Ketamine metabolite pilot study in a suicidal depression trial.

Ketamine shows promise as a rapidly-acting treatment for depression and suicidal ideation, but side effects and abuse potential limit its use. Understanding its mechanism of action could help develop analogous but safer drugs. This post hoc study explored relationships of ketamine and metabolites, including hydroxynorketamine enantiomers, (2S,6S)- and (2R,6R)-HNK, to clinical response in a subgroup from a published trial in suicidal depression. Depressed adults with clinically significant suicidal ideation were randomized to double-blind infusion of sub-anesthetic ketamine or midazolam. Ketamine and metabolites were measured after infusion (N = 53). Plasma (2R,6R)-HNK was associated with change (higher levels correlated with less clinical improvement) from baseline to 24 h post-infusion of depression (HDRS-24: Spearman r = 0.37, p = 0.009) and suicidal thoughts (SSI: Spearman r = 0.29, p = 0.041). There were similar correlations with weekly follow-up clinical rating scores for both HNK enantiomers and dehydronorketamine (DHNK). Ketamine and norketamine were not associated with change in depression or suicidal ideation (unadjusted p > 0.28).

Attempted suicide and oxytocin-related gene polymorphisms.

BACKGROUND: Oxytocin may moderate prosocial behaviors, but has also been implicated in negative mental health outcomes. A single-nucleotide polymorphism (SNP) of the oxytocin receptor gene (OXTR), rs53576, and a SNP of the CD38 gene, which regulates oxytocin secretion, rs3796863, have been associated with depression and suicidal ideation. METHODS: We conducted an exploratory study investigating the relationship of these two SNPs to history of suicide attempt. Secondary analyses explored relationships of genotype with sex, diagnosis, history of abuse, depression, suicidal ideation, and attachment and personality traits. Subjects were depressed adults with DSM-IV major depressive disorder (MDD; n = 161) or bipolar disorder (BD; n = 75). RESULTS: The A allele of rs53576 was associated with suicide attempt history. A differential effect of rs3796863 genotype on suicide attempt risk was found by diagnosis. In the BD sample, CC and AC genotypes were associated with higher odds of suicide attempt compared to AA, while in the MDD sample, AC subjects were more likely than CC subjects to have made an attempt. LIMITATIONS: Our assessment of social sensitivity was limited to measures of attachment style and abuse history and did not differentiate between types of abuse. Plasma oxytocin was not measured. CONCLUSIONS: These findings add to evidence for the involvement of oxytocin in suicide attempts and identify a potential biomarker for differentiating depressed attempters from non-attempters.

Effects of anxiety on suicidal ideation: exploratory analysis of a paroxetine versus bupropion randomized trial.

It is unclear whether anxiety increases or decreases suicidal risk. This may contribute to the lack of guidance on which antidepressant medications are best for suicidal depressed patients who present with high anxiety. This study explored whether anxiety predicts suicidal ideation in depressed individuals treated with paroxetine or bupropion. An 8-week double-blind trial comparing controlled-release paroxetine (N=36) versus extended-release bupropion (N=38) for effect on suicidal ideation and behavior in depressed patients with suicidal ideation, past attempt, or both found an advantage for paroxetine, but anxiety effects were not investigated. This secondary analysis explored the relationship, measured at baseline and weekly, of anxiety with suicidal ideation. Anxiety severity measured weekly correlated with suicidal ideation severity irrespective of treatment (P=0.012). Patients with high baseline anxiety showed a trend toward faster reduction of suicidal ideation with paroxetine compared with bupropion treatment (standard P=0.047; bootstrap P=0.077). The latter finding, if confirmed in larger samples, could enhance choice of antidepressant medication for suicidal, depressed patients presenting with high levels of anxiety.

Ketamine for Rapid Reduction of Suicidal Thoughts in Major Depression: A Midazolam-Controlled Randomized Clinical Trial.

OBJECTIVE: Pharmacotherapy to rapidly relieve suicidal ideation in depression may reduce suicide risk. Rapid reduction in suicidal thoughts after ketamine treatment has mostly been studied in patients with low levels of suicidal ideation. The authors tested the acute effect of adjunctive subanesthetic intravenous ketamine on clinically significant suicidal ideation in patients with major depressive disorder. METHOD: In a randomized clinical trial, adults (N=80) with current major depressive disorder and a score ≥4 on the Scale for Suicidal Ideation (SSI), of whom 54% (N=43) were taking antidepressant medication, were randomly assigned to receive ketamine or midazolam infusion. The primary outcome measure was SSI score 24 hours after infusion (at day 1). RESULTS: The reduction in SSI score at day 1 was 4.96 points greater for the ketamine group compared with the midazolam group (95% CI=2.33, 7.59; Cohen's d=0.75). The proportion of responders (defined as having a reduction ≥50% in SSI score) at day 1 was 55% for the ketamine group and 30% for the midazolam group (odds ratio=2.85, 95% CI=1.14, 7.15; number needed to treat=4.0). Improvement in the Profile of Mood States depression subscale was greater at day 1 for the ketamine group compared with the midazolam group (estimate=7.65, 95% CI=1.36, 13.94), and this effect mediated 33.6% of ketamine's effect on SSI score. Side effects were short-lived, and clinical improvement was maintained for up to 6 weeks with additional optimized standard pharmacotherapy in an uncontrolled follow-up. CONCLUSIONS: Adjunctive ketamine demonstrated a greater reduction in clinically significant suicidal ideation in depressed patients within 24 hours compared with midazolam, partially independently of antidepressant effect.