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Pharmacology · Drugs and Prescriptions

Ketamine hydrochloride

Ketamini hydrochloridum

A medication from the group of CNS-acting agents, representing short-acting non-inhalational anesthetics. It induces a unique state of dissociative anesthesia, achieving powerful analgesia without complete depression of consciousness and vital functions.

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MechanismNMDA receptor blockade (eliminates the effect of glutamate)
HemodynamicsStimulates the cardiovascular system: increases blood pressure, heart rate, and cardiac output
DurationShort-acting (up to 15 minutes when administered IV)
Formulation5% solution in ampoules (2, 5, 10 ml) and vials (20 ml)
How to write a prescription
Rp.: Sol. Ketamini hydrochloridi 5% - 2 ml
D.t.d. N 10 in amp.
S. Внутривенно струйно из расчета 2-3 мг/кг массы тела для вводного наркоза

Alternative prescription entries: Sol. Ketamini hydrochloridi 5% - 10 ml; Sol. Ketamini 5% - 2 ml; Sol. Ketamini hydrochloridi 5% - 20 ml

Dosage form
Solution in ampoules 5% in 2, 5, and 10 ml; solution in vials 5% - 20 ml
Administration
Intramuscularly 0.004–0.008 g/kg; intravenously 0.002–0.003 g/kg as a rapid bolus
Group
Agents affecting the central nervous system
3 min readFor medical studentsUpdated 09/24/2026
Material prepared by WhiteCoat Pro editorial team based on platform study guidesReviewed by medical editor: Aulov A. A., general practitioner · 09/24/2026

Mechanism of action and the concept of dissociative anesthesia

By chemical structure, ketamine is an arylcyclohexylamine, a phencyclidine derivative. Its target in the brain is NMDA receptors. The drug acts as a non-competitive antagonist, eliminating the excitatory effect of glutamate on CNS structures.

Ketamine induces dissociative anesthesia. This is a state of functional disconnection: some brain structures are depressed while others remain active. Unlike other non-inhalational anesthetics (propofol, etomidate, sodium thiopental), ketamine produces pronounced analgesia. Consciousness is only partially lost, accompanied by a mild hypnotic effect and amnesia. The classical stage of surgical anesthesia is not achieved.

Effect on vital functions and hemodynamics

Ketamine is the drug of choice in emergency situations due to its safety profile regarding vital functions:

  • Respiration and reflexes: Spontaneous breathing is fully preserved (no apnea occurs with slow administration). Muscle tone does not drop, and protective reflexes (laryngeal, pharyngeal, cough) remain active.
  • Cardiovascular system: This is the only non-inhalational anesthetic that stimulates the cardiovascular system. It causes tachycardia (increased heart rate), increased cardiac output, and elevated blood pressure (hypertension).

The mechanism of this cardiostimulation lies in the activation of sympathetic innervation and the blockade of norepinephrine reuptake. The peak hemodynamic effect is observed at 2–4 minutes, with a decrease occurring after 10–20 minutes.

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Pharmacokinetics and indications for use

The drug is highly lipophilic, ensuring its rapid penetration across the blood-brain barrier (BBB).

Indications:

  • Induction of anesthesia.
  • General anesthesia.
  • Standalone analgesia for short, painful procedures (e.g., management of burn surfaces).

Onset and duration:

  • Intravenous administration: effect appears instantly ("at the tip of the needle" within 30–60 seconds), duration of anesthesia is 5–10 minutes.
  • Intramuscular administration: effect develops within 2–6 minutes, duration is 15–30 minutes.

Side effects and their management

The main drawback of ketamine limiting its widespread routine use is its specific effect on the CNS during emergence from anesthesia. Patients frequently develop delirium:

  • Psychomotor agitation.
  • Vivid, often nightmare-like dreams.
  • Visual hallucinations.

The high risk of postoperative psychoses requires pharmacological prevention. Tranquilizers (diazepam) are traditionally used to manage these side effects.

Formulation and dosage

According to the prescription reference, Ketamini hydrochloridum is available as a 5% solution:

  • In 2, 5, and 10 ml ampoules.
  • In 20 ml vials.

Dosing regimen:

  • Intravenously: 0.002–0.003 g/kg (administered as a rapid IV push).
  • Intramuscularly: 0.004–0.008 g/kg.
How to memorize

Ketamine is "C" and "D": Cardiostimulation and Dissociative anesthesia. The patient Breathes, Blood pressure is Maintained, but they have Bad dreams.

Class and exam questions

Why is ketamine called a dissociative anesthetic?

It causes functional disconnection in the CNS: depresses certain brain structures while preserving the activity of others. The patient is partially conscious, breathes independently, reflexes are preserved, but pain is not felt.

How does ketamine affect blood pressure?

Unlike most anesthetics, it increases blood pressure and causes tachycardia due to sympathoadrenal system stimulation and norepinephrine reuptake blockade.

What is used to treat hallucinations after ketamine anesthesia?

Diazepam is used for the prevention and management of psychomotor agitation, visual hallucinations, and nightmares (delirium).

Does ketamine depress respiration?

No, with slow administration, spontaneous breathing is preserved and apnea does not occur. Airway protective reflexes are also maintained.

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What else to study on this topic

  • Comparative profile of intravenous anesthetics: ketamine, propofol, sodium thiopental
  • The role of NMDA receptors and glutamate in CNS function
  • Coadjuvants: use of antidepressants and anticonvulsants for pain management
  • Premedication drugs: selection of tranquilizers to prevent side effects
  • Mechanisms of action of barbiturates (GABA-A receptor complex) compared to ketamine

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