Safety, Tolerability, Pharmacokinetics, and Concentration-QTc Analysis of Tetrodotoxin: A Randomized, Dose Escalation Study in Healthy Adults.

Tetrodotoxin (TTX) is a highly specific voltage-gated sodium channel (VGSC) blocker in clinical evaluation as a peripheral-acting analgesic for chronic pain. This study presents the first published results of the safety including cardiac liability of TTX at therapeutic-relevant concentrations in twenty-five healthy adults. Randomized, double-blind, placebo-, and positive- (moxifloxacin) controlled study evaluated single ascending doses of 15 µg, 30 µg, and 45 µg TTX over 3 periods with a 7-day washout between each period. Subcutaneous injections of TTX were readily absorbed, reaching maximum plasma concentration (Cmax) within 1.5 h. Both extent of exposure (AUC) and Cmax increased in proportion to dose. No QT prolongation was identified by concentration-QTc analysis and the upper bounds of the two-sided 90% confidence interval of predicted maximum baseline and placebo corrected QTcF (ΔΔQTcF) value did not exceed 10 ms for all tetrodotoxin doses, thereby meeting the criteria of a negative QT study. Safety assessments showed no clinically relevant changes with values similar between all groups and no subject withdrawing due to adverse events. Paresthesia, oral-paresthesia, headache, dizziness, nausea, and myalgia were the most common TEAEs (overall occurrence ≥5%) in the TTX treatment groups. TTX doses investigated in this study are safe, well-tolerated, and lack proarrhythmic proclivity.

Effectiveness of the selective D4 antagonist sonepiprazole in schizophrenia: a placebo-controlled trial.

BACKGROUND: Selective localization of dopamine D(4) receptors in the prefrontal cortex and preferential affinity of clozapine for the dopamine D(4) receptor over the D(2) receptor led to the hypothesis that the superior efficacy of clozapine may be mediated via blockade of the D(4) receptor. This hypothesis was tested by evaluating sonepiprazole, a selective D(4) dopamine antagonist, in schizophrenia patients. METHODS: We treated 467 hospitalized schizophrenia patients with scores of > or = 60 on the Positive and Negative Syndrome Scale (PANSS) with sonepiprazole, olanzapine, or placebo once daily for 6 weeks. The primary efficacy end point was the mean change from baseline in the PANSS total score at 6 weeks. Secondary efficacy end points were the mean change from baseline in the PANSS factor scores, the Brief Psychiatric Rating Scale score, the Clinical Global Impressions Severity of Illness score, and the Calgary Depression Scale score. RESULTS: No statistically significant differences were observed between placebo and any sonepiprazole dose on the primary or any secondary end point after 6 weeks of treatment. Statistically significant differences, favoring olanzapine over placebo, were observed on all efficacy end points but the Calgary Depression Scale. CONCLUSIONS: Sonepiprazole was ineffective for the treatment of patients with schizophrenia.

Strategic challenges in neurotherapeutic pharmaceutical development.

Developing new therapeutics presents formidable economic, scientific, and medical challenges that are exacerbated by special factors in neurotherapeutics development, e.g., the complexity of the CNS with its attendant need to sometimes affect multiple pathways, the lack of clarity of disease etiology, inadequacy of available animal models, and difficulties in defining disease populations and quantifying treatment response. This paper reviews the economic challenges faced by therapeutics developers in general and neurotherapeutics developers in particular. It discusses key scientific challenges, particularly those pertinent to neurotherapeutics development, as a background to proposing a different industrial strategy to drive future therapeutics development. This Biodesign strategy potentially surpasses previous paradigms by incorporating elements such as the use of disease modeling to select better targets and potential therapies, information science-based approaches to enhance small molecule chemistry, exploitation of the potential for biological technologies to rapidly generate mechanistic probes, and development of improved approaches for using animal models and studying human molecules mechanistically and biologically. Synergistic use of these elements can change the overall business model of companies engaged in neurotherapeutics development. The Biodesign paradigm has the potential to both markedly enhance the development of new therapies and to address some of the economic challenges facing healthcare systems and therapeutics developers alike.