Ultram etc. (tramadol) is an atypical opioid analgesic used to treat moderate to moderately severe pain.
Approved in the U.S. in 1995, studies have shown that tramadol causes fewer side effects like constipation and respiratory depression than conventional opioids and has a low potential for abuse or addiction. Tramadol has a short half-life which necessitates dosing of immediate-release formulations every 4 to 6 hours. Although human clinical studies are lacking, there is a great deal of anecdotal evidence that tramadol may be effective as an adjunct treatment for anxiety disorders.
Tramadol not only acts on opioid receptors, but, like SSRI and SSNRI antidepressants, also inhibits serotonin (5-hydroxytryptamine; 5-HT) and noradrenaline (norepinephrine) reuptake. This effect on neurotransmitters may account for tramadol's potential value in treating anxiety disorders.