How does ketamine contribute to pain management, and what are key safety concerns?

• A. Opioid receptor agonism
• B. Local sodium channel blockade
• C. NMDA receptor antagonism reduces central sensitization; concerns include dissociation, hypertension, psychotomimetic effects
• D. GABA receptor agonism

Answer: (C)

Ketamine helps manage pain mainly by blocking NMDA receptors, which reduces central sensitization and wind-up in the spinal cord and brain. By dampening these excitatory processes that amplify nociceptive signals after tissue injury or inflammation, it provides analgesia and can lower opioid needs, with particular benefit for neuropathic or refractory pain and as an opioid-sparing adjunct in perioperative care.

Key safety concerns include dissociation and psychotomimetic experiences—patients may feel detached or have vivid dreams or hallucinations, especially during initiation or emergence. It also increases sympathetic activity, which can raise blood pressure and heart rate, so caution is needed in cardiovascular disease or uncontrolled hypertension. There is some risk of delirium or cognitive disturbance, particularly in older adults, and in certain situations there are concerns about effects on intracranial pressure. Finally, there is potential for misuse or dependence with repeated exposure, underscoring the need for careful patient selection and monitoring.