Conway McLean, DPM, Journal columnist

Chronic pain is a tremendous problem in our society, partially due to our increasing longevity. Many Americans are living longer but with damaged joints and old injuries, hampered in their activities as a result. Although never intended for chronic, enduring pain, too many are surviving their day only through the repeated use of anti-inflammatories or over-the-counter analgesics, both of which have potential side effects and complications with prolonged use.

Although the research is ongoing, our choices for lasting pain are inadequate. Non-steroidal drugs, the ubiquitous ibuprofen and its varied iterations, were never meant for long term use. Unlike the dishonest marketing at the root of the opioid epidemic, the opioid drugs can have various negative consequences from long term use, some examples including respiratory depression and addiction. An older drug making a resurgence is ketamine, which has been in regular use in emergency medicine and as part of the drug regimen for operations for many decades.

Ketamine has been used for years for opioid-resistant, long term, intractable chronic pain, but only in particular, specific situations. There has been recent interest in its application for more common conditions, especially because of our limited options for chronic pain. But ketamine’s reputation is tarnished, known by many as a horse tranquilizer and as a street drug, just for recreational purposes. More recently, ketamine has found increasing use in the treatment of depression, another condition for which we have few good choices.

Ketamine was developed in the 1960s as an anesthetic agent and was introduced commercially in 1970, specifically for sedation and anesthesia for surgical procedures. In this arena, its use is well established. It has even been placed on the World Health Organization’s Model List of Essential Medicines. The drug turns out to have some distinctive properties making it notable and unique. When used as anesthesia for surgery, ketamine does not cause relaxation of the blood vessels unlike other agents. A consequence is the maintenance of blood pressure, of great benefit in many operations. Also relevant, it doesn’t depress breathing, again in contrast to many anesthetic agents.

There are certainly applications where the role of ketamine is old, well-established and remains unchallenged. This is the case in the emergency department, particularly for patients with low blood pressure since, again, ketamine does not have the effect of lowering BP. There is strong evidence that it reduces postoperative pain scores, and this results in lessened opioid requirements. Another area of success is with pediatric patients undergoing surgical procedures. Burn victims have traditionally received ketamine prior to dressing changes, an excruciating process for these individuals. Ketamine has been used for years in the battlefield where its properties have made it the agent of choice. Every doctor joining the army is given training in its use.

Some of the controversy of late centers on the treatment of depression with ketamine. Again, the lack of safe, effective therapies colors this discussion. Ketamine has been used for over 20 years for this purpose, but little agreement has been reached on the subject of dosage and regimen, how often and when to take. Many of the studies have looked at an intranasal form of the drug, intended for depression, certainly a convenient method.

The adverse effects of ketamine include hallucinations, agitation, anxiety, and euphoria, as well as dizziness, nausea, sedation, and tachycardia. But the less desirable effects of the drug are dose-dependent: at low dose, it acts on certain receptors, providing an analgesic effect, while at higher doses, the individual is more likely to experience the adverse effects.

Various pharmaceutical companies have been racing to be the first to develop a reliable and convenient form of the drug that effectively treats depression, a market for which there are tremendous profits to be made because of the millions who have failed to respond to existing therapies. The IV form has obvious limitations, including a short duration of action. Unexplained as yet are the lasting improvement in the symptoms of depression from a short-acting medication given at such small doses.

It took years, and mounting evidence, before ketamine gained traction in the psychiatric community as an effective antidepressant. Since the results of the preliminary studies were so convincing, many physicians have been adopting ketamine into their clinical practice, a trend occurring over the last decade or so. Even the Veterans Administration has approved it’s use for their patients who were determined to have treatment-resistant depression (although only after appropriate evaluations).

Because of its unique chemical properties, ketamine has found a wide range of clinical applications. Millions of adults in third world countries have safely received ketamine over the last several decades during surgical and medical procedures, as well as for pain. The drug is very inexpensive, making it especially popular in areas where funds are limited.

There is sufficient evidence to draw conclusions regarding this older, generic drug. Ketamine remains an inexpensive and simple alternative to the inhalational anesthetics for surgical procedures, while its applications for chronic pain and depression are promising but not well established. We need to learn more about its characteristics and actions for these conditions, both tremendous problems plaguing too many of us. Ketamine, or some derivative, may yet turn out to be a widely accepted option for these two widespread conditions, the obstacles to wellbeing that are chronic pain and depression.

EDITORS NOTE: Dr. Conway McLean is a podiatric physician now practicing foot and ankle medicine in the Upper Peninsula, having assumed the practice of Dr. Ken Tabor. McLean has lectured internationally on surgery and wound care, and is board certified in both, with a sub-specialty in foot orthotic therapy. Dr. McLean welcomes questions, comments and suggestions at drcmclean@penmed.com.