Nafarelin is an agonist of gonadotropin-releasing hormone (GNRH).1,2,3 It is a long-acting agent that, after an initial increase in sex hormone levels, decreases the level of circulating gonadotropins and sex hormones. In vivo, nafarelin (0.5-2.0 μg/kg, s.c.) reduces plasma levels of luteinizing hormone and testosterone as well as testicular volume, sperm count, sperm motility, and duration of ejaculation in male dogs.1 Nafarelin (32 μg/animal per day) inhibits estrus in female beagle dogs.2 It also reduces the volume of endometrial tissue in a rat model of endometriosis.3 Formulations containing nafarelin have been used in the treatment of endometriosis and central precocious puberty.
1.Vickery, B.H., McRae, G.I., Briones, W.V., et al.Dose-response studies on male reproductive parameters in dogs with nafarelin acetate, a potent LHRH agonistJ. Androl.6(1)53-60(1985) 2.McRae, G.I., Roberts, B.B., Worden, A.C., et al.Long-term reversible suppression of oestrus in bitches with nafarelin acetate, a potent LHRH agonistJ. Reprod. Fertil.74(2)389-397(1985) 3.Mizutani, T., Sakata, M., and Terakawa, N.Effect of gonadotropin-releasing hormone agonists, nafarelin, buserelin, and leuprolide, on experimentally induced endometriosis in the ratInt. J. Fertil. Menopausal Stud.40(2)106-111(1995)