The active ingredient in a drug used to treat symptoms of advanced prostate cancer. It is also used to treat early puberty in children and certain gynecologic conditions. It is being studied in the treatment of other conditions and types of cancer. Leuprolide blocks the body from making testosterone (a male hormone) and estradiol (a female hormone). It may stop the growth of prostate cancer cells that need testosterone to grow. It is a type of gonadotropin-releasing hormone analog.