Ketamine is well-known to veterinarians. It is hard to imagine a veterinary drug cabinet without it. Developed originally in 1962 as a battlefield anesthetic for wounded soldiers, it was quickly adopted by veterinarians for use in their patients, and unlike many anesthetic agents, whose day comes and goes, ketamine has been part of the basic tool kit for veterinarians for the entire time.
It has also moved beyond it’s original use as a balm for injured soldiers, and is found in all hospitals . Indications for use in humans include (from Wikipedia):
- Pediatric anesthesia (as the sole anesthetic for minor procedures or as an induction agent followed by muscle relaxant and endotracheal intubation)
- Asthmatics or patients with chronic obstructive airway disease
- As part of a cream, gel, or liquid for topical application for nerve pain—the most common mixture is 10% ketoprofen, 5% Lidocaine, and 10% ketamine. Other ingredients found useful by pain specialists and their patients as well as the compounding pharmacists who make the topical mixtures include amitriptyline, cyclobenzaprine, clonidine, tramadol, and mepivicaine and other longer-acting local anaesthetics.
- In emergency medicine in entrapped patients suffering severe trauma
- Emergency surgery in field conditions in war zones
- To supplement spinal / epidural anesthesia / analgesia utilizing low doses
THE KETAMINE EXPERIENCE
Using ketamine in a clinic, a new veterinarian learns quickly that at as a sole agent, ketamine is not very good. The animals tend to become rigid during their sedation, their eyes remain open, and they don’t exhibit the floppy type of sedation that we prefer when working with a sedated or anesthetized animal. Furthermore, recoveries from ketamine look rather bizarre and uncomfortable, with the animal swinging his head back and forth as if he’s watching a marathon game of tennis. Therefore, when used in a veterinary clinic, ketamine is virtually always combined with another drug, generally one that provides relaxation. A historically common ‘cocktail’ is s 50:50 volume mixture of ketamine and valium.
Humans, likewise, report hallucinations when using the drug as a sole agent, and physicians will often combine it with other drugs to minimize this effect. The hallucinogenic potential has made ketamine a popular ‘club’ drug, like MDMA (Ecstasy) or Rohypnol. Until 1999, Ketamine was unscheduled, meaning that it wasn’t a controlled substance. We could use the drug without having to log every single dose used, and without fear of scrutiny from the FDA. Alas, because of ketamine’s growing popularity as a recreational drug, the Feds moved and made ketamine a controlled substance.
I’m not quite sure how this was discovered, but ketamine has a rapid and profound effect on depression. Unlike Prozac and the other selective serotonin reuptake inhibitors (SSRIs) which usually take 3-6 weeks to “kick-in”, ketamine takes effect within 24 hours, and often within 2 or 3 hours of administration.
And here is the strange part. Although ketamine’s half-life is only 3 hours, the anti-depressive effect seems to last at least a week. (A half life is the time it takes for half of the substance to be cleared, so, for example after 4 half-lives [1/2->1/4->1/8->]1/16th of the substance will remain.)
THE FUTURE OF DEPRESSION THERAPY?
So, imagine this. You are in the midst of a depressive episode. Instead of taking a several week regimen of pills, you go to the doctor’s office in the morning, and by lunchtime you are feeling like yourself again.
Fortunately, instead of burying this because of fears of abuse, studies are going forward. The National Institute of Mental Health is conducting clinical trials of the effect of ketamine on major depression and bipolar disorder. The Department of Defense is collaborating with Mt. Sinai School of Medicine on a clinical trial testing ketamine as a rapid treatment for Post-Traumatic Stress Disorder.
There are doctors who are already using ketamine to treat depression. At UCSD, the psych department offers treatment-resistant depressives intravenous ketamine as a treatment. Because it is not an approved use of ketamine, insurance will not cover it. Ketamine is not an expensive drug. Perhaps in the future depressives will be able to dose themselves with intramuscular shots, much the same as diabetics treat themselves with insulin.