Ketamine: Route of Administration
There are many different ways to put a medication into the body. You can swallow it, inject it, rub it onto the skin, inhale it, insert it as a suppository, etc. This is called the Route of Administration, which we’ll abbreviate here as ROA.
Intravenous (IV) infusion is by far the most common and most studied ketamine ROA for depression. If you tallied all the volunteers from all the ketamine studies to date, probably 98% of them received infusions. On this site and elsewhere you’ll see the terms “IV” and “infusion” used interchangeably.
The ROA makes all the difference in the world. You expect cough syrup to work if you swallow it, but what if you rub it on your skin? You expect a first-aid cream to relieve pain from a cut if you put it on the wound, but what if you snort it? Ketamine for depression is no different: it works best when it is administered with a particular ROA.
Ketamine can be put in the body with several ROAs:
Sprayed into the sinus cavities (intranasal)
Under the tongue (sublingual)
Intramuscular injection with a syringe (IM)
The rate of delivery is also critical. Has your doctor ever given you an antibiotic for an infection? A typical regimen is one dose daily for a week. If you took the entire 7-day prescription in one gulp, do you think it would still work? What if you took one pill weekly, instead of daily? If you do, you’ll render the drug useless, but the only thing you’ve changed is the rate.
You don’t need to schedule your antibiotic to the exact minute, as long as it’s roughly once per day. But some meds require extreme precision for their rates, like anesthesia in the operating room. If it’s administered too quickly it can kill you. Too slowly, and you might wake up while your abdomen is open. An anesthesiologist can recognize signs that the rate is too fast or slow, and fine-tune it accordingly. Ketamine for depression is no different: it works best when it is delivered to the brain at a certain rate.
If ketamine is put into your body with the right ROA, and delivered to your brain at the right rate, it will create unique conditions in the brain. These conditions trigger a delicate cascade of events in the brain that can relieve symptoms.
Why are IV Infusions the most effective ROA? Let’s use baking a cake as a metaphor. The first thing you need to bake a cake is the right ingredients, in the right quantities.
After IV, intranasal is the second-most common ketamine ROA, although it’s still quite rare.
We’re grateful each time a physician is willing to embrace the research and use ketamine. However, we have serious concerns about ketamine being given via IM.