Is ketamine an opioid? No, ketamine is not classified as an opioid. It belongs to a different class of medications called dissociative anesthetics. While opioids and ketamine both have pain-relieving effects, they work through different mechanisms. Opioids primarily bind to opioid receptors in the brain and spinal cord, blocking pain signals, whereas ketamine acts on different receptors and produces analgesic effects by affecting the nervous system differently.

What are Opioids?

Opioids are a class of drugs that include prescription pain relievers like morphine, oxycodone, and fentanyl, as well as the illegal drug heroin. Opioids work by binding to opioid receptors in the brain, spinal cord, and other areas of the body. These receptors are part of the body’s endogenous opioid system, which plays a role in controlling pain, reward, and addictive behaviors. When opioids attach to these receptors, they block pain signals from reaching the brain. They also activate the reward system in the brain, causing euphoria, relaxation, and drowsiness. In higher doses, opioids can slow or stop a person’s breathing by acting on the respiratory center in the brainstem. Opioids are highly effective for treating both acute and chronic pain when used properly. However, they also have a high potential for misuse and addiction due to their euphoric effects. With prolonged use, tolerance can develop, leading people to take higher doses to achieve the same effect. Stopping opioids after dependence has set in will lead to withdrawal symptoms like muscle aches, anxiety, sweating, and diarrhea.

Ketamine Drug Classification

Ketamine is classified as a dissociative anesthetic, not an opioid. This classification is based on ketamine’s unique mechanism of action and effects on the central nervous system which differ markedly from opioids. Unlike opioids, which act on opioid receptors, ketamine works as an N-methyl-D-aspartate (NMDA) receptor antagonist. It blocks NMDA receptors which modulate excitatory neurotransmission in the brain and spinal cord. This leads to a dissociative state characterized by pain relief, amnesia, and immobility. Ketamine was first synthesized in 1962 and gained popularity in anesthesiology for its ability to induce dissociation and analgesia without compromising respiratory function. This dissociative anesthetic effect gave rise to ketamine’s classification separate from opioid analgesics. While opioids and ketamine may share some similar clinical effects, like pain relief and euphoria, their pharmacological classes and mechanisms of action are distinct. The World Health Organization’s pain ladder does not include ketamine or other dissociative anesthetics in the same class as opioid medications. Overall, the unique properties of ketamine warrant its classification outside of the opioid drug class.

Ketamine’s Mechanism of Action vs Opioids

Ketamine is unique among substances with abuse potential in that it is an NMDA receptor antagonist. NMDA receptors are proteins on nerve cells that bind to glutamate, which is the brain’s major excitatory neurotransmitter. When glutamate binds to NMDA receptors, it opens channels that allow calcium and sodium ions to enter the cell, causing nerve excitation and signaling. Ketamine blocks NMDA receptors by binding to the receptors inside the ion channels. This prevents glutamate from binding and activating the receptor. By blocking NMDA receptors, ketamine inhibits nerve signaling in certain pathways of the brain. The resulting state is known as “dissociation”—senses a and perceptions are disconnected from one another. At lower doses, ketamine is thought to preferentially inhibit NMDA receptors on gamma-aminobutyric acid (GABA)-releasing interneurons. This disinhibits pyramidal neurons, increasing excitatory transmission mediated by another neurotransmitter called AMPA. The ultimate effects are reflected in changes in mood, cognition, and sensory and motor processing. At higher doses, ketamine directly inhibits NMDA receptors on pyramidal neurons, limiting their activity. This leads to the profound detachment from reality and anesthesia associated with ketamine intoxication. The uniqueness of ketamine’s mechanism differentiates it from other substances and underlies some of its special properties.

According to Get Smart About Drugs; Ketamine produces hallucinations. It distorts perceptions of sight and sound and makes the user feel disconnected and not in control. A “Special K” trip is touted as better than that of LSD or PCP because its hallucinatory effects are relatively short, lasting approximately 30 to 60 minutes as opposed to several hours.

Opioid Mechanisms

Opioids produce their effects by binding to opioid receptors in the brain, spinal cord, and other areas of the body. There are three main types of opioid receptors – mu, delta, and kappa. The mu opioid receptor is responsible for mediating analgesia, euphoria, respiratory depression, and physical dependence associated with opioids. Morphine and similar opioid analgesics exert their effects primarily through the mu receptor. When opioids bind to the mu receptor, they block pain signals from reaching the brain and also trigger the release of dopamine in the brain’s reward system, contributing to euphoric effects. Activation of the mu receptor also slows breathing by inhibiting brainstem regions that control respiration. This effect becomes more pronounced at higher doses and makes overdose life-threatening. The delta opioid receptors play a role in analgesia as well as emotional processes. The kappa receptors are involved in pain relief, sedation, and dissociation. While mu agonists are the most clinically relevant, some opioids may have mixed activity at the different receptor types. Overall, binding to opioid receptors triggers downstream effects of pain relief, euphoria, sedation, slower breathing, nausea, and constipation. Repeated opioid use causes adaptions in the opioid receptor system that lead to tolerance and dependence. Understanding the mechanisms behind opioid binding and signaling provides insight into their addictive properties and dangers.

Effects of Ketamine vs Opioid

Ketamine Effects

Ketamine is known for inducing potent dissociative and psychedelic effects. At lower doses, ketamine can cause feelings of detachment, numbness, and loss of coordination. Many describe feeling like they are floating outside their body. Higher doses lead to more intense dissociation, often with hallucinations, visual distortions, and altered perceptions of time and space. Users may experience vivid dream-like states, visions, or a sense of entering alternative realities. The dissociative qualities have led to ketamine being classified as a “dissociative anesthetic.” In addition to the psychedelic, hallucinogenic properties, ketamine can also cause confusion, memory loss, inability to move, and loss of consciousness at high doses. The dissociative mental state has been described by some as an “out-of-body experience.” While ketamine may have pain relieving qualities, many are drawn to its ability to alter consciousness and induce trance-like states. Frequent or high-dose use carries risks like flashbacks, ongoing dissociation, and other long-term psychological problems. Responsible use requires care and moderation.

