An analgesic 'X' acts through opioid as well as additional spinal monoaminergic mechanisms. Which of the following can be 'X'?
-Tramadol and tapendadol have additional analgesic mechanisms apa from activation of opioid receptors. -These drugs increase release of serotonin in spinal cord and strengthen the descending inhibitory pathway.
Tramadol
Etioheptazine
Dextropropoxyphene
Alfentanil
CNS