Short answers, pulled from the story.
Analgesics are drugs used specifically for pain management, while anesthetics temporarily reduce or eliminate sensation more broadly. The two categories are neurophysiologically overlapping, and various drugs have both analgesic and anesthetic effects.
Most drugs in the COX-2 inhibitor class were found to increase the risk of cardiovascular events by 40% on average after widespread adoption. Rofecoxib and valdecoxib were withdrawn from the market as a result, while warnings were added to other drugs in the class.
Opioid-induced hyperalgesia is a condition in which exposure to opioids increases a patient's sensitivity to pain and can make non-painful stimuli feel painful, a response called allodynia. Opioid tolerance is a separate phenomenon in which frequent opioid use leads to diminished pain relief, requiring higher doses to maintain the same effect.
Neuropathic pain is commonly treated with drugs not normally classified as analgesics, including tricyclic antidepressants such as amitriptyline and anticonvulsants such as gabapentin and pregabalin. The anticonvulsant carbamazepine is also used for neuropathic pain.
Tramadol is structurally closer to venlafaxine than to codeine. It works through mild agonism of the mu opioid receptor but also acts as a weak serotonin releasing agent and norepinephrine reuptake inhibitor, giving it a dual mechanism of action distinct from classic opioids.
Ziconotide is a blocker of N-type voltage-gated calcium channels administered intrathecally for the relief of severe pain, usually cancer-related. It is delivered directly into the fluid surrounding the spinal cord because of its specialized application.