Ketamine

Ketamine acts on the central nervous system as a potent NMDA‑receptor antagonist, providing dissociative anesthesia and analgesia across several clinical settings.

• Induction of anesthesia: produces rapid loss of consciousness for surgical procedures.
• Analgesia: offers effective pain relief during and after operative or diagnostic interventions.
• Sedation: facilitates procedural sedation for diagnostic or therapeutic examinations.
• Treatment‑resistant depression (off‑label): may provide rapid antidepressant effects in selected patients.

• Ketamine blocks the N‑methyl‑D‑aspartate (NMDA) receptor channel, reducing excitatory neurotransmission in the brain. This antagonism leads to dissociative anesthesia, analgesia, and modulation of synaptic plasticity, which underlies its rapid antidepressant effects when used off‑label. The drug also interacts with opioid receptors and monoaminergic pathways, contributing to its analgesic and psychotropic properties.

Ketamine may cause a range of adverse reactions that vary in frequency and severity.

Common Side Effects

• Hypertension: transient elevation of blood pressure.
• Tachycardia: increased heart rate during and shortly after administration.
• Nausea or vomiting: gastrointestinal upset.
• Emergence phenomena: vivid dreams, hallucinations, or confusion during recovery.

Serious or Rare Side Effects

• Respiratory depression: reduced breathing effort requiring support.
• Laryngospasm: sudden closure of the vocal cords.
• Cardiac arrhythmias: irregular heart rhythms.
• Severe agitation or delirium: intense psychomotor disturbances.
• Allergic reactions: rash, itching, or anaphylaxis.

Ketamine should be used with careful clinical assessment and monitoring.

• Cardiovascular monitoring: observe blood pressure and heart rate throughout administration.
• Respiratory support: be prepared to manage airway and ventilation if needed.
• Psychiatric evaluation: assess for history of psychosis before off‑label use.
• Drug interactions: review concomitant medications that affect CNS or cardiovascular function.
• Storage: Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Ketamine can interact with several drug classes, requiring attention to avoid adverse outcomes.

Major Interactions (Avoid)

• Central nervous system depressants: may potentiate respiratory depression.
• Sympathomimetic agents: can exacerbate hypertension and tachycardia.
• Monoamine oxidase inhibitors (MAOIs): increase risk of hypertensive crisis.

Moderate Interactions (Monitor Closely)

• Benzodiazepines: may reduce emergence phenomena but alter anesthetic depth.
• Opioids: additive analgesic effect may require dose adjustment.
• Anticholinergic drugs: can modify heart rate response.