Methadone is a long-acting synthetic opioid analgesic and a potent agonist at the mu-opioid receptor. It is used primarily for two purposes: as a maintenance therapy for opioid dependence and as a pain management solution for chronic pain. First synthesized in Germany in the 1930s, methadone has since become an essential medication in the treatment of opioid addiction and pain management.

Methadone dosing must be carefully individualized due to its variable pharmacokinetics and potential for accumulation. Initial doses for opioid dependence treatment are usually 20-30 mg per day, with adjustments based on patient response and withdrawal symptoms. Maintenance doses typically range from 60-120 mg per day.