Altrenogest
[CAS# 850-52-2]

Identification

• Classification: Biochemical >> Inhibitor >> Endocrinology & hormones >> Estrogen/progestogen receptor agonist
• Name: Altrenogest
• Synonyms: (8S,13S,14S,17R)-17-hydroxy-13-methyl-17-prop-2-enyl-1,2,6,7,8,14,15,16-octahydrocyclopenta[a]phenanthren-3-one
• Molecular Formula: C₂₁H₂₆O₂
• Molecular Weight: 310.43
• CAS Registry Number: 850-52-2
• EC Number: 212-703-1
• SMILES: C[C@]12C=CC3=C4CCC(=O)C=C4CC[C@H]3[C@@H]1CC[C@]2(CC=C)O

Properties

• Density: 1.1±0.1 g/cm³ Calc.^*
• Boiling point: 495.6±45.0 °C 760 mmHg (Calc.)^*
• Flash point: 210.1±21.3 °C (Calc.)^*
• Solubility: DMSO 60 mg/mL, Water $lessThan$1 mg/mL (Expl.)
• Index of refraction: 1.594 (Calc.)^*

Safety Data

• Hazard Symbols: GHS06;GHS08;GHS09 Danger
• Risk Statements: H301-H360-H373-H410
• Safety Statements: P203-P260-P264-P270-P273-P280-P301+P316-P318-P319-P321-P330-P391-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	3	H301
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Reproductive toxicity	Repr.	1B	H360
Reproductive toxicity	Repr.	2	H361
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Carcinogenicity	Carc.	2	H351
Reproductive toxicity	Repr.	1A	H360

Discovery and Applications

Altrenogest is a synthetic progestin primarily used in veterinary medicine for the regulation of reproduction in animals, particularly in horses and swine. It was developed in the latter half of the 20th century to provide a reliable means of controlling estrous cycles and improving breeding management.

Chemically, altrenogest is a derivative of progesterone with potent progestogenic activity. Its molecular structure allows it to bind selectively to progesterone receptors in reproductive tissues, thereby mimicking the effects of natural progesterone.

Pharmacologically, altrenogest acts by maintaining a progestational state in the uterus, suppressing estrus (heat) and ovulation. This effect facilitates the synchronization of estrous cycles, allowing for controlled breeding schedules and improved fertility management. Altrenogest’s action involves modulation of the hypothalamic-pituitary-gonadal axis, leading to decreased release of gonadotropins responsible for follicular development and ovulation.

In veterinary practice, altrenogest is commonly administered orally or via feed additives. In mares, it is used to suppress unwanted estrus behavior, prepare the uterus for embryo transfer, and synchronize ovulation in breeding programs. In swine, altrenogest is employed to synchronize estrus in gilts and sows, enhancing reproductive efficiency.

Pharmacokinetically, altrenogest is absorbed rapidly after oral administration and metabolized in the liver. It exhibits a relatively short half-life, which supports its use in daily dosing regimens to maintain steady progestogenic effects. Excretion occurs primarily through urine and feces.

Adverse effects of altrenogest are generally minimal when used according to veterinary guidelines. However, improper handling or exposure to the compound by humans may pose risks due to its hormonal activity, and caution is advised to prevent accidental contact, especially for pregnant women.

Altrenogest’s use has contributed significantly to improved reproductive management in animal husbandry by enabling precise control over breeding cycles. This has led to better planning, higher conception rates, and increased productivity in livestock industries.

In summary, altrenogest is a synthetic progestin used mainly in veterinary medicine to regulate and synchronize estrous cycles in horses and pigs. Its pharmacological action mimics natural progesterone, enabling controlled reproduction management with a well-established safety and efficacy profile in target animal species.

References

1985. Altrenogest and Fat for Summer Breeding of Primiparous Sows. Journal of Animal Science, 61(2).
DOI: 10.2527/jas1985.612480x

2021. Downregulation of testicular function in the goat by altrenogest. BMC Veterinary Research, 17(1).
DOI: 10.1186/s12917-021-02845-6

2024. Enhancement of the solubility and oral bioavailability of altrenogest through complexation with hydroxypropyl-β-cyclodextrin. European Journal of Pharmaceutical Sciences, 194.
DOI: 10.1016/j.ejps.2024.106691