Opioid Effects

Opioid drugs produce effects such as pain relief, drowsiness, mental confusion, nausea, constipation, and slowed breathing. They work by binding to opioid receptors in the brain, spinal cord, and other areas of the body. This blocks pain signals sent from the brain to the body and releases large amounts of dopamine throughout the body, creating a euphoric high. Some of the major effects of opioids include:

  • Analgesia – Reduces or eliminates pain. This is the primary therapeutic effect of opioids and makes them effective pain relievers.
  • Euphoria – Produces an intense feeling of pleasure and contentment. This effect underlies the high and abuse potential of opioids.
  • Drowsiness and mental confusion – Causes drowsiness, cognitive impairment, and lack of concentration. This effect increases with higher doses.
  • Respiratory depression – Slows breathing rate, which can lead to lack of oxygen and death at high doses. This is the most serious side effect of opioids.
  • Nausea and vomiting – Common side effects that can discourage opioid use and abuse. Tolerance develops to these effects over time.
  • Constipation – Long-term opioid use often leads to severe constipation that can be difficult to treat. This is due to opioids binding to receptors in the stomach and digestive system.
  • Physical dependence – Repeated use causes adaptation in the brain, leading to tolerance and withdrawal symptoms if opioids are stopped suddenly. This causes users to compulsively seek out the drug.
  • Sedation – Strong tranquilizing effect that induces sleepiness and stupor. This effect is utilized for sedation in medical settings but can cause lack of functioning when abused.

Overall, opioids carry a high risk of abuse and overdose due to their ability to produce euphoria and relieve both physical and psychological pain. With repeated use, tolerance develops rapidly, requiring higher doses to achieve the same effects.

This quickly leads to dependence and addiction.

Risk of  Ketamine Abuse vs Opioid Abuse

Ketamine Abuse

While ketamine is sometimes classified as a dissociative anesthetic and thought of as separate from opioids, it is still also considered by some health organizations like the FDA as a controlled substance with potential for abuse and dependence. Some of the signs of ketamine abuse or addiction may include:

  • Taking higher doses than prescribed or more frequently
  • Experiencing strong cravings for the drug
  • Continuing use despite harmful effects
  • Developing a tolerance over time requiring more to get the same effect

There are some key differences in the potential risks and patterns of abuse between ketamine and traditional opioids like morphine or heroin:

  • Ketamine does not act on opioid receptors in the brain directly like traditional opioids. It has a different mechanism of action targeting NMDA receptors. This means it does not produce the same addictive biochemical processes and withdrawal.
  • Ketamine may have lower potential for deadly overdose compared to opioids. However, it still carries risks at high recreational doses including impaired breathing, heart problems, convulsions, and death.
  • Ketamine abuse may lead more to psychological vs. physiological dependence. Tolerance can still develop with frequent use. Withdrawal tends to involve primarily psychological cravings rather than severe physical symptoms.
  • Patterns of compulsive use and addiction seen with ketamine abuse are different than traditional opioids. Ketamine abusers tend to use episodically in binges rather than daily maintenance of intoxication.
  • Ketamine destroys the bladder wall.

Overall, while ketamine abuse should still be taken seriously, it presents some different risks and patterns compared to traditional opioid narcotics. However, it still carries dangers and any non-medical use should be avoided. More research is needed on the long-term impact and treatment of ketamine addiction.

Ketamine’s Unique Properties; Is Ketamine an Opioid?

While ketamine and opioids share some similarities, ketamine has several unique properties that differentiate it from traditional opioids. Most notably, ketamine does not bind to opioid receptors in the body like typical opioid drugs. Instead, ketamine acts primarily on glutamate receptors known as NMDA receptors. Binding to NMDA receptors produces feelings of dissociation and sensory distortions that opioids do not cause. Ketamine also has a different safety and dependence profile compared to opioids. Studies have found that ketamine has a lower potential for abuse and addiction. The dissociative effects of ketamine make long-term abuse challenging, whereas opioids often have a high risk of dependence. Additionally, ketamine does not cause respiratory depression, a dangerous side effect of many opioids that can lead to overdose. The biggest risk with ketamine tends to be psychological rather than life-threatening physical effects. Ketamine also has shown promising results as a fast-acting antidepressant in low doses. Opioids are not used as antidepressants and do not have the same potential mental health benefits. While ketamine and opioids may share some similar properties, ketamine has a distinct mechanism of action, side effect profile, and therapeutic potential. Considering ketamine an opioid does not capture its unique attributes as a dissociative anesthetic agent.

Conclusion

Ketamine is not classified as an opioid but rather as a dissociative anesthetic. While it does produce analgesic effects, its mechanism of action is completely different than that of opioids. Opioids like morphine, heroin, oxycodone and others bind to opioid receptors in the brain, while ketamine acts as an NMDA receptor antagonist. The effects of ketamine are also distinct from opioids. While both can produce feelings of euphoria and analgesia, opioids cause sedation and respiratory depression while ketamine produces dissociation, hallucinations and an “out of body” experience. Ketamine does not carry the same high risk of lethal overdose as opioids. However, it can still be addictive and abused, particularly in the form of long-term use. While not an opioid, ketamine still requires caution and responsible use. In summary, although ketamine has some effects that may outwardly seem similar, it has completely different properties and mechanisms from opioids. It does not meet the criteria to be classified as an opioid. Moving forward, ketamine’s potential as an antidepressant and anesthetic should continue to be researched responsibly.