Eckhard Weber

Large Scale Prediction and Testing of Drug Activity on Side-Effect Targets

Discovering the unintended ‘off-targets’ that predict adverse drug reactions is daunting by empirical methods alone. Drugs can act on several protein targets, some of which can be unrelated by conventional molecular metrics, and hundreds of proteins have been implicated in side effects. Here we use a computational strategy to predict the activity of 656 marketed drugs on 73 unintended ‘side-effect’ targets. Approximately half of the predictions were confirmed, either from proprietary databases unknown to the method or by new experimental assays. Affinities for these new off-targets ranged from 1u2009nM to 30u2009μM. To explore relevance, we developed an association metric to prioritize those new off-targets that explained side effects better than any known target of a given drug, creating a drug–target–adverse drug reaction network. Among these new associations was the prediction that the abdominal pain side effect of the synthetic oestrogen chlorotrianisene was mediated through its newly discovered inhibition of the enzyme cyclooxygenase-1. The clinical relevance of this inhibition was borne out in whole human blood platelet aggregation assays. This approach may have wide application to de-risking toxicological liabilities in drug discovery.

Environmental Risk Factors for Chronic Pancreatitis and Pancreatic Cancer

Chronic pancreatitis has long been thought to be mainly associated with immoderate alcohol consumption. The observation that only ∼10% of heavy drinkers develop chronic pancreatitis not only suggests that other environmental factors, such as tobacco smoke, are potent additional risk factors, but also that the genetic component of pancreatitis is more common than previously presumed. Either disease-causing or protective traits have been indentified for mutations in different trypsinogen genes, the gene for the trypsin inhibitor SPINK1, chymotrypsinogen C, and the cystic fibrosis transmembane conductance regulator (CFTR). Other factors that have been proposed to contribute to pancreatitis are obesity, diets high in animal protein and fat, as well as antioxidant deficiencies. For the development of pancreatic cancer, preexisting chronic pancreatitis, more prominently hereditary pancreatitis, is a risk factor. The data on environmental risk factors for pancreatic cancer are, with the notable exception of tobacco smoke, either sparse, unconfirmed or controversial. Obesity appears to increase the risk of pancreatic cancer in the West but not in Japan. Diets high in processed or red meat, diets low in fruits and vegetables, phytochemicals such as lycopene and flavonols, have been proposed and refuted as risk or protective factors in different trials. The best established and single most important risk factor for cancer as well as pancreatitis and the one to clearly avoid is tobacco smoke.

Noninvasive assessment of gastric emptying by near-infrared fluorescence reflectance imaging in mice: pharmacological validation with tegaserod, cisapride, and clonidine.

Noninvasive near-infrared fluorescence reflectance imaging (FRI) is an in vivo technique to assess physiological and molecular processes in the intact organism. Here we describe a method to assess gastric emptying in mice. TentaGel beads with covalently bound cyanine dye (Cy5.5) conjugates as fluorescent probe were administered by oral gavage. The amount of intragastric beads/label was derived from the fluorescence signal intensity measured in a region of interest corresponding to the mouse stomach. The FRI signal intensity decreased as a function of time reflecting gastric emptying. In control mice, the gastric half-emptying time was in agreement with literature data. Pharmacological modulation of gastric motility allowed the evaluation of the sensitivity of the FRI-based method. Gastric emptying was either stimulated or inhibited by treatment with the 5-HT(4) receptor agonists tegaserod (Zelnorm) and cisapride or the alpha(2)-receptor agonist clonidine, respectively. Tegaserod and cisapride dose-dependently accelerated gastric emptying. In contrast, clonidine dose-dependently delayed gastric emptying. In conclusion, FRI using fluorescently labeled beads allows the reliable determination of gastric emptying as well as the assessment of pharmacological interventions. The technique thus offers the potential to characterize molecular targets and pathways involved in physiological regulation and pharmacological modulation of gastric emptying.

1-aminobenzotriazole Modulates Oral Drug Pharmacokinetics through Cytochrome P450 Inhibition and Delay of Gastric Emptying in Rats

The simultaneous effects of the cytochrome P450 inhibitor 1-aminobenzotriazole (ABT) on inhibition of in vivo metabolism and gastric emptying were evaluated with the test compound 7-(3,5-dimethyl-1H-1,2,4-triazol-1-yl)-3-(4-methoxy-2-methylphenyl)-2,6-dimethylpyrazolo[5,1-b]oxazole(NVS-CRF38), a novel corticotropin releasing factor receptor 1 (CRF1) antagonist with low water solubility, and the reference compound midazolam with high water solubility in rats. Pretreatment of rats with 100 mg/kg oral ABT administered 2 hours before a semisolid caloric test meal markedly delayed gastric emptying. ABT increased stomach weights by 2-fold; this is likely attributable to a prosecretory effect because stomach concentrations of bilirubin were comparable in ABT and control groups. ABT administration decreased the initial systemic exposure of orally administered NVS-CRF38 and increased Tmax 40-fold, suggesting gastric retention and delayed oral absorption. ABT increased the initial systemic exposure of midazolam, however for orally (but not subcutaneously) administered midazolam, extensive variability in plasma-concentration time profiles was apparent. Careful selection of administration routes is recommended for ABT use in vivo, variable oral absorption of coadministered compounds can be expected due to a disturbance of gastrointestinal transit.

