REGU-MATE® (altrenogest) Oral Solution
Manufacturer – Hoechst-Roussel
Product information – Regu-mate®, marketed for short-term estrus suppression in domestic horses, has been used for aggression control in male Pzrewalski horses and for contraception in suids and some marine mammals. Tapirs have also been treated with Regu-mate®, however the standard horse dose may not be effective in all individuals.
Safety to humans - Protective gloves should be worn during administration, since it is readily absorbed through skin and can cause disruption of menstrual cycles and prolongation of pregnancy in humans.
Latency to effectiveness - As with implants and injections, separation or alternative contraception should be used for 1-2 weeks post initiation of product.
Estrous cycles during contraceptive treatment - Synthetic progestins may effect contraception by blocking ovulation, causing thickening of cervical mucus, slowing ovum transport, and/or interfering with fertilization or implantation. However, follicle growth may continue and sometimes be accompanied by estrogen production sufficient to cause estrous behavior. Ovulation may occur even though pregnancy does not ensue. Higher progestin doses may be preferred, so that estrous behavior is prevented, but may not be effective in completely suppressing follicle growth and all estradiol production.
Duration of efficacy and reversibility - Duration of efficacy may not be much more than one day, so must be administered daily. Following cessation of treatment, rapid clearance can result in ovulation within a few days, but actual latency to conception will vary by individual.
Use during pregnancy - Progestins are not recommended in pregnant animals because of the possibility of prolonged gestation, stillbirth, abortion, etc. in some species, although the effect may depend on dose. Progestins in late pregnancy seem not to interfere with parturition in primates, but this may be a taxon-specific phenomenon.
Use during lactation - Progestins are sometimes prescribed for lactating women and are considered generally safe for nursing infants.
Use in pre-pubertals or juveniles – Future reproduction was not affected in calves of domestic cows on MGA-treated feed, but no studies of pre-pubertal treatment with MGA or other progestins have been conducted with other species, so possible long-term effects on fertility are not known.
Consideration for seasonal breeders - Treatment should begin at least one month before the anticipated onset of the breeding season.
Precautions – Progestins likely cause weight gain in all species. Regu-mate® has caused endometritis in domestic horses and cystic follicles in suids at low doses. Possible deleterious effects on uterine and mammary tissues vary greatly by species; see cautions for each taxon.
Reporting requirements - All institutions using Regu-mate® are asked to complete a Contraception Survey for the AZA Reproductive Management Center. It is essential that accurate records of doses and intervals be maintained and results reported to the Reproductive Management Center's Contraception Database to contribute to dosage development.
For questions about the Contraception Survey, contact:
Ashley Franklin, Program Analyst
AZA Reproductive Management Center
Saint Louis Zoo
1 Government Drive
St. Louis, MO 63110
314-646-4732; fax: 314-646-5534