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Norethandrolone
Clinical data
Trade names	Nilevar, Pronabol
Other names	Noretandrolone; CB-8022; 3-Ketoethylestrenol; Ethylestrenolone; 17α-Ethyl-19-nortestosterone; 17α-Ethylestr-4-en-17β-ol-3-one; 17α-Ethyl-19-norandrost-4-en-17β-ol-3-one; Ethylnandrolone; Ethylnortestosterone
AHFS/Drugs.com	International Drug Names
Routes of; administration	By mouth
Drug class	Androgen; Anabolic steroid; Progestin; Progestogen
ATC code	A14AA09 (WHO) ;
Legal status
Legal status	BR: Class C5 (Anabolic steroids); CA: Schedule IV; US: Schedule III;
Identifiers
	IUPAC name (8R,9S,10R,13S,14S,17S)-17-ethyl-17-hydroxy-13-methyl-1,2,6,7,8,9,10,11,12,14,15,16-dodecahydrocyclopenta[a]phenanthren-3-one;
CAS Number	52-78-8 ;
PubChem CID	5858;
ChemSpider	5649 ;
UNII	P7W01638W6;
KEGG	D07127 ;
CompTox Dashboard (EPA)	DTXSID0023379 ;
ECHA InfoCard	100.000.140
Chemical and physical data
Formula	C20H30O2
Molar mass	302.458 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES O=C4\C=C3/[C@@H]([C@H]2CC[C@]1([C@@H](CC[C@@]1(O)CC)[C@@H]2CC3)C)CC4;
	InChI InChI=1S/C20H30O2/c1-3-20(22)11-9-18-17-6-4-13-12-14(21)5-7-15(13)16(17)8-10-19(18,20)2/h12,15-18,22H,3-11H2,1-2H3/t15-,16+,17+,18-,19-,20-/m0/s1 ; Key:ZDHCJEIGTNNEMY-XGXHKTLJSA-N ;
	(verify)

Norethandrolone, sold under the brand names Nilevar and Pronabol among others, is an androgen and anabolic steroid (AAS) medication which has been used to promote muscle growth and to treat severe burns, physical trauma, and aplastic anemia but has mostly been discontinued.^[2]^[3]^[4] It is still available for use in France however.^[3]^[4] It is taken by mouth.^[3]

Side effects of norethandrolone include symptoms of masculinization like acne, increased hair growth, voice changes, and increased sexual desire.^[3] It can also cause estrogenic effects like fluid retention, breast tenderness, and breast enlargement in men and liver damage.^[3] The drug is a synthetic androgen and anabolic steroid and hence is an agonist of the androgen receptor (AR), the biological target of androgens like testosterone and dihydrotestosterone (DHT).^[3]^[5] It has strong anabolic effects relative to its androgenic effects.^[3] The drug also has strong progestogenic effects.^[3]

Norethandrolone was discovered in 1953 and was introduced for medical use in 1956.^[6]^[7] It was the first AAS with a favorable separation of anabolic and androgenic effect to be marketed.^[7]^[8] The drug was mostly withdrawn in the 1980s due to concerns of liver damage.^[9] In addition to its medical use, norethandrolone has been used to improve physique and performance.^[3] The drug is a controlled substance in many countries and so non-medical use is generally illicit.^[3]

Medical uses

Norethandrolone has been used in the treatment of muscle wasting,^[9] patients with severe burns, after severe trauma, and for certain forms of aplastic anemia among other indications.^[3]

Side effects

Side effects of norethandrolone include virilization among others.^[3] It has estrogenic effects and can cause gynecomastia and fluid retention.^[3] As with all 17α-alkylated AAS, long-term use of norethandrolone in high doses may result in hepatotoxicity including elevated liver enzymes and cirrhosis.^[10]

