Mechanisms of Drug-Induced Proarrhythmia in Clinical Practice.

Mechanisms of drug-induced proarrhythmia in clinical practice.

World J Cardiol. 2013 Jun 26; 5(6): 175-185
Konstantopoulou A, Tsikrikas S, Asvestas D, Korantzopoulos P, Letsas KP

Drug-induced proarrhythmia represents a great challenge for those involved in the development of novel pharmaceuticals and in the regulatory bodies for drug approval as well as for the prescribing clinicians. Our understanding of the mechanisms that underlie drug-induced proarrhythmia has grown dramatically over the last two decades. A growing number of cardiac and non-cardiac agents have been shown to alter cardiac repolarization predisposing to fatal cardiac arrhythmias such as ventricular tachycardia or ventricular fibrillation and sudden cardiac death. These agents may induce the phenotype of long QT syndrome and less commonly of short QT syndrome and Brugada syndrome (BS). Although, genetic susceptibility underlie drug-induced proarrhythmia in certain cases, current data are limited regarding this topic. The present review surveys the current published literature on the mechanisms and the offending medical agents that predispose to drug-induced long QT syndrome, short QT syndrome and BS. Drug-induced proarrhythmia should be considered as a predictor of sudden cardiac death and should prompt critical re-evaluation of the risks and benefits of the suspicious medication. Survivors of drug-induced proarrhythmia and family members require careful examination and possibly genetic testing for the presence of a channelopathy. Treating physicians are advised to follow the lists of agents implicated in drug-induced proarrhythmia in order to minimize the risk of arrhythmia and sudden cardiac death. HubMed – drug

Targeted Therapy of Advanced Gallbladder Cancer and Cholangiocarcinoma with Aggressive Biology: Eliciting Early Response Signals from Phase 1 trials.

Oncotarget. 2013 Jan; 4(1): 153-162
Subbiah IM, Subbiah V, Tsimberidou AM, Naing A, Kaseb AO, Javle M, Fu S, Hong DS, Piha-Paul S, Wheler JJ, Hess KR, Janku F, Falchook GS, Wolff RA, Kurzrock R

Patients with advanced cholangiocarcinoma (CC) and gallbladder carcinoma (GC) have few therapeutic options for relapsed disease.Given the overall poor prognosis in this population and the availability of novel targeted therapies, we systematically analyzed the characteristics and outcomes for GC and CC patients treated on phase I trials with an emphasis on targeted agents and locoregional therapies.Of 40 treated patients (GC=6; CC=34; median age, 60 years), 8 (20%) had stable disease (SD) > 6 months, 3 (8%) partial response (PR), on protocols with hepatic arterial drug infusion and anti-angiogenic, anti-HER-2/neu or novel MAPK/ERK kinase (MEK) inhibitors. Median progression-free survival (PFS) on phase I trials was 2.0 months (95% CI 1.7, 2.8) versus 3.0 months (95% CI 2.4, 5.0), 3.0 months (95% CI 2.3, 4.6), and 3.0 months (95% CI 2.4, 3.9) for their first-, second-, and last-line FDA-approved therapy. In univariate analysis, >3 metastatic sites, elevated alanine aminotransferase (ALT) (>56IU/L), serum creatinine (>1.6mg/dL), and CA19-9 (>35U/mL) were associated with a shorter PFS. Mutational analysis revealed mutation in the KRAS oncogene in 2 of 11 patients (18%). The SD >6 months/PR rate of 28% was seen with hepatic arterial infusion of oxaliplatin, and inhibitors of angiogenesis, HER-2/neu or MEK.The PFS in phase I trials was similar to that of the first, second, and last-line therapy (P=0.95, 0.98, 0.76, respectively) with FDA-approved agents given in the advanced setting, emphasizing a role for targeted agents in a clinical trials setting as potentially valuable therapeutic options for these patients. HubMed – drug

Discovery and Preliminary SAR of Arylpiperazines as Novel, Brainpenetrant Antiprion Compounds.

ACS Med Chem Lett. 2013 Apr 11; 4(4): 397-401
Li Z, Gever J, Rao S, Widjaja K, Prusiner SB, Silber BM

Prion diseases are a group of fatal neurodegenerative disorders that include Creutzfeldt-Jakob disease (CJD) and kuru in humans, BSE in cattle, and scrapie in sheep. Such illnesses are caused by the conversion and accumulation of a misfolded pathogenic isoform (termed PrP(Sc)) of a normally benign, host cellular protein, denoted PrP(C). We employed high-throughput screening (HTS) ELISAs to evaluate compounds for their ability to reduce the level of PrP(Sc) in Rocky Mountain Laboratory (RML) prion-infected mouse neuroblastoma cells (ScN2a-cl3). Arylpiperazines were among the active compounds identified but the initial hits suffered from low potency and poor drug-likeness. The best of those hits, such as 1, 7, 13, and 19, displayed moderate antiprion activity with EC50 values in the micromolar range. Key analogs were designed and synthesized based on the SAR, with analogs 41, 44, 46, and 47 found to have sub-micromolar potency. Analogs 41 and 44 were able to penetrate the blood-brain barrier (BBB) and achieved excellent drug concentrations in the brains of mice after oral dosing. These compounds represent good starting points for further lead optimization in our pursuit of potential drug candidates for the treatment of prion diseases. HubMed – drug

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