Chemistry - A synthetic analogue of prostaglandin Falpha, fluprostenol sodium occurs as a white or almost white hygroscopic powder that is soluble in water and alcohol. The drug’s potency is expressed in terms of fluprostenol; 52.4 micrograms of fluprostenol sodium is equivalent to 50 micrograms of fluprostenol.
Storage/Stability/Compatibility - Fluprostenol should be stored in airtight containers and protected from light. The manufacturer recommends discarding any unused product after opening the vial.
Pharmacology - Fluprostenol exhibits pharmacologic effects similar to those of the other agents in this class. Effects on the female reproductive system include stimulation of myometrial activity, relaxation of the cervix, inhibition of steroidogenesis by corpora lutea, and potential lysing of corpora lutea. Fluprostenol reportedly has less smooth muscle stimulant activity and, therefore, may be safer to use to induce parturition in the mare.
Uses/Indications - The labeled indications for fluprostenol are to synchronize estrus for breeding management and for postpartum breeding. Suggested therapeutic uses by the manufacturer include: induction of luteolysis following early fetal death and resorption; termination of persistent diestrus; termination of pseudopregnancy; termination of lactational anestrus; establishing estrous cycles in barren/maiden mares; and to determine if a mare is cycling. The drug has also been used as an induction agent for parturition and as an abortifacient.
Pharmacokinetics - No information was located for this agent.
Contraindications/Precautions - Fluprostenol should not be used in pregnant mares unless parturition induction or abortion is desired. It should also not be used in mares with acute or sub-acute disorders of the GI tract or respiratory disease.
The manufacturer states that mares receiving non-steroidal antiinflammatory drugs should not receive fluprostenol, as this drug can inhibit the synthesis and release of prostaglandins. The clinical significance of such an interaction is in doubt, however.
The manufacturer recommends conducting a through breeding exam prior to the use of this drug.
Adverse Effects/Warnings - In horses, sweating, increased respiration, mild abdominal discomfort, uneasiness and defecation may be seen after fluprostenol injection. Adverse effects are more likely at doses above those recommended by the manufacturer.
See the warnings regarding the handling of the agent under Client Information below.
Overdosage - No specific information was located. It would be expected that mild overdoses would result in the adverse effects listed above (sweating, diarrhea, increased respiratory rate). The animal should be treated supportively if necessary.
Drug Interactions - Other oxytocic agents’ activity may be enhanced by fluprostenol. Reduced effect of fluprostenol would be expected with concomitant administration of a progestin.
Manufacturer’s suggested dosage for all labeled indications (see above or package insert):
a) 0.55 micrograms/kg (average dose 250 micrograms or 5 ml) IM
To induce parturition in the mare:
a) 2.2 micrograms/kg (0.0022 mg/kg) IM; delivery generally occurs in about 4 hours (Carleton and Threlfall 1986)
b) Pony mares 250 micrograms IM, full-sized mares 1000 micrograms IM. First stage of labor ensues in 30 minutes, onset of second stage labor occurs in about 1/2 -3 hours. Duration of second stage labor varies from about 5-35 minutes. Author recommends further studies before recommending procedure. (Hillman 1987)
As an abortifacient:
a) Prior to the 12th day of pregnancy: 250 micrograms IM (Lofstedt 1986)
b) Prior to day 35 of gestation: 250 micrograms IM one time; after day 35: 250 micrograms IM daily for 3-5 days are required. (Squires and McKinnon 1987)
For estrus synchronization in normally cycling mares:
a) Two injection method: On day 1 give 250 micrograms (Note: The text from this reference reads: 0.250 micrograms; it is believed that this is an error as the manufacturer’s recommended dose is approximately 250 micrograms) and again on day 16. Most (60%) mares will begin estrus 4 days after the second injection and about 90% will show estrous behavior by the 6th day after the second injection. Breed using AI every second day during estrus or inseminated at predetermined times without estrus detection. Alternatively, an IM injection of HCG (2500-3300 Units) can be added on the first or second day (usually day 21) of estrus to hasten ovulation. Breed using AI on days 20, 22, 24, and 26. This may be of more benefit when used early in the breeding season. (Bristol 1987)
Client Information - Fluprostenol should only be used by individuals familiar with its use and precautions. Pregnant women, asthmatics or other persons with bronchial diseases should handle this product with extreme caution. Any accidental exposure to skin should be washed off immediately using soap and water.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times -
Fluprostenol sodium for Injection, equivalent to 50 micrograms/ml fluprostenol in 5 ml vials; Equimate® (Bayer); (Rx) Approved for use in horses. It is not for use in horses intended for food.
Human-Approved Products: None
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