Pharmacology

Pharmacodynamics

v
t
e
Androgenic vs. anabolic activity ratio
of androgens/anabolic steroids
Medication	Ratio^a
Testosterone	~1:1
Androstanolone (DHT)	~1:1
Methyltestosterone	~1:1
Methandriol	~1:1
Fluoxymesterone	1:1–1:15
Metandienone	1:1–1:8
Drostanolone	1:3–1:4
Metenolone	1:2–1:30
Oxymetholone	1:2–1:9
Oxandrolone	1:3–1:13
Stanozolol	1:1–1:30
Nandrolone	1:3–1:16
Ethylestrenol	1:2–1:19
Norethandrolone	1:1–1:20
Notes: In rodents. Footnotes: ^a = Ratio of androgenic to anabolic activity. Sources: See template.

Norethandrolone is an androgen and anabolic steroid and hence is an agonist of the androgen receptor, the biological target of androgens like testosterone and dihydrotestosterone.^[3] It has a high ratio of anabolic to androgenic activity.^[3] Analogously to the case of nandrolone and 5α-dihydronandrolone, 5α-dihydronorethandrolone, the 5α-reduced metabolite of norethandrolone, shows diminished affinity for the androgen receptor relative to norethandrolone.^[3]^[11] This is likely related to the high ratio of anabolic to androgenic activity observed with norethandrolone.^[3]^[11] Norethandrolone has relatively high estrogenic activity via transformation by aromatase into the potent estrogen ethylestradiol.^[3] It also has strong progestogenic activity.^[3] The progestogenic potency of norethandrolone is similar to that of norethisterone in terms of endometrial changes in women.^[12] In addition, norethandrolone is hepatotoxic.^[3]

v
t
e
Relative affinities of nandrolone and related steroids at the androgen receptor
Compound	rAR (%)	hAR (%)
Testosterone	38	38
5α-Dihydrotestosterone	77	100
Nandrolone	75	92
5α-Dihydronandrolone	35	50
Ethylestrenol	ND	2
Norethandrolone	ND	22
5α-Dihydronorethandrolone	ND	14
Metribolone	100	110
Sources: See template.

Pharmacokinetics

The pharmacokinetics of norethandrolone have been reviewed.^[13]

Chemistry

Norethandrolone, also known as 17α-ethyl-19-nortestosterone or as 17α-ethylestr-4-en-17β-ol-3-one, is a synthetic estrane steroid and a 17α-alkylated derivative of testosterone and 19-nortestosterone (nandrolone).^[2]^[3] It is closely related to normethandrone (17α-methyl-19-nortestosterone) and to ethylestrenol (3-deketo-17α-ethyl-19-nortestosterone).^[2]^[3]

Synthesis

Chemical syntheses of norethandrolone have been published.^[13]

History

Norethandrolone was synthesized at G. D. Searle & Company in 1953 and was originally studied as a progestin, along with norethisterone and noretynodrel, but ultimately was not marketed as such.^[6] In 1955, it was re-examined for testosterone-like activity and was found to have similar anabolic activity to testosterone but only one-sixteenth the androgenic potency.^[6]^[9] Norethandrolone was introduced for medical use as an AAS in 1956 and was the first so-called "anabolic steroid", or AAS with a favorable separation of anabolic and androgenic effect, to be marketed.^[7]^[8] It was followed by normethandrone as a progestin in 1957 and by the more well-known AAS nandrolone phenylpropionate in 1959.^[14]^[8] Norethandrolone was introduced in the United States in the late 1950s under the brand name Nilevar but was discontinued in this country in the 1960s due to limited sales.^[3] Although it was also introduced into Europe and certain other markets,^[3] it was withdrawn in many countries in the 1980s due to concerns of cholestatic jaundice.^[9] Today, the drug remains available only in France.^[3]^[4]

Society and culture

Generic names

Norethandrolone is the generic name of the drug and its INNTooltip International Nonproprietary Name and BANTooltip British Approved Name.^[2]^[4] It has also been referred to as noretandrolone, ethylnandrolone, and ethylnortestosterone, as well as by its developmental code name CB-8022.^[2]^[4]