bioRxiv (Cold Spring Harbor Laboratory)
June 8, 2025
Anna Onisiforou, Morfeas Koumas, Andria Michael et al.
preprint
Abstract Background Opioid abstinence induces persistent emotional disturbances and widespread neuroplastic changes, in areas of the brain including the hippocampus. Although ketamine and its metabolite ( 2R,6R )-hydroxynorketamine (HNK) show potential in reversing opioid abstinence-related deficits in rodents, the molecular mechanisms underlying their efficacy remain poorly understood. Methods...
Biological Psychiatry
March 15, 2025
Anna Onisiforou, Andria Michael, Markos Apostolakis et al.
14 citations
Opioid use disorder (OUD) has reached epidemic proportions, with many countries facing high levels of opioid use and related fatalities. Although currently prescribed medications for OUD are considered lifesaving, they inadequately address negative affect and cognitive impairment, resulting in high relapse rates to nonmedical opioid use even years after drug cessation (protracted abstinence)....
Clinical pharmacology and therapeutics
November 1, 2024
Shruti M Raja, Jeffrey T Guptill, Michelle Mack et al.
34 citations
(R,S)-Ketamine (ketamine) is a dissociative anesthetic that also possesses analgesic and antidepressant activity. Undesirable dissociative side effects and misuse potential limit expanded use of ketamine in several mental health disorders despite promising clinical activity and intensifying medical need. (2R,6R)-Hydroxynorketamine (RR-HNK) is a metabolite of ketamine that lacks anesthetic and...
Neuropharmacology
November 1, 2024
Thi Mai Loan Nguyen, Jean-Philippe Guilloux, Céline Defaix et al.
3 citations
(R,S)-ketamine (ketamine) has rapid and sustained antidepressant (AD) efficacy at sub-anesthetic doses in depressed patients. A metabolite of ketamine, including (2R,6R)-hydroxynorketamine ((6)-HNKs) has been reported to exert antidepressant actions in rodent model of anxiety/depression. To further understand the specific role of ketamine's metabolism in the AD actions of the drug, we evaluated...
Journal of Neuroscience
January 3, 2023
Panos Zanos, Kyle A Brown, Polymnia Georgiou et al.
109 citations
Ketamine is a well-characterized NMDA receptor (NMDAR) antagonist, although the relevance of this pharmacology to its rapid (within hours of administration) antidepressant actions, which depend on mechanisms convergent with strengthening of excitatory synapses, is unclear. Activation of synaptic NMDARs is necessary for the induction of canonical long-term potentiation (LTP) leading to a...
Translational Psychiatry
May 2, 2022
Ruin Moaddel, Panos Zanos, Cristan A Farmer et al.
32 citations
Abstract Subanesthetic-dose racemic ( R,S )-ketamine (ketamine) produces rapid, robust, and sustained antidepressant effects in major depressive disorder (MDD) and bipolar disorder (BD) and has also been shown to effectively treat neuropathic pain, complex regional pain syndrome, and post-traumatic stress disorder (PTSD). However, to date, its mechanism of action remains unclear. Preclinical...
British Journal of Pharmacology
July 1, 2019
Panos Zanos, Jaclyn N. Highland, Xin Liu et al.
(R)-Ketamine (arketamine) may have utility as a rapidly acting antidepressant. While (R)-ketamine has lower potency than (R,S)-ketamine to inhibit NMDA receptors in vitro, the extent to which (R)-ketamine shares the NMDA receptor-mediated adverse effects of (R,S)-ketamine in vivo has not been fully characterised. Furthermore, (R)-ketamine is metabolised to (2R,6R)-hydroxynorketamine (HNK),...
Proceedings of the National Academy of Sciences
March 13, 2019
Panos Zanos, Jaclyn N. Highland, Brent W. Stewart et al.
153 citations
Significance Despite available medications for depression, currently approved antidepressants take months to exert therapeutic effects, and ∼30% of patients remain treatment resistant. In contrast, a single subanesthetic dose of ketamine exerts rapid (within hours) and sustained antidepressant actions. Preclinical studies indicate that the ketamine metabolite ( 2R , 6R )-hydroxynorketamine [(...
Proceedings of the National Academy of Sciences of the United States of America
February 22, 2019
E. Lumsden, Timothy A. Troppoli, S. J. Myers et al.
159 citations
Significance Standard antidepressant treatments require weeks to show effectiveness. A single subanesthetic dose of ketamine rapidly attenuates many clinical signs and symptoms of depression; however, ketamine treatment also has many adverse effects, including dissociation and potential for abuse, which are mediated by NMDA glutamate receptor (NMDAR) inhibition. Previous work has revealed that...
Pharmacological Reviews
June 26, 2018
Panos Zanos, Ruin Moaddel, Patrick J. Morris et al.
1,272 citations
Ketamine, a racemic mixture consisting of (S)- and (R)-ketamine, has been in clinical use since 1970. Although best characterized for its dissociative anesthetic properties, ketamine also exerts analgesic, anti-inflammatory, and antidepressant actions. We provide a comprehensive review of these therapeutic uses, emphasizing drug dose, route of administration, and the time course of these...
Molecular Psychiatry
March 13, 2018
Panos Zanos, T. Gould
1,112 citations
Clinical studies have demonstrated that a single sub-anesthetic dose of the dissociative anesthetic ketamine induces rapid and sustained antidepressant actions. Although this finding has been met with enthusiasm, ketamine’s widespread use is limited by its abuse potential and dissociative properties. Recent preclinical research has focused on unraveling the molecular mechanisms underlying the...
Nature
April 24, 2016
Panos Zanos, Ruin Moaddel, Patrick J. Morris et al.
1,602 citations
Major depressive disorder affects around 16 per cent of the world population at some point in their lives. Despite the availability of numerous monoaminergic-based antidepressants, most patients require several weeks, if not months, to respond to these treatments, and many patients never attain sustained remission of their symptoms. The non-competitive, glutamatergic NMDAR (N-methyl-d-aspartate...