Altrenogest;Allyltrienolone

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Altrenogest, sold under the brand names Regumate and Matrix, is a progestin of the 19-nortestosterone group which is widely used in veterinary medicine to suppress or synchronize estrus in horses and pigs.It is available for veterinary use in both Europe (as Regumate) and the United States (as Matrix).

Pharmacology

An in vitro yeast structure-activity relationships bioassay study found that altrenogest was the most potent agonist of both the progesterone receptor (PR) and the androgen receptor (AR) of a large selection of other progestogens as well as anabolic-androgenic steroids (AAS).The observed potency of altrenogest even exceeded that of metribolone (methyltrienolone, R-1881), which was the second most potent compound.In the study, it showed an EC₅₀ of 0.64 nM for the AR and 688% of the relative activational potency of testosterone and an EC₅₀ of 0.3 nM and 1,300% of the relative activational potency of progesterone, with an AR/PR activational potency ratio of 0.53.

Although very potent in both activities in vitro, the AR/PR activational potency ratio of altrenogest was in the same range as that of other 19-nortestosterone progestins such as norethisterone, noretynodrel, norgestrel, and allylestrenol (ratio for all < 1.0), whereas the AR/PR activational potency ratio of its 17α-deallylated AAS analogue trenbolone was, at 64, profoundly increased (although the ratio of metribolone (the 17α-methylated variant of altrenogest), at 0.56, was almost the same as that of altrenogest).

According to its manufacturer Roussel Uclaf, altrenogest has weak anabolic and androgenic activity equivalent to 1/20th of that of testosterone.However, no significant androgenic effects have been observed in young stallions or mature mares,and altrenogest has notably been used to maintain pregnancy in mares (similarly to the use of allylestrenol to maintain pregnancy in women) with no incidence of virilization or other abnormalities in filly offspring.On the other hand, minor potential anabolic/androgenic effects have been suggested for altrenogest in pigs.

Altrenogest

Clinical data
Trade names	Regumate, Matrix
Synonyms	Allyltrenbolone; Allyltrienolone; RU-2267; RH-2267; A-35957; A-41300; 17α-Allylestra-4,9,11-trien-17β-ol-3-one; 17α-Allyl-19-nor-δ9,11-testosterone
Routes of administration	By mouth[1]
Drug class	Progestin; Progestogen
ATCvet code	QG03DX90 (WHO)
Identifiers
IUPAC name[show]
CAS Number	850-52-2
PubChem CID	10041070
ChemSpider	8216634
UNII	2U0X0JA2NB
KEGG	D02840
ChEMBL	CHEMBL1315492
ECHA InfoCard	100.011.549
Chemical and physical data
Formula	C21H26O2
Molar mass	310.430 g/mol