Development and Validation of a Chronic Pancreatitis Prognosis Score in 2 Independent Cohorts

BACKGROUND & AIMSnThe clinical course of chronic pancreatitis is unpredictable. There is no model to assess disease severity or progression or predict patient outcomes.nnnMETHODSnWe performed a prospective study of 91 patients with chronic pancreatitis; data were collected from patients seen at academic centers in Europe from January 2011 through April 2014. We analyzed correlations between clinical, laboratory, and imaging data with number of hospital readmissions and in-hospital days over the next 12 months; the parameters with the highest degree of correlation were used to develop a 3-stage chronic pancreatitis prognosis score (COPPS). The predictive strength was validated in 129 independent subjects identified from 2 prospective databases.nnnRESULTSnThe mean number of hospital admissions was 1.9 (95% confidence interval [CI], 1.39-2.44) and 15.2 for hospital days (95% CI, 10.76-19.71) for the development cohort and 10.9 for the validation cohort (95% CI, 7.54-14.30) (Pxa0= .08). Based on bivariate correlations, pain (numeric rating scale), level of glycated hemoglobin A1c, level of C-reactive protein, body mass index, and platelet count were used to develop the COPPS system. The patients median COPPS was 8.9 points (range, 5-14). The system accurately discriminated stages of disease severity (low to high): A (5-6 points), Bxa0(7-9), and C (10-15). In Pearson correlation analysis of thexa0development cohort, the COPPS correlated with hospital admissions (0.39; P < .01) and number of hospital days (0.33; Pxa0< .01). The correlation was validated in the validation set (Pearson correlation values of 0.36 and 0.44; P < .01). COPPS did not correlate with results from the Cambridge classification system.nnnCONCLUSIONSnWe developed and validated an easy to use dynamic multivariate scoring system, similar to the Child-Pugh-Score for liver cirrhosis. The COPPS allows objective monitoring of patients with chronic pancreatitis, determining risk for readmission to hospital and potential length of hospital stay.

Preclinical metabolism and pharmacokinetics of NVS-CRF38, a potent and orally bioavailable corticotropin-releasing factor receptor 1 antagonist

Abstract 1.u2002The pharmacokinetic properties and metabolism of NVS-CRF38 [7-(3,5-dimethyl-1H-1,2,4-triazol-1-yl)-3-(4-methoxy-2-methylphenyl)-2,6-dimethylpyrazolo[5,1-b]oxazole], a novel corticotropin-releasing factor receptor 1 (CRF1) antagonist, were determined in vitro and in animals. 2.u2002NVS-CRF38 undergoes near complete absorption in rats and dogs. In both species the compound has low hepatic extraction and is extensively distributed to tissues. 3.u2002In rat and human hepatic microsomes and cryopreserved hepatocytes from rat, dog, monkey and human, NVS-CRF38 was metabolised to form O-desmethyl NVS-CRF38 (M7) and several oxygen adducts (M1, M3, M4, M5 and M6). In hepatocytes further metabolites were observed, specifically the carboxylic acid (M2) and conjugates (sulphate and glucuronide) of M7. 4.u2002Formation of primary metabolites in hepatocytes was blocked by the cytochrome P450 enzyme (P450) suicide inhibitor 1-aminobenzotriazole, implicating P450 enzymes in the primary metabolism of this compound. 5.u2002NVS-CRF38 is weakly bound to plasma proteins from rat (fubu2009=u20090.19), dog (fubu2009=u20090.25), monkey (fubu2009=u20090.20) and humans (fubu2009=u20090.23). Blood-to-plasma partition for NVS-CRF38 approaches unity in rat and human blood. 6.u2002The hepatic clearance of NVS-CRF38 in humans is predicted to be low (extraction ratiou2009∼u20090.2) based on scaling from drug depletion profiles in hepatic microsomes.

Tough Composite Hydrogels with High Loading and Local Release of Biological Drugs

Hydrogels are under active development for controlled drug delivery, but their clinical translation is limited by low drug loading capacity, deficiencies in mechanical toughness and storage stability, and poor control over the drug release that often results in burst release and short release duration. This work reports a design of composite clay hydrogels, which simultaneously achieve a spectrum of mechanical, storage, and drug loading/releasing properties to address the critical needs from translational perspectives. The clay nanoparticles provide large surface areas to adsorb biological drugs, and assemble into microparticles that are physically trapped within and toughen hydrogel networks. The composite hydrogels demonstrate feasibility of storage, and extended release of large quantities of an insulin-like growth factor-1 mimetic protein (8 mg mL-1 ) over four weeks. The release rate is primarily governed by ionic exchange and can be upregulated by low pH, which is typical for injured tissues. A rodent model of Achilles tendon injury is used to demonstrate that the composite hydrogels allow for highly extended and localized release of biological drugs in vivo, while demonstrating biodegradation and biocompatibility. These attributes make the composite hydrogel a promising system for drug delivery and regenerative medicine.