Opioid with monoamine action is?
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).
Tramadol
Pentazocine
Pethidine
Meperidine