Better known as an anesthetic or as an illicit hallucinogenic drug, ketamine has also long been noted for alleviating depression.
But ketamine has not been tested in a large clinical trial, and all evidence of its antidepressant effects has come from anecdotes and small studies of fewer than 100 patients.
Now, in the largest study of its kind, researchers at Skaggs School of Pharmacy and Pharmaceutical Sciences at University of California San Diego mined the FDA Adverse Effect Reporting System (FAERS) database for depression symptoms in patients taking ketamine for pain.
They found that depression was reported half as often among the more than 41,000 patients who took ketamine, as compared to patients who took any other drug or drug combination for pain.
The study, published May 3 in Scientific Reports, also uncovered antidepressant effects for three other drugs typically used for other purposes —
- the pain reliever diclofenac and
- the antibiotic minocycline.
“This study extends small-scale clinical evidence that ketamine can be used to alleviate depression, and provides needed solid statistical support for wider clinical applications and possibly larger scale clinical trials.”
The FAERS database contains more than 8 million patient records. The research team focused on patients in the database who received ketamine, narrowing their study population down to approximately 41,000. They applied a mathematical algorithm to look for statistically significant differences in reported depression symptoms for each patient.
The team found that the incidence of depression symptoms in patients who took ketamine in addition to other pain therapeutics dropped by 50 percent (with an error margin less than 2 percent) compared to the patients who took any other drug or drug combination for pain.
Patients who took ketamine also less frequently reported pain and opioid-associated side effects, such as constipation, as compared to patients who received other pain medications
they compared ketamine patients with patients taking other pain medications. That control group eliminated the possibility that people who take ketamine have less depression because they have less pain.
Three other drugs with previously under-appreciated antidepressant effects also emerged from this analysis: Botox, used cosmetically to treat wrinkles and medically to treat migraines and other disorders; diclofenac, a nonsteroidal anti-inflammatory drug (NSAID); and minocycline, an antibiotic
The researchers hypothesize that the antidepressant effects of diclofenac and minocycline may be due, at least in part, to their abilities to reduce inflammation.
According to the World Health Organization, more than 300 million people experience depression worldwide.
If not effectively treated, depression can become a chronic disease that increases a person’s risk of mortality from suicide, heart disease or other factors
For financial and ethical reasons, ketamine has never been tested for its safety and effectiveness in treating depression in a large-scale clinical trial, but it reportedly works much more rapidly than standard antidepressants.
Ketamine is relatively inexpensive and is covered by most health insurance plans if three other antidepressants fail.