Isopregnanolone

Isopregnanolone
Names
	IUPAC name 3β-Hydroxy-5α-pregnan-20-one
	Systematic IUPAC name 1-[(1S,3aS,3bR,5aS,7S,9aS,9bS,11aS)-7-Hydroxy-9a,11a-dimethylhexadecahydro-1H-cyclopenta[a]phenanthren-1-yl]ethan-1-one
	Other names Isoallopregnanolone; Epiallopregnanolone; Sepranolone; 3β,5α-Tetrahydroprogesterone; 3β,5α-THP
Identifiers
CAS Number	516-55-2 ;
3D model (JSmol)	Interactive image;
ChemSpider	83761;
ECHA InfoCard	100.007.478
PubChem CID	92787;
UNII	3P8Z6V53MU ;
CompTox Dashboard (EPA)	DTXSID001023710 ;
	InChI InChI=1S/C21H34O2/c1-13(22)17-6-7-18-16-5-4-14-12-15(23)8-10-20(14,2)19(16)9-11-21(17,18)3/h14-19,23H,4-12H2,1-3H3/t14-,15-,16-,17+,18-,19-,20-,21+/m0/s1 Key: AURFZBICLPNKBZ-FZCSVUEKSA-N; InChI=1/C21H34O2/c1-13(22)17-6-7-18-16-5-4-14-12-15(23)8-10-20(14,2)19(16)9-11-21(17,18)3/h14-19,23H,4-12H2,1-3H3/t14-,15-,16-,17+,18-,19-,20-,21+/m0/s1 Key: AURFZBICLPNKBZ-FZCSVUEKBS;
	SMILES CC(=O)[C@H]1CC[C@@H]2[C@@]1(CC[C@H]3[C@H]2CC[C@@H]4[C@@]3(CC[C@@H](C4)O)C)C;
Properties
Chemical formula	C21H34O2
Molar mass	318.49 g/mol
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Isopregnanolone, also known as isoallopregnanolone and epiallopregnanolone, as well as sepranolone (INNTooltip International Nonproprietary Name), and as 3β-hydroxy-5α-pregnan-20-one or 3β,5α-tetrahydroprogesterone (3β,5α-THP), is an endogenous neurosteroid and a natural 3β-epimer of allopregnanolone.^[1]^[2] It has been reported to act as a subunit-selective negative allosteric modulator of the GABA_A receptor,^[2] and antagonizes in animals and humans some but not all of the GABA_A receptor-mediated effects of allopregnanolone, such as anesthesia,^[3] sedation,^[4] and reduced saccadic eye movements,^[4] but not learning impairment.^[2] Isopregnanolone has no hormonal effects and appears to have no effect on the GABA_A receptor by itself; it selectively antagonizes allopregnanolone and does not affect the effects of other types of GABA_A receptor positive allosteric modulators such as benzodiazepines or barbiturates.^[1]^[5]

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Isopregnanolone is synthesized from progesterone in the body by the actions of the enzymes 5α-reductase and 3β-hydroxysteroid dehydrogenase (with 5α-dihydroprogesterone as the intermediate in this two-step transformation)^[6] and can be reversibly metabolized into allopregnanolone by the enzyme 3α-hydroxysteroid dehydrogenase.^[1]^[2] Levels of isopregnanolone, progesterone, and allopregnanolone are highly correlated across the menstrual cycle and throughout pregnancy.^[1] The concentrations of isopregnanolone are significantly less than those of progesterone and allopregnanolone; about half of those of allopregnanolone, to be precise.^[6] Isopregnanolone has a relatively long serum elimination half-life of 14 hours in humans.^[1]

Isopregnanolone (developmental code name UC-1010) is under development for the treatment of premenstrual dysphoric disorder.^[7]^[8] As of 2017, it is in phase II clinical trials for this indication.^[7]^[8]

See also