Efficacy and safety of a T-type calcium channel blocker in patients with neuropathic pain: A proof-of-concept, randomized, double-blind and controlled trial.

BACKGROUND: T-type calcium channels have been shown to play an important role in the initiation and maintenance of neuropathic pain and represent a promising therapeutic target for new analgesic treatments. Ethosuximide (ETX), an anticonvulsant and a T-type channel blocker has shown analgesic effect in several chronic pain models but has not yet been evaluated in patients with neuropathic pain. METHODS: This proof-of-concept, multicentre, double-blind, controlled and randomized trial compared the efficacy and safety of ETX (given as add-on therapy) to an inactive control (IC) in 114 patients with non-diabetic peripheral neuropathic pain. After a 7-day run-in period, eligible patients aged over 18 years were randomly assigned (1:1) to ETX or IC for 6 weeks. The primary outcome was the difference between groups in the pain intensity (% of change from the baseline to end of treatment) assessed in the intention-to-treat population. This study is registered with EudraCT (2013-004801-26) and ClinicalTrials.gov (NCT02100046). RESULTS: The study was stopped during the interim analysis due to the high number of adverse events in the active treatment group. ETX failed to reduce total pain and showed a poor tolerance in comparison to IC. In the per-protocol analysis, ETX significantly reduced pain intensity by 15.6% (95% CI -25.8; -5.4) from baseline compared to IC (-7.8%, 95% CI -14.3; -1.3; p = 0.033), but this result must be interpreted with caution because of a small subgroup of patients. CONCLUSION: Ethosuximide did not reduce the severity of neuropathic pain and induces, at the doses used, many adverse events. SIGNIFICANCE: This article shows that ETX is not effective to treat neuropathic pain. Nevertheless, per-protocol analysis suggests a possible analgesic effect of ETX. Thus, our work adds significant knowledge to preclinical and clinical data on the benefits of T-type calcium channel inhibition for the treatment of neuropathic pain.

[Misuse and dependence on prescription opioids: Prevention, identification and treatment]. / Mésusage et dépendance aux opioïdes de prescription : prévention, repérage et prise en charge.

Since the 1990s, the use of prescription opioids has largely spread, which has brought a real progress in the treatment of pain. The long-term use of prescription opioid is sometimes required, and may lead to pharmacological tolerance and withdrawal symptoms, i.e. pharmacological dependence on prescription opioids. Occasionally, this may also lead to misuse of prescription opioids (MPO). MPO preferentially occurs in vulnerable individuals, i.e., those with a young age, history of other addictive or psychiatric disorders, especially anxious and depressive disorders. MPO is associated with numerous complications, including an increased risk of fatal overdose. Prevention of MPO begins before the opioid prescription, with the identification of potential vulnerability factors. A planned and personalized monitoring should be systematically implemented. In vulnerable patients, contractualizing the prescription is warranted. During follow-up, the relevance of the prescription should be regularly reconsidered, according to the benefit observed on pain and the potential underlying signs of MPO. Patients with suspected MPO should be referred early to pain or addiction centers. The treatment of MPO should be based on multidisciplinary strategies, involving both the addiction and pain aspects: progressive opioid withdrawal, non-pharmacological measures against pain, or switching to medication-assisted treatment of addiction (i.e., buprenorphine or methadone).