Therapeutic Review Leuprolide Acetate

Leuprolide acetate is a potent Gonadotropin Releasing Hormone (GnRH) agonist. The general premise behind leuprolide is that it inhibits the synthesis of lutenizing hormone and follicle stimulating hormone via a negative feedback. By reducing the production of these hormones, the drug effectively reduces estrogen and androgen production. This compound has been formulated as a depot formulation (1-, 3and 4-month) to provide long-term treatment for reproductive diseases in humans, including mammary and prostatic cancer, endometriosis, and precocious puberty.1 In these formulations, the hydrophilic leuprorelin is held in biodegradable highly lipophilic synthetic polymer microspheres.2 The depot is released over a defined length of time depending on the polymer. In humans, peak plasma concentrations can occur rapidly (1-3 hours) following a subcutaneous injection, and the microspheres help maintain plasma concentrations (1-month depot) between 0.4 to 1.4 g/L for almost a month.2 The long-term use of this drug in humans has been found to desensitize the pituitary. Leuprolide acetate is not recommended during pregnancy, as it can cause fetal abnormalities. Although formulated for humans, leuprolide acetate has been used fairly extensively in exotic and avian species. In exotic animal practice, this compound is primarily used to manage adrenal gland disease in ferrets and excessive egg laying in psittacines. However, this compound has also been used to induce molting in chickens, stimulate rat spermatogenesis, and serve as a reversible contraceptive in wapiti (Cervus elaphus nelsoni).3-5 The author also has some anecdotal success using leuprolide acetate (0.15 mg/kg q 4 weeks) as a method of reducing aggression in intact male green iguanas (Iguana iguana). Because the husbandry methods used to manage captive exotic species have improved over the past decade, many of these animals are living longer and successfully reproducing. These captive successes have led to the development of new and challenging health crises for the veterinarian to manage. The purpose of this article is to provide a