Opana ER (Extended Release) is a opioid medication primarily used for the management of moderate to severe chronic pain that requires round-the-clock treatment. It contains oxymorphone, a strong opioid analgesic, and is designed for long-lasting pain relief over an extended period. Opana ER is often prescribed when other pain relief medications are insufficient or not effective in managing severe pain, such as pain following surgery, injury, or certain medical conditions like cancer.