How Ketamine May Help with Chronic Pain

November 11, 2022

Summary: Although ketamine has been around for some time, its roles have been changing. It started its journey as a potent anesthetic drug and then gained popularity as a party drug. Now, doctors are increasingly using it to manage chronic intractable pains. A kind of pain that would not respond well to other treatment methods. Studies suggest that it works by affecting NMDA receptors, opioid receptors, monoamine oxidases, dopamine, serotonin, and many other receptors. Moreover, ketamine provides prolonged relief in difficult-to-treat conditions.

There are many ways to treat pain; among them, non-steroidal anti-inflammatory drugs are the drugs of choice for most acute or chronic pain. However, they work well for mild to moderate pains. They are also suitable for inflammatory pain. But chronic pain is complex, and it occurs due to many reasons. Even worse, in some, chronic pain becomes intractable pain. Experience shows that most commonly used drugs provide limited relief in chronic pain. Thus, doctors often have to use opioids, which have been around for a millennium. However, opioids have a poor safety profile.

Therefore, doctors are exploring the role of other drugs. Ketamine has been getting particular attention for pain management. It is a drug that has been around for almost half a century. It started its journey as an anesthetic, then made to clubs as a recreational drug, and now it is increasingly used to manage chronic pain.

Of course, doctors would not use ketamine for some acute pain. However, they are more likely to use it in chronic pain caused due to multiple reasons. Thus, it is pretty good for intractable pain, too. What is impressive is that the benefits of ketamine outlast its blood concentration, hence the difficulty in understanding how it works.

How does ketamine work for pain?

Though ketamine has been in use for over half a century, its mechanism of action is not fully understood yet. Nevertheless, one thing is known well: it acts on NMDA receptors, thus causing the so-called dissociative state. This altered state of mind also results in significantly reduced pain sensation.

However, its action on NMDA receptors fails to explain its mechanism of action wholly. If this were the prime way it reduces pain sensation, then pain would return once there is insufficient drug concentration in the blood and the person is alert. However, this does not happen; in many instances, pain seems to evaporate almost magically, and it may not return for long.

Therefore, now doctors understand that there is much happening. Ketamine also affects many other receptors like cholinergic, opioids system, sigma receptors, nicotinic, muscarinic, and even monoamine (including dopamine and serotonin). Thus, the drug is able to cause sedation, help with depression, and even alter brain wiring for a long time. In addition, it appears to help reset certain brain centers.

Of course, do not expect ketamine to provide permanent relief. Nonetheless, unlike other medications, ketamine therapy results in sometimes dramatic and long-lasting benefits. Moreover, this effect of ketamine is now supported by many studies. Thus, a meta-analysis in 2019 concluded that it appears to provide significant analgesic benefits in those with refractory pain.

Although ketamine is still not recognized as a mainline pain killer, for reasons understood. It is not a pill that one can take whenever suffering from pain. It causes a dissociative or mind-altering effect and is a controlled substance. And thus, its use is only possible under strict medical supervision.

However, in recent years, many professional associations have come to a consensus regarding using ketamine for pain relief. Consequently, the American Society of Regional Anesthesia and Pain Medicine, the American Academy of Pain Medicine, and the American Society of Anesthesiologists all approve of using ketamine for chronic pain treatment.

Ketamine is not your Regular Painkiller

As already mentioned, it is not a pill you can take whenever and as needed. Instead, it is a drug used strictly under medical supervision. Doctors would usually give low-dose ketamine infusions over a period of forty-five minutes. It rarely affects the working of the heart or breathing, making it quite a safe drug for use in clinics.

Since doctors use it in small amounts, it would not cause severe mind-altering effects, though most would report some unpleasant feelings. However, some may also experience nightmares and hallucinations after its use. Therefore, it is not a medication for everyday use.

Generally, ketamine infusion is good when other medications fail, like complex regional pain syndrome (CRPS), chronic overlapping pain, fibromyalgia, and even spinal cord injury. In addition, some with refractory headaches may also benefit from ketamine therapy.

By Gurpreet Singh Padda, MD, MBA