Ketamine

Ketamine is a dissociative anesthetic widely used in medicine and veterinary medicine for anesthesia, pain management, and sedation. It is also known for its psychedelic effects and has gained attention for its potential as an antidepressant. Despite its medical applications, ketamine is also used recreationally for its hallucinogenic properties, leading to concerns about abuse and addiction.

Ketamine chemical structure

S-Ketamine 3D molecular structure

Medical Uses

Ketamine is used in various medical settings, including hospitals, emergency rooms, and veterinary clinics. Some of its primary applications include:

Anesthesia

Ketamine is used as an anesthetic for surgeries and medical procedures, particularly in situations where maintaining airway reflexes is critical. Unlike other anesthetics, ketamine does not significantly suppress respiration, making it valuable in emergency settings.

Pain Management

Ketamine is administered for chronic pain conditions, such as:

• Neuropathic pain
• Cancer pain
• Complex regional pain syndrome (CRPS)
• Post-surgical pain management

Low-dose ketamine infusions have been increasingly used as an adjunct to traditional opioid therapies, helping to reduce opioid dependence.

Treatment-Resistant Depression

Recent studies suggest that ketamine has rapid and significant antidepressant effects, especially in individuals with treatment-resistant depression. A single dose can provide relief from depressive symptoms within hours, with effects lasting up to a week.

Ketamine is also being researched for its potential to treat:

• Post-traumatic stress disorder (PTSD)
• Obsessive-compulsive disorder (OCD)
• Suicidal ideation
• Anxiety disorders

Emergency Medicine

Ketamine is used in emergency settings due to its rapid onset and safety profile. It is useful for:

• Trauma patients – Provides anesthesia and sedation without causing significant drops in blood pressure.
• Severe asthma attacks – Functions as a bronchodilator to improve breathing.
• Agitation and sedation – Used in psychiatric emergencies for acute agitation or violent behavior.

Pediatric and Veterinary Use

Ketamine is commonly used in pediatric anesthesia because of its safety in maintaining respiration and circulation.

In veterinary medicine, ketamine is widely used for sedation and anesthesia in cats, dogs, horses, and other animals.

Mechanism of Action

Ketamine primarily acts as an NMDA receptor antagonist in the central nervous system (CNS). By blocking these receptors, it inhibits excessive excitatory neurotransmission, leading to its anesthetic and analgesic effects.

Additionally, ketamine affects:

• Opioid receptors – contributing to its pain-relief properties.
• Dopamine system – leading to potential antidepressant effects.
• Sigma receptors – involved in dissociative and hallucinogenic experiences.

Pharmacokinetics

Route of Administration	Bioavailability	Onset of Action	Duration of Effects
Intravenous (IV)	100%	30 sec – 1 min	10 – 15 min
Intramuscular (IM)	93%	2 – 4 min	30 – 60 min
Intranasal	45 – 50%	5 – 10 min	60 min
Sublingual	24 – 30%	15 – 30 min	1 – 2 hours
Oral	16 – 20%	30 – 40 min	2 – 6+ hours

Side Effects

While ketamine is a valuable medical drug, it also carries risks, particularly when misused.

Short-Term Side Effects

Common side effects include:

• Dizziness
• Nausea and vomiting
• Increased blood pressure and heart rate
• Blurred vision
• Confusion and disorientation
• Hallucinations and dissociation (often described as a "K-hole")
• Difficulty speaking and moving

Long-Term Side Effects

Prolonged or heavy ketamine use can lead to:

• Cognitive impairment – Memory loss, trouble concentrating.
• Ketamine bladder syndrome – Severe inflammation, pain, and potential bladder dysfunction.
• Liver and kidney damage – Due to chronic exposure.
• Psychological dependence – Leading to addiction and withdrawal symptoms.

Recreational Use

Ketamine is widely used as a club drug due to its hallucinogenic and dissociative effects. Users often seek a sensation of detachment from reality, which can range from mild to profound.

Common Forms of Recreational Use:

• Snorted (Insufflation) – Most common, with effects lasting 30 – 60 minutes.
• Injected (IM or IV) – Produces stronger effects with a rapid onset.
• Oral Consumption – Effects last longer but are less intense.

The "K-Hole" Experience: At high doses, users report entering a "K-hole", described as:

• Out-of-body sensations
• Ego dissolution
• Time distortion
• Vivid hallucinations

Long-term recreational use is associated with serious bladder damage, memory impairment, and psychological dependence.

Legal Status

Ketamine is classified differently across countries:

Country	Legal Status
United States	Schedule III (Controlled, but used medically)
United Kingdom	Class B (Illegal without prescription)
Canada	Schedule I (Highly restricted)
Australia	Schedule 8 (Controlled substance)
Germany	Anlage III (Requires special prescription)

Research and Future Applications

Antidepressant Research Ongoing research is exploring ketamine’s rapid antidepressant effects, particularly for:

• Treatment-resistant depression
• Bipolar depression
• Postpartum depression
• Suicidal ideation

Treatment for Addiction Studies suggest ketamine may help treat:

• Alcohol use disorder
• Opioid addiction
• Nicotine dependence

Summary

Ketamine is a powerful anesthetic, analgesic, and psychedelic drug with widespread medical uses. While its potential for treating depression and chronic pain is promising, its recreational abuse raises concerns over addiction and long-term health effects. The drug remains a valuable tool in medicine but requires careful administration and regulation.

See Also

• Dissociative anesthetics
• NMDA receptor antagonists
• Psychedelic therapy
• General anesthesia
• Pain management

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