Involves opioid receptor activation and inhibition of serotonin and norepinephrine reuptake*1 pointLidocaineGabapentinKetamineTramadolFlunixin Meglumine

To answer your question, let's analyze the options based on the involvement of opioid receptor activation and the inhibition of serotonin and norepinephrine reuptake.

1. Lidocaine: Primarily a local anesthetic, it works by blocking Na+ channels and has no significant involvement with opioid receptors or serotonin/norepinephrine reuptake.

2. Gabapentin: This drug is used primarily for neuropathic pain and works by inhibiting voltage-gated calcium channels. It does not primarily act on opioid receptors and does not significantly inhibit serotonin or norepinephrine reuptake.

3. Ketamine: Although it has some NMDA receptor antagonism, ketamine primarily acts as an anesthetic and has some effect on opioid receptors. However, its primary actions involve glutamate, not significant serotonin or norepinephrine reuptake inhibition.

4. Tramadol: Tramadol is unique as it has a dual mechanism of action. It acts as a weak μ-opioid receptor agonist and also inhibits the reuptake of serotonin and norepinephrine, making it the strongest candidate for the described actions.

5. Flunixin Meglumine: This is a non-steroidal anti-inflammatory drug (NSAID) and does not interact with opioid receptors nor does it inhibit serotonin and norepinephrine reuptake.

Final Answer

Therefore, Tramadol is the correct choice as it involves opioid receptor activation and inhibits the reuptake of serotonin and norepinephrine.