Netupitant is a new, selective NK1 receptor antagonist under development for the prevention of chemotherapy-induced nausea and vomiting. Two studies were conducted to evaluate the brain receptor occupancy (RO) and disposition (ADME) of netupitant in humans. Positron emission tomography (PET) imaging with the NK1 receptor-binding–selective tracer [11C]-GR205171 was used to evaluate the brain penetration of different doses of netupitant (100, 300, and 450 mg) and to determine the NK1-RO duration. A NK1-RO of 90% or higher was achieved with all doses in the majority of the tested brain regions at Cmax, with a long duration of RO. The netupitant minimal plasma concentration predicted to achieve a NK1-RO of 90%, C90%, in the striatum was 225 ng/mL; after administration of netupitant 300 mg, concentrations exceeded the C90%. In the ADME study, a single nominal dose of [14C]-netupitant 300 mg was used to assess its disposition. Absorption was rapid and netupitant was extensively metabolized via Phase I and II hepatic metabolism. Elimination of >90% was predicted at day 29 and was principally via hepatic/biliary route (>85%) with a minor contribution of the renal route (<5%). In conclusion, these studies demonstrate that netupitant is a potent agent targeting NK1 receptors with long lasting RO. In addition, netupitant is extensively metabolized and is mainly eliminated through the hepatic/biliary route and to a lesser extent via the kidneys.

Background Constipation and L-dopa-induced gastric dysmotility are common gastrointestinal (GI) symptoms in Parkinson’s disease (PD). We investigate the novel ghrelin agonist, HM01 influence on GI motor dysfunctions in 6-hydroxydopamine (6-OHDA) rats. Methods HM01 pharmacological profiles were determined in vitro and in vivo in rats. We assessed changes in fecal output and water content, and gastric emptying (GE) in 6-OHDA rats treated or not with orogastric (og) HM01 and L-dopa/carbidopa (LD/CD, 20/2 mg kg−1). Fos immunoreactivity (ir) cells in specific brain and lumbosacral spinal cord were quantified. Key results HM01 displayed a high binding affinity to ghrelin receptor (Ki: 1.42 ± 0.36 nM), 4.3±1.0 h half-life and high brain/plasma ratio. 6-OHDA rats had reduced daily fecal output (22%) and water intake (23%) compared to controls. HM01 (3 and 10 mg kg−1) similarly reversed the decreased 4-h fecal weight and water content in 6-OHDA rats. Basal GE was not modified in 6-OHDA rats, however, LD/CD (once or daily for 8 days) delayed GE in 6-OHDA and control rats that was prevented by HM01 (3 mg kg−1 acute or daily before LD/CD). HM01 increased Fos-ir cell number in the area postrema, arcuate nucleus, nucleus tractus solitarius and lumbosacral intermediolateral column of 6-OHDA rats where 6-OHDA had a lowering effect compared to controls. Conclusions & Inferences 6-OHDA rats display constipation- and adipsia-like features of PD and L-dopa-inhibited GE. The new orally active ghrelin agonist, HM01 crosses the blood brain barrier and alleviates these alterations suggesting a potential benefit for PD with GI disorders.

Infections caused by hepatitis C virus (HCV) are a significant world health problem for which novel therapies are in urgent demand. Compounds that block replication of subgenomic HCV RNA in liver cells are of interest because of their demonstrated antiviral effect in the clinic. In followup to our recent report that indole-N-acetamides (e.g., 1) are potent allosteric inhibitors of the HCV NS5B polymerase enzyme, we describe here their optimization as cell-based inhibitors. The crystal structure of 1 bound to NS5B was a guide in the design of a two-dimensional compound array that highlighted that formally zwitterionic inhibitors have strong intracellular potency and that pregnane X receptor (PXR) activation (an undesired off-target activity) is linked to a structural feature of the inhibitor. Optimized analogues devoid of PXR activation (e.g., 55, EC(50) = 127 nM) retain strong cell-based efficacy under high serum conditions and show acceptable pharmacokinetics parameters in rat and dog.

