Tramadol is an opioid used as an analgesic for treating moderate to severe pain. It is a synthetic agent, unrelated to other opioids, and appears to have actions on the GABAergic, noradrenergic and serotonergic systems. Tramadol was developed by the German pharmaceutical company Grünenthal GmbH and marketed under the trade name Tramal®. Grünenthal has also cross licensed the drug to many other pharmaceutical companies that market it under various names, some of which are listed below.