Ketamine has been around for about 30 years and was initially used only in veterinary medicine. Over the past 2 decades, it has become known that ketamine is a general anesthetic with hallucinogenic and analgesic (pain relieving properties).
The drug has a unique ability to differentiate perception from sensation. It is currently widely used in pediatric anesthesia. Ketamine is structurally related to PCP, a drug known for its psychedelic effects and vivid hallucinations. The drug has a tendency to produce a feeling of an out-of-body experience.
Pharmacology of Ketamine
Ketamine can cause profound analgesia, respiratory depression, cardiovascular stimulation and amnesia when injected. However, despite the anesthesia, the protective reflexes are maintained. It has excellent analgesic activity and useful for control of severe pain. Ketamine causes an insensate feeling throughout the body. Prolonged use has been associated with physical and psychological addiction. In the majority of inpiduals who frequently use ketamine, tolerance does develop thus requiring the addicts to consume higher doses.
In clinical medicine, ketamine is administered either intravenously or intramuscularly. For illicit uses, ketamine is prepared by evaporating the liquid from the legitimate pharmaceutical product and pulverizing the residue into a powder. All of the ketamine abused has been perted from legal sources. Theft of veterinary/pharmacy clinics is the most frequently reported source of illicit ketamine. Ketamine is commonly snorted by abusers. Intra-muscular injection is also a widely used method for abuse. Injected Ketamine takes a few seconds to work whereas snorted ketamine takes 5-15 minutes to take effect.
Symptoms of Ketamine Use
Ketamine is known to cause hallucinations, nausea, mental clouding, loss of memory and an amnestic feeling may occur. Numerous inpiduals report out of body experiences after having undergone anesthesia with ketamine. Physical features of ketamine use include increased heart rate, paralyzed feeling, numbness, impaired attention, delirium, and high blood pressure.
Is Ketamine Addictive?
Although ketamine does not give rise to physical dependence like that seen with morphine, heroin or alcohol, it is associated with a powerful psychological addiction like that seen with cocaine. Because of its ability to produce intense vivid psychedelic effects it is frequently abused. The psychedelic effects and out of body experiences are primary reasons why the drug is abused.
The dose of ketamine which is used by drug addicts is only about 10-25% of the therapeutic dose required to induce anesthesia. At these low doses, it behaves more like a stimulant than a sedative and does not affect the breathing or heart rate, although exceptions do occur.
At very high doses, ketamine behaves more like other anesthetics and can induce respiratory arrest and increase blood pressure. Deaths with abuse of ketamine alone are rare. The majority of fatalities occur when ketamine is combined with other CNS depressants like alcohol, benzodiazepines and a mixture of other illicit drugs.
Prolonged use of ketamine can result in amnesia, impaired motor function, delirium, and respiratory problems that can be fatal. Ketamine can cause loss of in consciousness, neuroses or other mental clouding. Other common side effects include confusion, delirium, vivid dreams, hallucinations and feelings of detachment from the body. Some physicians routinely use haloperidol or a benzodiazepine to alleviate these distressing symptoms. When injected, ketamine can also cause a significant increase in blood pressure, abnormal heart rhythms, respiratory depression, airway obstruction, visual problems, seizures, skin rash and pain at the injected site.
Respiratory depression may occur with over dosage or too rapid a rate of administration of ketamine, in which case mechanical ventilation should be available. Mechanical support of respiration is preferred to administration of anti-dotes. Prolonged recovery time from respiratory arrest may occur if barbiturates and/or narcotics are used concurrently with ketamine.
Ketamine has a wide margin of safety; several instances of unintentional administration of overdoses of ketamine (up to ten times that usually required) have been followed by prolonged but complete recovery.
Usage in Pregnancy and Elderly
Since the safe use in pregnancy, including obstetrics (either vaginal or abdominal delivery), has not been established, ketamine use is not recommended. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
Ketamine addiction, like all addiction begins with the acceptance of a problem by the inpidual. Several drug rehabilitation and treatment facilities are available for ketamine treatment. There are no antidotes to ketamine and the majority of therapy is based on psychotherapy and behavior modification.
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