The application of a phosphoramidate prodrug approach to 2'-C-methylcytidine (NM107), the first nucleoside inhibitor of the hepatitis C virus (HCV) NS5B polymerase, is reported. 2'-C-Methylcytidine, as its valyl ester prodrug (NM283), was efficacious in reducing the viral load in patients infected with HCV. Several of the phosphoramidates prepared demonstrated a 10- to 200-fold superior potency with respect to the parent nucleoside in the cell-based replicon assay. This is due to higher levels of 2'-C-methylcytidine triphosphate in the cells. These prodrugs are efficiently activated and converted to the triphosphate in hepatocytes of several species. Our SAR studies ultimately led to compounds that gave high levels of NTP in hamster and rat liver after subcutaneous dosing and that were devoid of the toxic phenol moiety usually found in ProTides.

HILIC LC-MS for the determination of 29-C-methylcytidine-triphosphate in rat liverA very accurate and selective LC-MS/MS method was developed and validated for the quantification of 29-C-modified nucleoside triphosphate in liver tissue samples. An efficient pretreatment procedure of liver tissue samples was developed, using a fully automated SPE procedure with 96-well SPE plate (weak anion exchange sorbent, 30 mg). Nucleotide hydrophilic interaction chromatography has been performed on an aminopropyl column (100 mm62.0 mm, 3 lm) using a gradient mixture of ACN and ACN/water (5:95 v/v) with 20 mM ammonium acetate at pH 9.45 as mobile phase at 300 lL/min flow rate. The 29-C-modified nucleoside triphosphate was detected in the negative ESI mode in multiple reaction monitoring (MRM) mode. Calibration curve was linear over the 0.05 -50 lM concentration range. Satisfying results, confirming the high reliability of the established LC-MS/MS method, were obtained for intraday precision (CV = 2.5 -9.1%) and accuracy (92.6 -94.8%) and interday precision (CV = 9.6 -11.5%) and accuracy (94.4 -102.4%) as well as for recovery (82.0 -112.6%) and selectivity. The method has been successfully applied for pharmacokinetic studies of 29-C-methyl-cytidine-triphosphate in liver tissue samples.

Infections caused by hepatitis C virus (HCV) are a significant world health problem for which novel therapies are in urgent demand. The polymerase of HCV is responsible for the replication of viral genome and has been a prime target for drug discovery efforts. Here, we report on the further development of tetracyclic indole inhibitors, binding to an allosteric site on the thumb domain. Structure-activity relationship (SAR) studies around an indolo-benzoxazocine scaffold led to the identification of compound 33 (MK-3281), an inhibitor with good potency in the HCV subgenomic replication assay and attractive molecular properties suitable for a clinical candidate. The compound caused a consistent decrease in viremia in vivo using the chimeric mouse model of HCV infection.

The gastric hormone ghrelin positively affects energy balance by increasing food intake and reducing energy expenditure. Ghrelin mimetics are a possible treatment against cancer anorexia-cachexia syndrome (CACS). This study aimed to characterize the action of the nonpeptidergic ghrelin receptor agonist HM01 on neuronal function, energy homeostasis and muscle mass in healthy rats and to evaluate its possible usefulness for the treatment of CACS in a rat tumor model. Using extracellular single-unit recordings, we tested whether HM01 mimics the effects of ghrelin on neuronal activity in the arcuate nucleus (Arc). Furthermore, we assessed the effect of chronic HM01 treatment on food intake (FI), body weight (BW), lean and fat volumes, and muscle mass in healthy rats. Using a hepatoma model, we investigated the possible beneficial effects of HM01 on tumor-induced anorexia, BW loss, muscle wasting, and metabolic rate. HM01 (10(-7)-10(-6) M) mimicked the effect of ghrelin (10(-8) M) by increasing the firing rate in 76% of Arc neurons. HM01 delivered chronically for 12 days via osmotic minipumps (50 μg/h) increased FI in healthy rats by 24%, paralleled by increased BW, higher fat and lean volumes, and higher muscle mass. Tumor-bearing rats treated with HM01 had 30% higher FI than tumor-bearing controls and were protected against BW loss. HM01 treatment resulted in higher muscle mass and fat mass. Moreover, tumor-bearing rats reduced their metabolic rate following HM01 treatment. Our studies substantiate the possible therapeutic usefulness of ghrelin receptor agonists like HM01 for the treatment of CACS and possibly other forms of disease-related anorexia and cachexia.

Our study demonstrates therapeutic actions of novel ghrelin receptor inverse agonists, suggesting a potential to treat obesity-related metabolic disorders including diabetes mellitus.