Product name Altrenogest
Molecular weight 310.43
Appearance White or white crystalline powder
Melting point 116.0~121.0℃
Loss on drying ≤0.50%
Specific Rotation -67.0°~-77.0°
Related foreign steroids ≤2
Altrenogest is indicated (labeled) to suppress estrus in mares to allow a more predictable occurrence of estrus following withdrawal of the drug. It is used clinically to assist mares to establish normal cycles during the transitional period from anestrus to the normal breeding season often in conjunction with an artificial photoperiod. It is more effective in assisting in pregnancy attainment later in the transition period. One group of authors (Squires et al. 1983) suggest selecting mares with considerable follicular activity (mares with one or more follicles 20 mm or greater in size) for treatment during the transitional phase. Mares that have been in estrus for 10 days or more and have active ovaries are also considered to be excellent candidates for progestin treatment.
Altrenogest is effective in normally cycling mares for minimizing the necessity for estrus detection, for the synchronization of estrus and permitting scheduled breeding. Estrus will ensue 2-5 days after treatment is completed and most mares ovulate between 8-15 days after withdrawal. Altrenogest is also effective in suppressing estrus expression in show mares or mares to be raced. Although the drug is labeled as contraindicated during pregnancy, it has been demonstrated to maintain pregnancy in oophorectomized mares and may be of benefit in mares who abort due to sub-therapeutic progestin levels.
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)