Pharmacotherapeutic group: Sex hormones and modulators of the genital system, progestagens.
ATCvet code: QG03DX90
Pharmacodynamic properties
Altrenogest has a similar action to the natural hormone progesterone. When administered orally it suppresses the normal sexual cycle, preventing signs of heat and ovulation. Withdrawal then allows the natural hormones to be released again and animals return to heat in a synchronised fashion.
Altrenogest is a synthetic trienic C21 steroidal progestagen, belonging to the 19-nor-testosterone series. It is an orally active progestagen. Altrenogest decreases blood concentrations of the endogenous gonadotrophins, LH and FSH. As a consequence, it induces the regression of all large follicles (>20-25 mm) and therefore blocks oestrus or ovulation. During the second half of the treatment period with the product, when all large follicles have regressed, there is a peak in FSH concentration which initiates a new wave of follicular growth. End of treatment is followed by a steady rise in LH concentration, which sustains follicular growth and maturation.
Pharmacokinetic properties
Altrenogest is rapidly absorbed following oral administration. Altrenogest is extensively metabolised in the liver. Altrenogest is eliminated both via bile in faeces and via urine.