Dravet syndrome is a catastrophic pediatric epilepsy with severe intellectual disability, impaired social development and persistent drug-resistant seizures. One of its primary monogenic causes are mutations in Nav1.1 (SCN1A), a voltage-gated sodium channel. Here we characterize zebrafish Nav1.1 (scn1Lab) mutants originally identified in a chemical mutagenesis screen. Mutants exhibit spontaneous abnormal electrographic activity, hyperactivity and convulsive behaviours. Although scn1Lab expression is reduced, microarray analysis is remarkable for the small fraction of differentially expressed genes (~3%) and lack of compensatory expression changes in other scn subunits. Ketogenic diet, diazepam, valproate, potassium bromide and stiripentol attenuate mutant seizure activity; seven other antiepileptic drugs have no effect. A phenotype-based screen of 320 compounds identifies a US Food and Drug Administration-approved compound (clemizole) that inhibits convulsive behaviours and electrographic seizures. This approach represents a new direction in modelling pediatric epilepsy and could be used to identify novel therapeutics for any monogenic epilepsy disorder.

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Drug screening in Scn1a zebrafish mutant identifies clemizole as a potential Dravet syndrome treatment

Dravet syndrome is a catastrophic childhood epilepsy with early-onset seizures, delayed language and motor development, sleep disturbances, anxiety-like behaviour, severe cognitive deficit and an increased risk of fatality. It is primarily caused by de novo mutations of the SCN1A gene encoding a neuronal voltage-activated sodium channel. Zebrafish with a mutation in the SCN1A homologue recapitulate spontaneous seizure activity and mimic the convulsive behavioural movements observed in Dravet syndrome. Here, we show that phenotypic screening of drug libraries in zebrafish scn1 mutants rapidly and successfully identifies new therapeutics. We demonstrate that clemizole binds to serotonin receptors and its antiepileptic activity can be mimicked by drugs acting on serotonin signalling pathways e.g. trazodone and lorcaserin. Coincident with these zebrafish findings, we treated five medically intractable Dravet syndrome patients with a clinically-approved serotonin receptor agonist (lorcaserin, Belviq®) and observed some promising results in terms of reductions in seizure frequency and/or severity. Our findings demonstrate a rapid path from preclinical discovery in zebrafish, through target identification, to potential clinical treatments for Dravet syndrome.

Clemizole and modulators of serotonin signalling suppress seizures in Dravet syndrome

Background
Growing expenditures on prescription medicines represent a major challenge to many health systems. Cap and co-payment policies are intended as an incentive to deter unnecessary or marginal utilisation, and to reduce third-party payer expenditures by shifting parts of the financial burden from insurers to patients, thus increasing their financial responsibility for prescription medicines. Direct patient payment policies include caps (maximum numbers of prescriptions or medicines that are reimbursed), fixed co-payments (patients pay a fixed amount per prescription or medicine), co-insurance (patients pay a percentage of the price), ceilings (patients pay the full price or part of the cost up to a ceiling, after which medicines are free or are available at reduced cost) and tier co-payments (differential co-payments usually assigned to generic and brand medicines). This is the first update of the original review.

Objectives
To determine the effects of cap and co-payment (cost-sharing) policies on use of medicines, healthcare utilisation, health outcomes and costs (expenditures).

Search methods
For this update, we searched the following databases and websites: The Cochrane Central Register of Controlled Trials (CENTRAL) (including the Cochrane Effective Practice and Organisation of Care (EPOC) Group Specialised Register, Cochrane Library; MEDLINE, Ovid; EMBASE, Ovid; IPSA, EBSCO; EconLit, ProQuest; Worldwide Political Science Abstracts, ProQuest; PAIS International, ProQuest; INRUD Bibliography; WHOLIS, WHO; LILACS), VHL; Global Health Library WHO; PubMed, NHL; SCOPUS; SciELO, BIREME; OpenGrey; JOLIS Library Network; OECD Library; World Bank e-Library; World Health Organization, WHO; World Bank Documents & Reports; International Clinical Trials Registry Platform (ICTRP), WHO; ClinicalTrials.gov, NIH. We searched all databases during January and February 2013, apart from SciELO, which we searched in January 2012, and ICTRP and ClinicalTrials.gov, which we searched in March 2014.

