Aims Pharmacotherapy for methamphetamine dependence has not yet been developed in Japan or elsewhere in the world. Ifenprodil is a blocker of G protein‐activated inwardly rectifying potassium channels that play a key role in the mechanism of action of addictive substances. Our aim is to examine the safety, efficacy, and outcomes of ifenprodil for the treatment of methamphetamine dependence in a randomized, double‐blind, placebo‐controlled trial. Methods The recruitment of outpatients with methamphetamine dependence began in January 2018. The patients will be randomized into three arms: placebo, 60 mg/d ifenprodil, or 120 mg/d ifenprodil. Placebo or ifenprodil will be taken for 84 days. We will use Cerocral fine granule 4%® (ifenprodil tartrate). Follow‐up assessments will be conducted for 84 d after the drug administration period. All of the patients will be assessed by self‐administered questionnaires and urine tests. The primary outcome will be the presence or absence of methamphetamine use during the 84‐day administration period in the 120 mg/d ifenprodil and placebo groups. Secondary outcomes will include the number of days and percentage of days of abstinence from methamphetamine use, positive urine for methamphetamine, relapse risk, and drug craving. Discussion This study is the first clinical trial of ifenprodil treatment for methamphetamine dependence and is designed as an intervention test with off‐label drug use. The present study is expected to provide evidence of the effects of ifenprodil treatment on methamphetamine dependence. Trial registry This trial was registered in the UMIN clinical trial registry (UMIN000030849; date of registration: January 17, 2018).

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Long-term use of benzodiazepines (BZD) is not recommended for the treatment of anxiety disorders. Cognitive behavioral therapy (CBT) is an effective treatment option for discontinuation of BZD in patients with anxiety disorders. This systematic review and meta-analysis sought to clarify whether CBT is effective for discontinuing BZD anxiolytics in patients with anxiety disorders. This study was preregistered with PROSPERO (registration number: CRD42019125263). A literature search of major electronic databases was conducted in December 2018. Three randomized controlled trials were included in this review, and meta-analyses were performed. The proportion of discontinuing BZD anxiolytics was significantly higher in the CBT plus gradual tapering group than in the gradual tapering alone group, both in the short term (3 months after allocation; number needed to treat: 3.2, 95% confidence interval [CI]: 2.1 to 7.1; risk ratio: 1.96, 95%CI: 1.29 to 2.98, P = 0.002, three studies) and long term (6 to 12 months after allocation; number needed to treat: 2.8, 95%CI: 1.9 to 5.3; risk ratio: 2.16, 95%CI: 1.41 to 3.32, P = 0.0004, three studies). CBT may be effective for discontinuing BZD anxiolytics, both in the short term and in the long term after the allocation. Further studies with larger sample sizes are necessary to draw definitive conclusions regarding the efficacy and safety of CBT for discontinuing BZD anxiolytics in patients with anxiety disorders.

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