Repeated subcutaneous injections of ketamine significantly improved symptoms in a small group of older adults with treatment-resistant depression, researchers found in a pilot study published online in The American Journal of Geriatric Psychiatry.
The randomized controlled trial is the first to assess the efficacy and safety of ketamine in the geriatric patient population.
“These findings take us a big step forward as we begin to fully understand the potential and limitations of ketamine's antidepressant qualities,” said lead author Colleen Loo, MD, a professor in the School of Psychiatry at the University of New South Wales, Sydney, Australia.
“Not only was ketamine well-tolerated by participants, with none experiencing severe or problematic side effects, but giving the treatment by a simple subcutaneous injection (a small injection under the skin) was also shown to be an acceptable method for administering the drug in a safe and effective way.”
Overall, the response and remission rate for older adults receiving ketamine was 68.8%.
Australian researchers tested individualized dosing of ketamine using a dose-titration method in 16 adults age 60 and older. Participants received increasing doses over 5 weeks. The double-blind, placebo-controlled trial included 1 session in which participants received an active treatment substitute that, similar to ketamine, caused sedation.
After the randomized controlled trial, participants received 12 ketamine doses in an open-label phase.
At a 6-month follow-up, 7 of 14 older adults who had completed the randomized controlled trial had depression remission — 5 of whom remitted at doses below the common ketamine dose of 0.5 mg/kg, researchers reported. Repeated treatments, they added, resulted in a higher likelihood of remission or a longer time to relapse.
“Elderly patients with severe depression face additional barriers when seeking treatment for the condition. Many medications may cause more side effects or have lower efficacy as the brain ages,” said researcher Duncan George, MBBS, School of Psychiatry, University of New South Wales. “Older people are also more likely to have comorbidities like neurodegenerative disorders and chronic pain, which can cause further complications due to ketamine's reported side effects.
“Our results indicate a dose-titration method may be particularly useful for older patients, as the best dose was selected for each individual person to maximize ketamine's benefits while minimizing its adverse side effects.”
George D, Gálvez V, Martin D, et al. Pilot randomized controlled trial of titrated subcutaneous ketamine in older patients with treatment-resistant depression. The American Journal of Geriatric Psychiatry. 2017 June 13;[Epub ahead of print].