Effect of single doses of pindolol and d-fenfluramine on flumazenil-induced anxiety in panic disorder patients

Biochemical challenges for testing novel anti-panic drugs in humans

Current medications for panic disorder each carry significant limitations that indicate the need for novel anxiolytics. The high costs and low success rates of drug development demand that testing trials be efficient. Lab panicogenic challenges in humans allow for the rapid biochemical induction of panic symptoms and hence an efficient means of testing potential anti-panic drugs. This paper describes ideal characteristics of lab panicogens, reviews the validity and utility of various biochemical panicogenic agents, identifies key outcome measures for studies of novel anti-panic drugs, and makes broad recommendations for labs wishing to perform such studies. We conclude by presenting a four-tiered hierarchy of panicogens that matches each against ideal characteristics and reflects our recommendations for their laboratory use.

Anxiolytic effects of N-(4,5-dihydro-5-oxo-1,2-dithiolo-[4,3,b]-pyrrole-6-yl)-N-methylformamide, a pyrroloformamide isolated from a marine Streptomyces sp., in adult zebrafish by the 5-HT system

General anxiety disorders are among the most prevalent mental health problems worldwide. The emergence and development of anxiety disorders can be due to genetic (30-50%) or non-genetic (50-70%) factors. Despite medical progress, available pharmacotherapies are sometimes ineffective or can cause undesirable side effects. Thus, it becomes necessary to discover new safe and effective drugs against anxiety. This study evaluated the anxiolytic effect in adult zebrafish (Danio rerio) of a natural pyrroloformamide (PFD), N-(4,5-dihydro-5-oxo-1,2-dithiolo-[4,3,b]-pyrrole-6-yl)-N-methylformamide, isolated from a Streptomyces sp. bacterium strain recovered from the ascidian Eudistoma vannamei. The complete structure of PFD was determined by a detailed NMR analysis, including 1H-13C and 1H-15N-HBMC data. In addition, conformational and DFT computational studies also were performed. A group of fishes (n = 6) was treated orally with PFD (0.1, 0.5 and 1.0 mg/mL; 20 μL) and subjected to locomotor activity and light/dark tests, as well as, acute toxicity 96 h. The involvement of the GABAergic and serotonergic (5-HT) systems was investigated using flumazenil (a silent modulator of GABA receptor) and 5-HT1, 5-HT2A/2C and 5-HTR3A/3B receptors antagonists, known as pizotifen, granisetron and cyproheptadine, respectively. PFD was nontoxic, reduced locomotor activity and promoted the anxiolytic effect in zebrafish. Flumazenil did not inhibit the anxiolytic effect of the PFD via the GABAergic system. This effect was reduced by a pretreatment with pizotifen and granisetron, and was not reversed after treatment with cyproheptadine. Molecular docking and dynamics studies confirmed the interaction of PFD with the 5-HT receptor.Communicated by Ramaswamy H. Sarma.

Pharmacological and Neuromodulatory Treatments for Panic Disorder: Clinical Trials from 2010 to 2018

OBJECTIVE

Treatment for panic disorder (PD) have evolved, although there is still a strong unmet need for more effective and tolerable options. The present study summarizes and discusses recent evidence regarding the pharmacological and neuromodulatory treatment of PD.

METHODS

MEDLINE, Cochrane Library, PsycINFO and Thomson Reuters's Web of Science were searched for clinical trials published between 2010 and 2018. We included all prospective experimental studies including randomized controlled trials (RCT) and other clinical trials with more than 10 patients.

RESULTS

Only 11 articles met the inclusion criteria, including 4 RCT, 3 open clinical trials and 5 comparative clinical trials. RCT demonstrated efficacy of transcranial magnetic stimulation (TMS) in only one of two trials. Neither pindolol nor d-fenfluramine were effective in blocking flumazenil-induced panic attacks. Augmentation with quetiapine was not superior to placebo. Open trials indicated that escitalopram, vortioxetine and TMS may be effective. Comparative trials did not demonstrate superiority from any drug, but confirmed tranylcypromine, paroxetine, clonazepam and alprazolam as effective options.

CONCLUSION

The current study confirmed the efficacy of tranylcypromine, paroxetine, clonazepam, alprazolam and escitalopram. Vortioxetine and TMS, with duration of 4 or more weeks, also seems to be effective. Quetiapine, pindolol and d-fenfluramine were not considered effective compounds.