Ketamine for Chronic Pain Management: Current Role and Future Directions

Healthcare providers and patients alike have been intrigued by the potential benefits of ketamine in improving patients’ lives.

with Charles F. von Gunten, MD, PhD

When you hear the word “ketamine” your mind may instantly go to one of its many monikers as a commonly used street drug: “special K,” “vitamin K,” or “Super K.” This drug, however, has been used in medicine for more than 50 years, most commonly for its role as an anesthetic during surgery. Recently, however, there has been much interest in the role of ketamine as a treatment for chronic pain management, and doctors have begun to prescribe low doses of this medication to patients with chronic pain conditions such as complex regional pain syndrome (CRPS).

Ketamine is a drug with sedative (sleep-producing), analgesic (pain-relieving), and amnesic (short-term memory loss) effects. It combats pain by acting against a specific chemical receptor known as N-methyl-D-aspartate, or NMDA, which is found in the nervous system and, in part, modulates pain. However, ketamine interacts with other receptors as well, broadening its clinical uses.

However, illicit use of the medication comes with risks, and the DEA has been following its distribution closely.

There has been much interest in the role of ketamine as a treatment for chronic pain management. (Source: 123RF)

When Should Doctors Use Ketamine?

Generally, two types of patients with chronic pain may benefit from this medication: patients with chronic pain that have not had much success with other pain medications or treatments, and/or patients with chronic pain who plan to undergo surgery.

“I think of ketamine as a very effective pain medicine for a small number of patients: In general, patients who have been taking opioids for pain and found them to be ineffective,” Charles F. von Gunten, MD, PhD, vice president of medical affairs for Palliative and Hospice Medicine at Ohio Health in Columbus, OH, told PPM.

Several conditions, including cancer, CRPS, fibromyalgia, neuropathic pain, phantom pain, postherpetic neuralgia, sickle cell disease, and spinal injury, may result in chronic pain. Ketamine has been used to manage pain in all of these conditions. However, clinical studies have shown varying outcomes. Multiple professional organizations, including the American Society of Regional Anesthesia and Pain Medicine (ASRA), the American Academy of Pain Medicine (AAPM), and the American Society of Anesthesiologists (ASA), have agreed that the collective evidence has shown weak to moderate support for ketamine’s role in managing pain for these conditions.

As Dr. von Gunten notes, “Its use in pain medicine is because of a very specific action in the spinal cord on a very specific set of receptors. Not all patients in pain have these receptors activated.”

Due to this, doctors who prescribe ketamine do so with care, especially in patients with poorly controlled cardiovascular disease, severe liver disease, poorly controlled psychosis, substance abuse problems, elevated intracranial pressure, and glaucoma.

“The pain patient should come with a spirit of inquiry. It is considered by no means a panacea; it does not work for all pain, and it needs to be carefully dosed and the patients carefully chosen by a specialist. Even in that case, there are some patients that it works brilliantly in and in others it does not have any effect at all,” Dr. von Gunten explained.

How is Ketamine Administered?

Ketamine can be administered through many different routes. Most commonly, ketamine is delivered through an intravenous (IV) pump. Sometimes, patients will ingest ketamine orally as a pill. Ketamine can also be applied directly to the skin as a topical gel or cream, inhaled through the nose, or injected into a muscle or bone. These available routes of administration make ketamine highly adaptable to several clinical scenarios. Regardless of the route chosen, the medication must be dosed adequately and cautiously to be effective and safe.

Other Uses of Ketamine

Ketamine has multiple “off-label” uses as well (that is, those that are not formally approved by the FDA). Doctors may prescribe ketamine to patients with seizures who are not responding well to other medications. Post-traumatic stress disorder (PTSD) and severe depression may benefit from ketamine treatment as well; studies are underway.

Experts speculate that the growing number of off-label uses for ketamine may be due to the length of time it has been available to healthcare providers. However, the number of prescriptions being ordered is outpacing the development of medical consensus guidelines for proper distribution and best practices. Overall, experts agree that further research is needed to explore the role of ketamine in other conditions before they can be properly put into motion as a definitive treatment option.

What Does the Future Hold?

Dr. von Gunten weighed in by saying, “The thing that is most promising about ketamine is it points out the importance of this particular receptor that is involved in some pain situations. The direction of research is to focus on this receptor and find better drugs that will only affect the receptor without having the adverse effects that ketamine is widely known for. We are using this for now, all the while hoping that research will deliver a more effective and safer drug, and we’ll better understand how this receptor fits into the broad framework of how we treat different kinds of pain.”

This article is not meant to provide clinical advice. Ask your doctor about whether ketamine may be helpful in managing your specific chronic pain condition or symptoms.

Updated on: 12/04/18
Continue Reading:
Complex Regional Pain Syndrome: When the Nurse Becomes the Patient