Some Other Anesthetics May Interfere with Ketamine's Rapid Antidepressant Effect
Newswise — Philadelphia, Pa. (July 26, 2012) - The anesthetic agent ketamine has a fast-acting antidepressant effect, but that doesn't improve the response to electroconvulsive therapy (ECT) for severe depression, according to a study in the September issue of The Journal of ECT, official journal of the International Society for ECT and Neurostimulation. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.
The study did not show the "robust rapid antidepressant response" to ketamine reported in previous studies—perhaps because ketamine was used in combination with a different type of anesthetic. The research was performed by Dr. Gerard Sancora and colleagues of Yale University School of Medicine.
Ketamine Has Rapid Antidepressant Effect…Recent studies have suggested that ketamine brings rapid improvement in patients with severe depression. In contrast to standard antidepressants, which can take weeks to months to have an effect, a single injection of ketamine improves symptoms within a few hours. Electroconvulsive therapy is a highly effective treatment for severe depression, but repeated treatments are generally needed to bring improvement. Ketamine might help to bridge the gap before ECT takes effect. "Interestingly, ketamine has been used in ECT anesthesia for decades," the researchers note. The study included 18 patients with episodes of major depression who were scheduled for ECT after not responding to standard antidepressant drugs. All patients received a drug called thiopental to provide anesthesia for ECT. One group received a low dose of ketamine in addition to thiopental. The ketamine dose was "subanesthetic"—lower than needed to produce anesthesia.
…But Doesn't Enhance Response to ECT for Major DepressionThe study was stopped early when preliminary results showed no improvement in the response to ECT with ketamine. Depression scores improved in both groups; it generally took six ECT treatments over two weeks to show an effect.
Ketamine did not produce the fast antidepressant effect seen in previous studies. In fact, the response to ECT was somewhat faster in patients who received thiopental alone, without ketamine.
Some studies have suggested that ketamine improves the seizure response to ECT while minimizing side effects. In the new study, there was some evidence of a longer seizure response with ketamine.
Why didn't ketamine's rapid antidepressant appear in the new study? There are several possible explanations, but the authors believe the most likely is some type of interaction between ketamine and thiopental, which is a barbiturate anesthetic. "It is conceivable that the thiopental effects interfere with ketamine's mechanism of antidepressant action," Dr. Sancora and colleagues write.
The results don't close the door on the possibility that ketamine could help to improve the response to ECT in patients with severe episodes of major depression. Future studies should consider the effects of different doses, timing, and routes of ketamine administration, or of using ketamine as the sole anesthetic or combined with other types of anesthetics.
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About The Journal of ECT The Journal of ECT covers all aspects of contemporary electroconvulsive therapy, reporting on major clinical and research developments worldwide. Leading clinicians and researchers examine the effects of induced seizures on behavior and on organ systems; review important research results on the mode of induction, occurrence, and propagation of seizures; and explore the difficult sociological, ethical, and legal issues concerning the use of ECT.
About Lippincott Williams & Wilkins Lippincott Williams & Wilkins (LWW) is a leading international publisher of trusted content delivered in innovative ways to practitioners, professionals and students to learn new skills, stay current on their practice, and make important decisions to improve patient care and clinical outcomes. LWW is part of Wolters Kluwer Health, a leading global provider of information, business intelligence and point-of-care solutions for the healthcare industry. Wolters Kluwer Health is part of Wolters Kluwer, a market-leading global information services company with 2011 annual revenues of €3.4 billion ($4.7 billion).
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