</span> Chemical compound

Estradiol cypionate (EC), sold under the brand name Depo-Estradiol among others, is an estrogen medication which is used in hormone therapy for menopausal symptoms and low estrogen levels in women, in hormone therapy for trans women, and in hormonal birth control for women. It is given by injection into muscle once every 1 to 4 weeks.

<span class="mw-page-title-main">Estradiol enantate</span> Chemical compound

Estradiol enantate, also spelled estradiol enanthate and sold under the brand names Perlutal and Topasel among others, is an estrogen medication which is used in hormonal birth control for women. It is formulated in combination with dihydroxyprogesterone acetophenide, a progestin, and is used specifically as a combined injectable contraceptive. Estradiol enantate is not available for medical use alone. The medication, in combination with DHPA, is given by injection into muscle once a month.

<span class="mw-page-title-main">Estradiol undecylate</span> Chemical compound

Estradiol undecylate, also known as estradiol undecanoate and formerly sold under the brand names Delestrec and Progynon Depot 100 among others, is an estrogen medication which has been used in the treatment of prostate cancer in men. It has also been used as a part of hormone therapy for transgender women. Although estradiol undecylate has been used in the past, it was discontinued and hence is no longer available. The medication has been given by injection into muscle usually once a month.

<span class="mw-page-title-main">Estradiol dipropionate</span> Chemical compound

Estradiol dipropionate (EDP), sold under the brand names Agofollin, Di-Ovocylin, and Progynon DP among others, is an estrogen medication which has been used in hormone therapy for menopausal symptoms and low estrogen levels in women and in the treatment of gynecological disorders. It has also been used in feminizing hormone therapy for transgender women and in the treatment of prostate cancer in men. Although widely used in the past, estradiol dipropionate has largely been discontinued and is mostly no longer available today. It appears to remain in use only in Japan, Macedonia, and Australia. Estradiol dipropionate is given by injection into muscle at intervals ranging from once or twice a week to once every week and a half to two weeks.

Estradiol stearate (E2-17-St), also known as estradiol octadecanoate and sold under the brand name Depofollan, is a naturally occurring estrogen and an estrogen ester – specifically, the C17β stearate ester of estradiol. It occurs in the body as a very long-lasting metabolite and prohormone of estradiol. The compound is one of the components that collectively constitute lipoidal estradiol, another of which is estradiol palmitate. It is extremely lipophilic and hydrophobic. Estradiol stearate has no affinity for the estrogen receptor, requiring transformation into estradiol via esterases for its estrogenic activity. The compound does not bind to sex hormone-binding globulin or α-fetoprotein, instead being transported by lipoproteins such as high-density lipoprotein and low-density lipoprotein.

<span class="mw-page-title-main">Steroid ester</span> Class of chemical compounds

A steroid ester is an ester of a steroid. They include androgen esters, estrogen esters, progestogen esters, and corticosteroid esters. Steroid esters may be naturally occurring/endogenous like DHEA sulfate or synthetic like estradiol valerate. Esterification is useful because it is often able to render the parent steroid into a prodrug of itself with altered chemical properties such as improved metabolic stability, water solubility, and/or lipophilicity. This, in turn, can enhance pharmacokinetics, for instance by improving the steroid's bioavailability and/or conferring depot activity and hence an extended duration with intramuscular or subcutaneous injection.

<span class="mw-page-title-main">Estradiol benzoate butyrate</span> Chemical compound

Estradiol benzoate butyrate (EBB), sold under the brand names Neolutin N, Redimen, Soluna, and Unijab and formerly known under the developmental code name Unimens, is an estrogen medication which is used in hormonal birth control for women. It is formulated in combination with dihydroxyprogesterone acetophenide, a progestin, and is used specifically as a combined injectable contraceptive. EBB is not available for medical use alone. The medication, in combination with DHPA, is given by injection into muscle once a month.

