Overview
Ketamine is a rapid-acting general anesthetic and dissociative agent with analgesic properties. It produces a trance-like state while providing pain relief, sedation, and amnesia. It is used for induction and maintenance of anesthesia, procedural sedation, and treatment of depression and chronic pain.
Mechanism of Action
Ketamine is a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist. It blocks glutamate binding to NMDA receptors, leading to dissociative anesthesia, analgesia, and amnesia. It also interacts with opioid receptors, monoaminergic receptors, muscarinic receptors, and voltage-sensitive calcium channels.
Indications
- Induction and maintenance of general anesthesia
- Procedural sedation and analgesia
- Treatment-resistant depression (off-label)
- Chronic pain management (off-label)
- Status epilepticus (off-label)
Dosage
Dosage varies by indication and route. For anesthesia induction: IV 1-2 mg/kg, IM 3-4 mg/kg. For procedural sedation: IV 0.5-1 mg/kg, IM 2-4 mg/kg. For depression: IV 0.5 mg/kg over 40 minutes (off-label). Always titrate to effect.
Contraindications
- Absolute contraindication to ketamine anesthesia
- Known hypersensitivity to ketamine or excipients
- Conditions where increased blood pressure would be hazardous
Side Effects
- Cardiovascular: Hypertension, tachycardia
- Central nervous system: Emergence reactions, hallucinations, dizziness
- Gastrointestinal: Nausea, vomiting
- Respiratory: Respiratory depression, laryngospasm
- Other: Increased salivation, diplopia, nystagmus
Interactions
- Benzodiazepines and opioids: May enhance CNS depression
- Theophylline: May lower seizure threshold
- Sympathomimetics: May increase cardiovascular effects
- Alcohol: May increase CNS depression