What Is Deslorelin?
Deslorelin acetate is a potent synthetic gonadotropin-releasing hormone (GnRH) analogue.1 According to the literature, the advantage to using deslorelin over hCG to induce ovulation is that it possesses a smaller molecular weight than hCG, making it less antigenic and reducing the chance that antibody resistance will be developed against it after multiple administrations in a season.
Manufactured as an implant that releases the drug continually for about 72 hours, it is also available in injectable form that allows between 16 to 21 hours of activity.2 The primary uses of deslorelin are in stimulating the hormones which facilitate the breeding of mares at an optimal time, leading to a higher rate of successful pregnancy, and in non-pregnant broodmares for the management of their heat cycle.
The literature suggests that prior to administration, it should be determined by rectal palpation and/or ultrasonography that the cyclic estrous mare has an ovarian follicle between 30 and 40 mm in diameter. Effectiveness is contingent upon accurate diagnosis of estrus and detection of a developing follicle between 30 and 40 mm in diameter.
"Two hundred eighty three (283) mares, ranging in age from 2 to 20 years (mean 10.6 years) of age randomly received either deslorelin or placebo after the presence of an ovarian follicle between 30 and 40 mm in diameter was confirmed. All 283 mares were evaluated for field safety under actual conditions of use. A total of 191 mares (97 placebo and 94 mares in the deslorelin group) were evaluated for effectiveness over a total of 273 cycles (131 placebo and 142 deslorelin cycles). Breeds included Standardbreds, Thoroughbreds, Quarter Horses and Paints. Mares were evaluated for up to 3 cycles to determine if deslorelin induced ovulation in cycling mares, and to determine the effects on the interovulatory interval, pregnancy rate and general health characteristics of the resultant foals.
"The proportion of mares ovulating within 48 hours of treatment was significantly higher in the deslorelin group as compared to the placebo group."3
While deslorelin has enjoyed growing popularity as an aid in follicular maturation and ovulation, the available literature does cite a wider range of side effects in the utilization of the implant version of deslorelin, which is not the case for the injectable form.
However, it must be noted that administration of deslorelin implants in a small percentage of mares does result in a prolonged interovulatory interval due to down-regulation of the pituitary by the continued release of deslorelin from the implant after ovulation has occurred.14–16 This down-regulation is most pronounced when prostaglandins are administered early in diestrus after the administration of deslorelin, compared with mares that are allowed to return to estrus naturally. This side effect can be avoided by removing the implant after ovulation has occurred.1
FDA-approved for use in equines, deslorelin does not manipulate the timing of ovulation, but rather aids in follicular maturation and ovulation. Deslorelin in injectable form is available in several branded versions. It is also available in combination with hCG, which provides the benefits of hCG without the diminishing effectiveness of hCG over time.
About NexGen Pharmaceuticals
NexGen Pharmaceuticals is an industry-leading veterinary compounding pharmacy, offering sterile and non-sterile compounding services Nationwide. Unlike other veterinary compounding pharmacies, NexGen focuses on drugs that are difficult to find or are no longer available due to manufacturer discontinuance or have yet to be offered commercially for veterinary applications, but which still serve a critical need for our customers. We also specialize in wildlife pharmaceuticals, including sedatives and their antagonists, offering many unique options to serve a wide array of zoo animal and wildlife immobilization and anesthesia requirements.
Our pharmacists are also encouraged to develop strong working relationships with our veterinarians in order to better care for veterinary patients. Such relationships foster an ever-increasing knowledge base upon which pharmacists and veterinarians can draw, making both significantly more effective in their professional roles.