The N-methyl-D-aspartate receptor antagonist ketamine has rapid onset activity in treatment-resistant depression, post-traumatic stress disorder and obsessive compulsive disorder. Due to similarities in brain network activity in depression and anxiety disorders, we hypothesized that ketamine might also be active in other refractory anxiety disorders. We evaluated the efficacy and safety of ketamine in 12 patients with refractory generalized anxiety disorder and/or social anxiety disorder who were not currently depressed, using an ascending single dose study design (0.25, 0.5, 1 mg/kg administered subcutaneously) at weekly intervals. Within 1 h of dosing, patients reported reduced anxiety, which persisted for up to seven days. A dose-response profile was noted for anxiolytic effects, dissociative side effects, and changes in blood pressure and heart rate, with minor changes at 0.25 mg/kg, and progressively greater and more durable changes at the higher doses. Ten of 12 patients were treatment responders at 0.5-1 mg/kg. Ketamine was safe and well tolerated in this population. Ketamine may be a potential therapeutic alternative for patients with refractory generalized anxiety disorder/social anxiety disorder. Along with its demonstrated effectiveness in patients with treatment-resistant depression, obsessive compulsive disorder and post-traumatic stress disorder, these data raise the intriguing possibility that ketamine may have broad efficacy in disorders characterized by negative emotional states, and that these disorders may share a common precipitating neurobiology.

Ibogaine is a psychoactive substance that may reduce opioid withdrawal symptoms. This was the first clinical trial of noribogaine, ibogaine's active metabolite, in patients established on methadone opioid substitution therapy (OST). In this randomized, double-blind, placebo-controlled single ascending-dose study, we evaluated the safety, tolerability, and pharmacokinetics of noribogaine in 27 patients seeking to discontinue methadone OST who had been switched to morphine during the previous week. Noribogaine doses were 60, 120, or 180 mg (n = 6/dose level) or matching placebo (n = 3/dose level). Noribogaine was well tolerated. The most frequent treatment-emergent adverse events were noneuphoric changes in light perception ∼1 hour postdose, headache, and nausea. Noribogaine had dose-linear increases for AUC and C and was slowly eliminated (mean t range, 24-30 hours). There was a concentration-dependent increase in QTcI (0.17 ms/ng/mL), with the largest observed mean effect of ∼16, 28, and 42 milliseconds in the 60-, 120-, and 180-mg groups, respectively. Noribogaine showed a nonstatistically significant trend toward decreased total score in opioid withdrawal ratings, most notably at the 120-mg dose; however, the study design may have confounded evaluations of time to resumption of OST. Future exposure-controlled multiple-dose noribogaine studies are planned that will address these safety and design issues.

The aim of this study was to switch patients established on methadone opioid substitution therapy (OST) to morphine over 1 week. Subjects established on daily methadone OST (mean dose 60 mg/day) were switched to morphine slow-release capsules, dosed at 4× the previous total daily methadone dose, for 6 days, then given morphine syrup dosed q3h. All 27 subjects enrolled in this study completed the switch from methadone to morphine. Opioid withdrawal symptoms (OWS) peaked within 12-24 hours of starting morphine, and 24/27 subjects required higher daily morphine doses (mean 5.2× multiple). Pharmacokinetic evaluation showed that 91% of methadone was cleared during this time, with a mean elimination half-life of 59 hours. The most frequent treatment-emergent non-OWS adverse events were headache, nausea, constipation, and neck pain. The method described here appears to be a safe and acceptable approach to switch subjects from methadone to morphine.