<prompt> Opioid with monoamine action is?TramadolPentazocinePethidineMeperidine  <response>: Ans. is a i.e., Tramadol Unlike other opioids, tramadol inhibits reuptake of NA and 5-HT and thus activates monoaminergic spinal inhibition of pain -- action can be abolished by 5-HT3 antagonist ondansetron. 