Products
Ketamine is commercially available as a solution for injection (Ketalar, generic). It has been approved in many countries since 1969. Esketamine nasal spray was approved in 2019 (Switzerland: 2020) for the treatment of treatment-resistant depression (see there).
Structure and properties
Ketamine (C13H16ClNO, Mr = 237.7 g/mol) is a cyclohexanone derivative derived from phencyclidine (“angel dust”). It is a ketone and an amine and is present in the injection solution as ketamine hydrochloride, a racemate and white crystalline powder that is readily soluble in water. The pure enantiomer esketamine is also used medicinally.
Effects
Ketamine (ATC N01AX03) causes what is called “dissociative anesthesia.” The patient is unresponsive and in a kind of trance. It is anesthetic and at the same time analgesic and amnestic. It also has dissociative, sedative, local anesthetic, anticonvulsant, bronchodilator, and sympathomimetic properties. Ketamine increases blood pressure and heart rate and induces mild hyperventilation. Unlike other anesthetics, it is hardly respiratory depressant. Furthermore, ketamine is also antidepressant with a rapid onset of action, see under esketamine nasal spray. As with dextromethorphan and phencyclidine, the effects are due to antagonism at -methyl-D-aspartate (NMDA) receptors. In addition, numerous other interactions with other receptor systems have been described.
Indications
Ketamine is used in anesthesia and is used to induce and maintain anesthesia. For treatment of treatment-resistant depression, see esketamine nasal spray.
Dosage
According to the SmPC. The solution for injection may be administered intravenously and intramuscularly.
Abuse
Ketamine is abused as an intoxicant in part because it can cause vivid hallucinations and imaginings. Like dextromethorphan, it causes dissociation (“out-of-body experience”), a subjective separation of body and mind. Even at therapeutic doses, vivid dreams may occur during the waking phase. Ketamine is swallowed, snorted, injected or ingested. Abuse is not advised because severe adverse effects are possible and the drug can lead to dependence.
Contraindications
- Hypersensitivity
- Untreated and inadequately controlled hypertension.
- Patients in whom an increase in blood pressure is a hazard.
- Preeclampsia
- Eclampsia
- Hyperthyroidism not treated or insufficiently treated.
For complete precautions, see the drug label.
Interactions
Drug-drug interactions have been described with anesthetics, sleeping pills, muscle relaxants, aminophylline, thyroid hormones, and halothane, among others.
Adverse effects
The most common possible adverse effects include rapid heartbeat, high blood pressure, and waking reactions. Other adverse reactions include indigestion, increased salivation, airway obstruction, local reactions at the injection site, tonic and clonic movements, and visual disturbances. Rarely, severe hypersensitivity reactions and cardiac arrhythmias may occur. Respiratory depression is possible if injected too rapidly.
