Title: Estramustine
CAS Registry Number: 2998-57-4
CAS Name: (17b)-Estra-1,3,5(10)-triene-3,17-diol 3-[bis(2-chloroethyl)carbamate]
Additional Names: estradiol 3-bis(2-chloroethyl)carbamate; estra-1,3,5(10)triene-3,17b-diol 3-[N,N-bis(2-chloroethyl)carbamate]
Manufacturers' Codes: Ro-21-8837
Molecular Formula: C23H31Cl2NO3
Molecular Weight: 440.40
Percent Composition: C 62.73%, H 7.09%, Cl 16.10%, N 3.18%, O 10.90%
Literature References: Carbamate ester linking estradiol to nor-nitrogen mustard; depolymerizes microtubules by binding to microtubule associated proteins (MAPs). Prepn: BE 646319; Fex et al., US 3299104 (1963, 1967 to AB Leo); Niculescu-Duvaz et al., J. Med. Chem. 10, 172 (1967). Clinical results: Anderes, Praxis 60, 1375 (1971); Muntzing, Nilsson, Z. Krebsforsch. Klin. Onkol. 77, 166 (1972). Review of mechanism of action: K. D. Tew, M. E. Stearns, Pharmacol. Ther. 43, 299-319 (1989); of pharmacokinetics and pharmacodynamics: A. T. Bergenheim, R. Henriksson, Clin. Pharmacokinet. 34, 163-172 (1998).
Properties: Crystals from benzene-petr ether, mp 104-105°. [a]D20 +50° (in dioxane). uv max (alcohol): 270.7, 276.5 nm.
Melting point: mp 104-105°
Optical Rotation: [a]D20 +50° (in dioxane)
Absorption maximum: uv max (alcohol): 270.7, 276.5 nm
Derivative Type: 17-Phosphate
Trademarks: Estracyt (Pfizer)
Molecular Formula: C23H32Cl2NO6P
Molecular Weight: 520.38
Percent Composition: C 53.09%, H 6.20%, Cl 13.63%, N 2.69%, O 18.45%, P 5.95%
Properties: mp 155° (dec). [a]D20 +30° (dioxane). Sol in aqueous and alkali solns.
Melting point: mp 155° (dec)
Optical Rotation: [a]D20 +30° (dioxane)
Derivative Type: 17-(Dihydrogenphosphate) disodium salt monohydrate
CAS Registry Number: 52205-73-9 (anhydrous)
Trademarks: Emcyt (Pfizer)
Molecular Formula: C23H30Cl2NNa2O6P.H2O
Molecular Weight: 582.36
Percent Composition: C 47.44%, H 5.54%, Cl 12.18%, N 2.41%, Na 7.90%, O 19.23%, P 5.32%
Properties: Off-white powder; readily sol in water.
Therap-Cat: Antineoplastic.
Keywords: Antineoplastic; Alkylating Agents; Nitrogen Mustards.
Estriol Estrone Etafedrine Etafenone Etamiphyllin

Systematic (IUPAC) name
(17β)-17-Hydroxyestra-1(10),2,4-trien-3-yl bis(2-chloroethyl)carbamate
Clinical data
Trade names Emcyt
AHFS/ monograph
MedlinePlus a608046
Licence data US FDA:link
Pregnancy cat. D (AU) X (US)
Legal status Prescription Only (S4) (AU) -only (CA) POM (UK) -only (US)
Pharmacokinetic data
Bioavailability 75%[1]
Metabolism Hepatic to estradiol and estrone[1]
Half-life 15-24 hours[1]
Excretion Faeces (2.9-4.8%)[1]
CAS number 2998-57-4 YesY
ATC code L01XX11
PubChem CID 259331
DrugBank DB01196
ChemSpider 227635 YesY
UNII 35LT29625A YesY
KEGG D04066 YesY
Chemical data
Formula C23H31Cl2NO3 
Mol. mass 440.403 g/mol
 YesY (what is this?)  (verify)

Estramustine (Emcyt, Estracit) is a antimicrotubule chemotherapy agent used to treat prostate cancer. It is a derivative of oestrogen (specifically, estradiol) with a nitrogen mustard-carbamate ester moiety. It has been withdrawn from a number of markets (Australia, Brazil, Ireland and Norway).[2]