Lipoidal estradiol (LE2) is the variety of endogenous C17β long-chain fatty acid esters of estradiol which are formed as metabolites of estradiol. Important examples of these esters include estradiol arachidonate, estradiol lineolate, estradiol oleate, estradiol palmitate, and estradiol stearate. LE2 are estrogens but do not bind to the estrogen receptor, instead acting as prohormones of estradiol. Relative to estradiol, they have far longer-lasting durations of effect due to their much slower rates of metabolism and clearance. It has been hypothesized that LE2 may serve as a store of estrogen for when estradiol levels become low. LE2 are highly lipophilic and hydrophobic and are found in highest concentrations in adipose tissue and other estrogen-sensitive tissues and in low but detectable concentrations in circulation, with none excreted in urine. They have been referred to as the "endogenous counterparts of the synthetic esters of estrogens" like estradiol valerate and estradiol cypionate.

<span class="mw-page-title-main">Estradiol (medication)</span> Steroidal hormone medication

Estradiol (E2) is a medication and naturally occurring steroid hormone. It is an estrogen and is used mainly in menopausal hormone therapy and to treat low sex hormone levels in women. It is also used in hormonal birth control for women, in feminizing hormone therapy for transgender women, and in the treatment of hormone-sensitive cancers like prostate cancer in men and breast cancer in women, among other uses. Estradiol can be taken by mouth, held and dissolved under the tongue, as a gel or patch that is applied to the skin, in through the vagina, by injection into muscle or fat, or through the use of an implant that is placed into fat, among other routes.

<span class="mw-page-title-main">Estradiol glucuronide</span> Chemical compound

Estradiol glucuronide, or estradiol 17β-D-glucuronide, is a conjugated metabolite of estradiol. It is formed from estradiol in the liver by UDP-glucuronyltransferase via attachment of glucuronic acid and is eventually excreted in the urine by the kidneys. It has much higher water solubility than does estradiol. Glucuronides are the most abundant estrogen conjugates.

<span class="mw-page-title-main">Estrone glucuronide</span> Chemical compound

Estrone glucuronide, or estrone-3-D-glucuronide, is a conjugated metabolite of estrone. It is formed from estrone in the liver by UDP-glucuronyltransferase via attachment of glucuronic acid and is eventually excreted in the urine by the kidneys. It has much higher water solubility than does estrone. Glucuronides are the most abundant estrogen conjugates and estrone glucuronide is the dominant metabolite of estradiol.

<span class="mw-page-title-main">Estriol (medication)</span> Chemical compound

Estriol (E3), sold under the brand name Ovestin among others, is an estrogen medication and naturally occurring steroid hormone which is used in menopausal hormone therapy. It is also used in veterinary medicine as Incurin to treat urinary incontinence due to estrogen deficiency in dogs. The medication is taken by mouth in the form of tablets, as a cream that is applied to the skin, as a cream or pessary that is applied in the vagina, and by injection into muscle.

<span class="mw-page-title-main">Estrone sulfate (medication)</span> Chemical compound

Estrone sulfate (E1S) is an estrogen medication and naturally occurring steroid hormone. It is used in menopausal hormone therapy among other indications. As the sodium salt, it is the major estrogen component of conjugated estrogens (Premarin) and esterified estrogens. In addition, E1S is used on its own as the piperazine salt estropipate. The compound also occurs as a major and important metabolite of estradiol and estrone. E1S is most commonly taken by mouth, but in the form of Premarin can also be taken by parenteral routes such as transdermal, vaginal, and injection.

The pharmacology of estradiol, an estrogen medication and naturally occurring steroid hormone, concerns its pharmacodynamics, pharmacokinetics, and various routes of administration.

<span class="mw-page-title-main">Pharmacokinetics of estradiol</span>

The pharmacology of estradiol, an estrogen medication and naturally occurring steroid hormone, concerns its pharmacodynamics, pharmacokinetics, and various routes of administration.

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Further reading