The occupancy-driven pharmacology model in psychopharmacology has guided drug discovery and development for decades, whereby the goal is stable receptor occupancy over an extended period with a direct relationship of drug exposure to pharmacodynamic and therapeutic response. Event-driven pharmacology (EDP) is a concept where the acute pharmacodynamic actions of a plastogen, a transient binding...
(R,S)-ketamine (ketamine) induces rapid and sustained antidepressant-relevant neuroplastogenic effects in vivo. The metabolite (2R,6R)-hydroxynorketamine (2R6R) forms shortly after the administration of ketamine, and independently elicits rapid plasticity and sustained metaplasticity. Ketamine's therapeutic actions appear to result from distinct, time-sensitive plasticity phases, though the...
Recent antidepressant drug development focuses on a next generation of drugs to rapidly relieve symptoms. Yet, how ketamine, the prototype rapid-acting antidepressant, maintains symptom relief days after drug elimination, and how repeated doses sustain longer-lasting therapeutic effects, remains unclear. Derived from elements of metaplasticity (synaptic priming), this review discusses a...
ABSTRACT Background: Opioid use disorder (OUD) is a chronic relapsing condition with a high mortality rate. While medications such as methadone are valuable first-line therapies, retention is poor, with the highest dropout rates early in a treatment attempt. Poor outcomes are due in part to the very high rates of co-morbid depression in people with OUD, as depression can drive opioid use....
Cell ReportsMay 21, 2025Lace M Riggs, Sage Aronson, Ta-Chung M. Mou et al.2 citations
An acute increase in excitatory synaptic transmission contributes to the rapid antidepressant actions of neuroplastogens, including ketamine and its bioactive metabolite, (2R,6R)-hydroxynorketamine (HNK). It is hypothesized that drug-induced metaplastic changes in synaptic strength account for therapeutically relevant behavioral adaptations in vivo. Using the plasticity-deficient Wistar Kyoto...
The pharmacologically active (R,S)-ketamine (ketamine) metabolite (2 R,6 R)-hydroxynorketamine (HNK) maintains ketamine's preclinical antidepressant profile without adverse effects. While hypotheses have been proposed to explain how ketamine and its metabolites initiate their antidepressant-relevant effects, it remains unclear how sustained therapeutic actions arise following drug elimination....
Subanesthetic doses of (R,S)-ketamine (ketamine) have demonstrated rapid and robust antidepressant effects in individuals with depression. However, individual variability in response to ketamine exists, and current biomarkers of ketamine treatment response are not entirely understood. Preclinical evidence suggests a link between hypothalamic-pituitary-adrenal (HPA) axis activation, a...
A large and disproportionate portion of the burden associated with major depressive disorder (MDD) is due to treatment-resistant depression (TRD). Intravenous (R,S)-ketamine (ketamine) and intranasal (S)-ketamine (esketamine) are rapid-acting antidepressants that can effectively treat TRD. However, there is variability in response to ketamine/esketamine, and a personalized approach to their use...
(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...
(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...
The authors sought to assess the prosocial, entactogen effects of ketamine. Pleasure from social situations was assessed in a sample of participants with treatment-resistant depression from randomized, double-blind, placebo-controlled studies, using four items of the Snaith-Hamilton Pleasure Scale (SHAPS) at five time points over 1 week following treatment with ketamine (0.5 mg/kg...
The discovery that subanesthetic doses of (R, S)-ketamine (ketamine) and (S)-ketamine (esketamine) rapidly induce antidepressant effects and promote sustained actions following drug clearance in depressed patients who are treatment-resistant to other therapies has resulted in a paradigm shift in the conceptualization of how rapidly and effectively depression can be treated. Consequently, the...
Ketamine is an effective antidepressant, but there is substantial variability in patient response and the precise mechanism of action is unclear. Neuroimaging can provide predictive and mechanistic insights, but findings are limited by small sample sizes. This systematic review covers neuroimaging studies investigating baseline (pre-treatment) and longitudinal (post-treatment) biomarkers of...
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...
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...
(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),...
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 [(...
For decades, symptoms of depression have been treated primarily with medications that directly target the monoaminergic brain systems, which typically take weeks to exert measurable effects and months to exert remission of symptoms. Low, subanesthetic doses of ( R,S)-ketamine (ketamine) result in the rapid improvement of core depressive symptoms, including mood, anhedonia, and suicidal...
(R,S)-Ketamine produces rapid, robust, and sustained antidepressant effects in major depressive disorder. Specifically, its pharmacological efficacy in treatment refractory depression is considered a major breakthrough in the field. However, the mechanism of action of ketamine's rapid effect remains to be determined. In order to identify pathways that are responsible for ketamine's effect, a...
Traditional pharmacological treatments for depression have a delayed therapeutic onset, ranging from several weeks to months, and there is a high percentage of individuals who never respond to treatment. In contrast, ketamine produces rapid-onset antidepressant, anti-suicidal, and anti-anhedonic actions following a single administration to patients with depression. Proposed mechanisms of the...
Abstract New antidepressant pharmacotherapies that provide rapid relief of depressive symptoms are needed. The NMDA receptor antagonist ketamine exerts rapid antidepressant actions in depressed patients but also side effects that complicate its clinical utility. Ketamine promotes excitatory synaptic strength, likely by producing high - frequency correlated activity in mood-relevant regions of...