Selection criteria
We defined policies in this review as laws, rules or financial or administrative orders made by governments, non-government organisations or private insurers. We included randomised controlled trials, non-randomised controlled trials, interrupted time series studies, repeated measures studies and controlled before-after studies of cap or co-payment policies for a large jurisdiction or system of care. To be included, a study had to include an objective measure of at least one of the following outcomes: medicine use, healthcare utilisation, health outcomes or costs (expenditures).

Data collection and analysis
Two review authors independently extracted data and assessed study limitations. We reanalysed time series data for studies with sufficient data, if appropriate analyses were not reported.

Main results
We included 32 full-text articles (17 new) reporting evaluations of 39 different interventions (one study - Newhouse 1993 - comprises five papers). We excluded from this update eight controlled before-after studies included in the previous version of this review, because they included only one site in their intervention or control groups. Five papers evaluated caps, and six evaluated a cap with co-insurance and a ceiling. Six evaluated fixed co-payment, two evaluated tiered fixed co-payment, 10 evaluated a ceiling with fixed co-payment and 10 evaluated a ceiling with co-insurance. Only one evaluation was a randomised trial. The certainty of the evidence was found to be generally low to very low.

Increasing the amount of money that people pay for medicines may reduce insurers’ medicine expenditures and may reduce patients’ medicine use. This may include reductions in the use of life-sustaining medicines as well as medicines that are important in treating chronic conditions and medicines for asymptomatic conditions. These types of interventions may lead to small decreases in or uncertain effects on healthcare utilisation. We found no studies that reliably reported the effects of these types of interventions on health outcomes.

Authors' conclusions
The diversity of interventions and outcomes addressed across studies and differences in settings, populations and comparisons made it difficult to summarise results across studies. Cap and co-payment polices may reduce the use of medicines and reduce medicine expenditures for health insurers. However, they may also reduce the use of life-sustaining medicines or medicines that are important in treating chronic, including symptomatic, conditions and, consequently, could increase the use of healthcare services. Fixed co-payment with a ceiling and tiered fixed co-payment may be less likely to reduce the use of essential medicines or to increase the use of healthcare services.

Pharmaceutical policies: effects of cap and co-payment on rational use of medicines

Background
We recently identified a compound, clemizole hydrochloride, that inhibits NS4B’s RNA binding and HCV replication. Although significant, clemizole’s antiviral effect is moderate (8μM EC50 against an HCV-2a clone). We hypothesized that combination of clemizole with other anti-HCV agents can increase the antiviral effect over that achieved with each drug alone, and could also decrease emergence of viral resistance.

The Hepatitis C Virus (HCV) NS4B RNA Binding Inhibitor Clemizole Is Highly Synergistic with HCV Protease Inhibitors

Hepatitis C virus (HCV) infection is a global health burden with an estimated 130-170 million chronically infected individuals and is the cause of serious liver diseases such as cirrhosis and hepatocellular carcinoma. HCV NS4B protein represents a validated target for the identification of new drugs to be added to the combination regimen recently approved. During the last years, NS4B has thus been the object of impressive medicinal chemistry efforts, which led to the identification of promising preclinical candidates. In this context, the present review aims to discuss research published on NS4B functional inhibitors focusing the attention on hit identification, hit-to-lead optimization, ADME profile evaluation, and the structure-activity relationship data raised for each compound family taken into account. The information delivered in this review will be a useful and valuable tool for those medicinal chemists dealing with research programs focused on NS4B and aimed at the identification of innovative anti-HCV compounds.

A Journey around the Medicinal Chemistry of Hepatitis C Virus Inhibitors Targeting NS4B: From Target to Preclinical Drug Candidates

Experiments have been described which demonstrate effective prolonged antihistaminic activity and other aspects of the pharmacology of clemizole HC1 (1- p -chloro-benzyl-2-pyrrolidyl-methyl-benzimidazole hydrochloride). A relatively high degree of antihistaminic specificity was observed in both in vitro and in vivo experiments. Clemizole was highly effective in antagonizing histamine aerosol bronchospasm. Spontaneous activity of isolated rabbit ileum and intestinal motility in anesthetized dogs were decreased. There was no significant effect on histamine-induced gastric secretion in chronic gastric fistula dogs. Enhanced responses to epinephrine appear to be due to a sensitization to this amine by the antihistamine. Acute and chronic studies showed a relatively low order of toxicity.

Murray Finkelstein

Papers

Some Aspects of the Pharmacology of Clemizole Hydrochloride