Definition

A sustained-release (SR) injectable microsphere formulation composed of the acetate salt of leuprolide, a synthetic, long-acting nonapeptide analog of the endogenous hormone gonadotropin-releasing hormone (GnRH), with potential antineoplastic activity. Upon administration, leuprolide binds to and activates the gonadotropin-releasing hormone receptor (GnRHR). The continuous stimulation of GnRHR by leuprolide results in both the desensitization of pituitary GnRHR and the inhibition of pituitary secretion of the gonadotropins follicle stimulating hormone (FSH) and luteinizing hormone (LH). In females, prolonged administration results in a decrease in estradiol production and suppression of ovarian function. Leuprolide also reduces testosterone production to castration levels and may inhibit androgen receptor-positive tumor progression.