Melengestrol acetate (MLGA), sold under the brand names Heifermax and MGA among others, is a progestin medication which is used in animal reproduction.[1][2] It is not approved for use in humans, and is instead used as an implantable contraceptive for captive animals in zoos and other refuges,[3] and is also used as a feed additivetopromote growthincattle, a purpose it is licensed for in the United States and Canada.[4]
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| Trade names | Heifermax, MGA |
| Other names | MGA; MLA; MLGA; Melengesterol acetate; Methylsuperlutin; U-21240; BDH-1921; 17α-Acetoxy-16-methylene-6-methyl-6-dehydroprogesterone; 17α-Acetoxy-16-methylene-6-methylpregna-4,6-diene-3,20-dione |
| Drug class | Progestogen; Progestin; Progestogen ester |
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| ECHA InfoCard | 100.018.964  |
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| Formula | C25H32O4 |
| Molar mass | 396.527 g·mol−1 |
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MLGA is used in animal reproduction.[3][4]
MLGA is a progestogen, and hence is an agonist of the progesterone receptor.[5] It has been found to possess 73% of the affinityofprogesterone for the progesterone receptor in rhesus monkey uterus.[5]
MLGA, also known as 17α-acetoxy-16-methylene-6-dehydro-6-methylprogesterone or as 17α-acetoxy-16-methylene-6-methylpregna-4,6-diene-3,20-dione, is a synthetic pregnane steroid and a derivativeofprogesterone.[1][2] It is specifically a derivative of 17α-hydroxyprogesterone with a methyl group at the C6 position, a methylene group at the C16 position, a double bond between the C6 and C7 positions, and an acetate ester at the C17α position.[1][2] As such, it is also a derivative of 16-methylene-17α-hydroxyprogesterone acetate. MLGA is the acetate esterofmelengestrol, which in contrast, has never been marketed.[1] Analogues of MLGA include other 17α-hydroxyprogesterone derivatives such as chlormadinone acetate, chlormethenmadinone acetate, cyproterone acetate, delmadinone acetate, hydroxyprogesterone caproate, medroxyprogesterone acetate, megestrol acetate, methenmadinone acetate, and osaterone acetate.[1] The only structural difference between MLGA and megestrol acetate is the presence of the C16 methylene group in the former.[1]
Melengestrol acetate is the generic name of the drug and its USANTooltip United States Adopted Name and USPTooltip United States Pharmacopeia.[1][2] Melengestrol is the INNTooltip International Nonproprietary Name and BANTooltip British Approved Name of the unesterified free alcohol form.[1][2]
MLGA is marketed under the brand names Heifermax and MGA among others.[1][2]