Ketamine
CLASS
- phencyclidine derivative hypnotic and analgesic
MECHANISM OF ACTION
- NMDA receptor antagonist resulting in dissociative anaesthesia (profound analgesia with superficial sleep)
- interacts with opioid receptors – mu, delta and kappa
- muscarinic receptors – partial antagonist effect (bronchodilation, sympathomimetic, delirium)
- Na+ channel – mild LA like properties
PHARMACEUTICS
- colourless solution, 10/50/100mg/mL, racemic, benzethonium chloride (preservative)
DOSE
- IV, IM or PO, extradural, intrethcal, rectal or nasal
- IM – 10mg/kg (6min onset)
- IV – 2mg/kg (30 sec onset) or rate of 50mcg/kg/min
- analgesic dose: 0.1-0.3mg/kg -> 0.1mg/kg/hr
INDICATIONS
- induction of anaesthesia and emergency intubation
- asthma
- hypotension/ haemodynamic instability (e.g. trauma, sepsis)
- severe metabolic acidosis (allowing spontaneous ventilation)
- delayed sequence intubation to allow preoxygenation with spontaneous ventilation
- procedural sedation (especially for children, prehospital, and in mass casualties)
- analgesia – perioperative and chronic pain
- severe unresponsive asthma (bronchodilator)
- refractory status epilepticus
- controversial role in the treatment of depression
ADVERSE EFFECTS
- salivation
- increased ICP (although newer data questions this)
- PONV
- emergence delirium -> hallucinations
PHARMACOKINETICS
- Absorption – bioavailability = 20%
- Distribution – t1/2 alpha = 10 min, 50% protein bound, Vd 1.8L/kg
- Metabolism – hepatic, some active metabolites
- Elimination – t1/2 beta = 2.5 hrs, urinary
OTHER INFORMATION
- Ketamine can be used for refractory status epilepticus (observational studies suggest ketamine is an effective option for refractory status epilepticus due to antagonism of excitotoxic NMDA receptors) (Hofler and Trinka, 2018)
References and Links
CCC Pharmacology Series
Respiratory: Bosentan, Delivery of B2 Agonists in Intubated Patients, Nitric Oxide, Oxygen, Prostacyclin, Sildenafil
Cardiovascular: Adenosine, Adrenaline (Epinephrine), Amiodarone, Classification of Vasoactive drugs, Clevidipine, Digoxin, Dobutamine, Dopamine, Levosimendan, Levosimendan vs Dobutamine, Milrinone, Noradrenaline, Phenylephrine, Sodium Nitroprusside (SNiP), Sotalol, Vasopressin
Neurological: Dexmedetomidine, Ketamine, Levetiracetam, Lignocaine, Lithium, Midazolam, Physostigmine, Propofol, Sodium Valproate, Sugammadex, Thiopentone
Endocrine: Desmopressin, Glucagon Therapy, Medications and Thyroid Function
Gastrointestinal: Octreotide, Omeprazole, Ranitidine, Sucralfate, Terlipressin
Genitourinary: Furosemide, Mannitol, Spironolactone
Haematological: Activated Protein C, Alteplase, Aprotinin, Aspirin, Clopidogrel, Dipyridamole, DOACs, Factor VIIa, Heparin, LMW Heparin, Protamine, Prothrombinex, Tenecteplase, Tirofiban, Tranexamic Acid (TXA), Warfarin
Antimicrobial: Antimicrobial Dosing and Kill Characteristics, Benzylpenicillin, Ceftriaxone, Ciprofloxacin, Co-trimoxazole / Bactrim, Fluconazole, Gentamicin, Imipenem, Linezolid, Meropenem, Piperacillin-Tazobactam, Rifampicin, Vancomycin
Analgesic: Alfentanil, Celecoxib, COX II Inhibitors, Ketamine, Lignocaine, Morphine, NSAIDs, Opioids, Paracetamol (Acetaminophen), Paracetamol in Critical Illness, Tramadol
Miscellaneous: Activated Charcoal, Adverse Drug Reactions, Alkali Therapies, Drug Absorption in Critical Illness, Drug Infusion Doses, Epidural Complications, Epidural vs Opioids in Rib Fractures, Magnesium, Methylene Blue, Pharmacology and Critical Illness, PK and Obesity, PK and ECMO, Sodium Bicarbonate Use, Statins in Critical Illness, Therapeutic Drug Monitoring, Weights in Pharmacology
Toxicology: Digibind, Flumazenil, Glucagon Therapy, Intralipid, N-Acetylcysteine, Naloxone, Propofol Infusion Syndrome
- Höfler J, Trinka E. Intravenous ketamine in status epilepticus. Epilepsia. 2018;59 Suppl 2:198-206. [pubmed]
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the Clinician Educator Incubator programme, and a CICM First Part Examiner.
He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.
His one great achievement is being the father of three amazing children.
On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.
| INTENSIVE | RAGE | Resuscitology | SMACC
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Hi!
Thank you for this great summary regarding Ketamine!
I’m trying to find out through which mechanism Ketamine causes hypersalivation. Would you mind helping me please?
Thank you!
Betul Korkmaz