Ketamine

Ketamine is a dissociative anesthetic used for induction and maintenance of anesthesia, procedural sedation, and rapid-acting analgesia in acute trauma and severe pain. Low-dose ketamine infusions or intranasal esketamine are used for treatment-resistant depression and to reduce suicidal ideation. It’s also used in emergency settings for bronchodilation in severe asthma and as an adjuvant for chronic or neuropathic pain when other therapies fail.

Ketamine rapidly alleviates depression by blocking NMDA glutamate receptors, causing a glutamate surge that activates AMPA receptors and downstream signaling (BDNF, mTOR), which restores synaptic connections and plasticity. It can work within hours, especially for treatment-resistant depression. Administration is supervised (IV or intranasal esketamine) because effects are transient and can include dissociation, blood-pressure rise, and misuse risk.

Ketamine can cause short‑term effects such as dizziness, drowsiness, nausea or vomiting, blurred vision, increased heart rate and blood pressure, disorientation, hallucinations or vivid dreams, and respiratory depression in high doses. With repeated use it may produce urinary tract problems (pain, frequency), cognitive impairment, mood changes and risk of dependence. Allergic reactions are possible; monitoring is recommended during and after administration.

Ketamine can rapidly reduce severe or treatment‑resistant anxiety symptoms for some people when given in controlled medical settings, but evidence is still evolving. Short‑term benefits are documented, yet risks include dissociation, elevated blood pressure, sedation and potential for misuse. Long‑term safety and optimal dosing remain unclear. It’s not a first‑line therapy and should be provided and monitored by experienced clinicians.

Ketamine’s acute effects start within minutes and typically last 30–120 minutes (shorter with IV/IM, longer at higher doses). Its elimination half‑life is about 2–3 hours. It may be detectable in blood up to ~24 hours, in urine generally 2–4 days (sometimes longer), and in hair for several months. Individual factors (dose, route, metabolism, frequency) alter these times.

Ketamine can be used for pain management. As an NMDA-receptor antagonist, it reduces central sensitization and can treat acute, perioperative, and some chronic or neuropathic pain, often as an opioid-sparing option. It’s delivered IV, IM, intranasal, or oral in controlled settings. Benefits must be balanced against risks — dissociation, hallucinations, blood pressure/heart-rate increases, and misuse potential — so use requires specialist supervision and individualized dosing.