By Erik MacLaren, PhD
Intranasal ketamine produces favourable results in the treatment of patients with cancer-related pain, according to a small, ongoing, prospective study presented here at the 35th Annual Meeting of the American Academy of Pain Medicine (AAPM).
More than half of patients with cancer experience pain, and opioid analgesics are limited by undesirable side effects at higher doses.
“Knowing that intravenous ketamine has analgaesic effects, I wanted to come up with a way to give it easily and frequently for this already fragile patient population,” explained Vinita Singh, MD, Emory University School of Medicine, Atlanta, Georgia.
For the study, the researchers continue to assess pain scores and side effects in 12 patients who have cancer, a numerical pain rating scale (NPRS) score of ≥6, and were taking ≥50 mg morphine equivalents daily prior to the start of the study.
Each patient in the study is required to attend 4 sessions and receive 4 escalating doses of ketamine (10 mg nasal, 10 mg intravenous, 30 mg nasal, and 50 mg nasal). Patients are monitored for 4 hours after treatment.
A total of 7 patients have completed the study. All 3 doses of intranasal ketamine, as well as 10 mg intravenous ketamine, have produced significant reductions in NPRS pain scores.
Intranasal administration of ketamine produces a rapid onset of effects — within 1 hour of administration.
The researchers analysed time to maximal pain relief, duration of maximal pain relief, and duration of any pain relief, but there were no significant differences in these measures among any of the ketamine treatments.
The team assessed side effects during each session using the Edmonton Symptom Assessment Scale (ESAS) and the Side Effects Rating Scale for Dissociative Anesthetics (SERSDA). The investigators found that 10 mg intravenous ketamine was the most poorly tolerated treatment. Typical side effects included dizziness, nausea, and a feeling of unreality, although all side effects resolved by the end of each session. Ketamine treatment improved symptoms of fatigue and discomfort.
Although more data are needed to determine the long-term safety of this novel therapy, the researchers are encouraged in the pursuit of intranasal ketamine as a possible new treatment modality for patients with cancer-related pain.