Ketamine is a medication mainly used for starting and maintaining anesthesia. It induces a trance-like state while providing pain relief, sedation, and memory loss. Other uses include sedation in intensive care and treatment of pain and depression. Heart function, breathing, and airway reflexes generally remain functional. Effects typically begin within five minutes when given by injection, and last up to approximately 25 minutes.
Common side effects include agitation, confusion, or hallucinations as the medication wears off. Elevated blood pressure and muscle tremors are relatively common. Spasms of the larynx may rarely occur. Ketamine is an NMDA receptor antagonist, but it may also have other actions.
Ketamine was discovered in 1962, first tested in humans in 1964, and approved for use in the United States in 1970. It was extensively used for surgical anesthesia in the Vietnam War due to its safety. It is on the World Health Organization’s List of Essential Medicines, the safest and most effective medicines needed in a health system. It is available as a generic medication. The wholesale price in the developing world is between US$0.84 and US$3.22 per vial. Ketamine is also used as a recreational drug for its hallucinogenic and dissociative effects.
The use of ketamine is cautioned against in cases of:
- Conditions worsened by an increase in blood pressure or heart rates, such as angina, stroke, and poorly controlled high blood pressure. Ketamine increases both heart rate and blood pressure.
- Psychiatric disorders: Ketamine can cause hallucinations, and therefore may exacerbate the symptoms of certain psychiatric disorders.
- Ketamine was once thought to cause increased intracranial pressure (IICP): as of 2014, this is believed not to be the case.
- Raised intraocular pressure (IOP): Ketamine can further increase IOP.
- Penetrating eye injury: This can increase the risk of loss of eye contents, due to increased IOP.
- Acute porphyria: Ketamine is considered porphyrinogenic, that is, it may provoke an attack of acute porphyria, a disease of the nervous system, in susceptible people.
Ketamine is employed to alleviate moderate to severe pain.
Analgesics like Datril or paracetamol are accustomed to treat delicate or moderate pain. It also can be used to reduce the temperature of fevers.