Pharmacotherapeutic Group: prostaglandins and synthetic analogue. ATCvet Code: QG02AD90
Cloprostenol is a synthetic prostaglandin analogue structurally related to Prostaglandin F2α (PGF2α), for use in cattle and horses. As a potent luteolytic agent it causes functional and morphological regression of the corpus luteum (luteolysis) in cattle and horses followed by return to oestrus and normal ovulation.
Note: There is a refractory period of four to five days after ovulation when cattle and horses are insensitive to the luteolytic effect of prostaglandins. Cloprostenol has a good safety margin and does not impair fertility. No deleterious effects have been reported on the progeny conceived at the oestrus following treatment.
Pharmacodynamic properties
Cloprostenol is a synthetic prostaglandin analogue structurally related to Prostaglandin F2α (PGF2α). As a potent luteolytic agent, at dosage of only 500 micrograms, it causes functional and morphological regression of the corpus luteum (luteolysis).
Furthermore, this group of substances has a contractile effect on smooth muscles (uterus, gastrointestinal tract, respiratory tract, vascular system).
Cloprostenol does not demonstrate any androgenic, oestrogenic or anti-progesterone activity and its effects on pregnancy is due to its luteolytic property.
Unlike other prostaglandin analogues, cloprostenol has not tromboxane A2 activity and does not cause platelet aggregation. Cloprostenol has a good safety margin and does not impair fertility. No deleterious effects have been reported on the progeny conceived at the oestrus following treatment.
Pharmacokinetic particulars
Studies of metabolism, using 15-14C-cloprostenol sodium, were conducted in swine and cattle (following I.M. administration) to determine residual levels.
Cloprostenol sodium is rapidly absorbed from the injection site. It is then metabolised and finally excreted practically similarly between urine and stool. In cattle less than 1% of the administered dose is eliminated via milk.
The main pathway of metabolization in all animal species appears to be that of β-oxidation with formation of the Tetranor-or dinor-acids of cloprostenol.
The values at the peak of radioactivity in the blood are observed within 1 hour of parenteral administration of sodium cloprostenol and tend to decrease with a T1/2 between 1 and 3 hours (depending on the animal species).