Development of a prodrug of hydantoin based TACE inhibitor.

Our research on hydantoin based TNF-α converting enzyme (TACE) inhibitors led to fused bi-heteroaryl hydantoin series that demonstrate sub-nanomolar potency (Ki) as well as excellent activity in human whole blood (hWBA). However, lead compound 2 posed some formulation challenges which prevented it for further development. A prodrug approach was investigated to address this issue. The pivalate prodrug 3 can be formulated as stable neutral form and demonstrated improved DMPK properties when compared with parent compound.

Synthesis, Radiolabeling, and Biological Evaluation of (R)- and (S)-2-Amino-5-[(18)F]fluoro-2-methylpentanoic Acid ((R)-, (S)-[(18)F]FAMPe) as Potential Positron Emission Tomography Tracers for Brain Tumors.

A novel (18)F-labeled α,α-disubstituted amino acid-based tracer, 2-amino-5-[(18)F]fluoro-2-methylpentanoic acid ([(18)F]FAMPe), has been developed for brain tumor imaging with a longer alkyl side chain than previously reported compounds to increase brain availability via system L amino acid transport. Both enantiomers of [(18)F]FAMPe were obtained in good radiochemical yield (24-52% n = 8) and high radiochemical purity (>99%). In vitro uptake assays in mouse DBT gliomas cells revealed that (S)-[(18)F]FAMPe enters cells partly via sodium-independent system L transporters and also via other nonsystem A transport systems including transporters that recognize glutamine. Biodistribution and small animal PET/CT studies in the mouse DBT model of glioblastoma showed that both (R)- and (S)-[(18)F]FAMPe have good tumor imaging properties with the (S)-enantiomer providing higher tumor uptake and tumor to brain ratios. Comparison of the SUVs showed that (S)-[(18)F]FAMPe had higher tumor to brain ratios compared to (S)-[(18)F]FET, a well-established system L substrate.

Carcinogenicity assessment of the pan-caspase inhibitor, emricasan, in Tg.rasH2 mice.

Emricasan, formerly IDN-6556, is a small molecule currently being evaluated in clinical trials to reduce hepatic injury and liver fibrosis. Since emricasan is an irreversible pan-caspase inhibitor that potently inhibits caspase-mediated apoptosis and inflammation, its carcinogenic potential was evaluated in a humanized mouse model. Tg.rasH2 mice received LabDiet formulated with 0, 10, 25, and 75mg/kg/day of emricasan, for 26weeks. At terminal sacrifice, blood was collected for clinical pathology analysis and tissues were collected, processed, and evaluated microscopically. There were no treatment related deaths or overt signs of toxicity for the duration of the study. There was no evidence of a carcinogenic effect in the peripheral blood leukocyte counts. Liver microgranulomas, which are background lesions, were slightly increased, especially in males. Increases in the incidence of the activated germinal centers were seen in the spleens and mesenteric lymph nodes of males and females, and in the mandibular lymph nodes of male mice. Atrophy of ovaries and testicular degeneration were also seen in emricasan treated animals. Although several non-neoplastic lesions were observed, there was no evidence of emricasan-related tumor formation in any tissue. In addition, the non-neoplastic lesions were not considered pre-neoplastic. Thus, emricasan is not considered carcinogenic.

Exploring the roles of UGT1A1 and UGT1A3 in oral clearance of GSK2190915, a 5-lipoxygenase-activating protein inhibitor.

Pharmacokinetic variability in drug exposure is a concern for all compounds in development including those for the treatment of asthma and other respiratory disorders. Substantial variability in the oral clearance of GSK2190915, a 5-lipoxygenase-activating protein inhibitor that attenuates the production of leukotriene B4 and cysteinyl leukotrienes, is largely unaccounted for by clinical variables. A study of 41 patients, 78% (32/41) of whom were non-Hispanic whites, with mild to moderate asthma identified an association of UGT1A1*28 and UGT1A3*2 with the oral clearance of GSK2190915 (P=3.8×10⁻4 and 1.2×10⁻5, respectively). However, in a subsequent replication study of 403 non-Hispanic white patients with asthma, we failed to observe a statistically significant association between oral clearance of GSK2190915 and either UGT1A1*28 or UGT1A3*2 (P>0.05). Therefore, genetic effects that could explain the systemic exposure level variability of GSK2190915 were not identified.

Pharmacodynamic and clinical endpoints for functional colonic disorders: statistical considerations.

BACKGROUND: Intra- and inter-subject coefficients of variation (COV) of scintigraphic colonic transit (SCT) are well characterized. SCT response to therapy predicts clinical efficacy of experimental medications in lower functional gastrointestinal disorders (FGID). AIM: To compare COVs for bowel function with pharmacodynamic (PD) colonic transit geometric center (GC) as endpoints in lower FGID studies. METHODS: We evaluated data from placebo arm of 9 phase IIA, parallel-group, clinical trials of PD effects of linaclotide, dexloxiglumide, renzapride, elobixibat, ROSE 010, and chenodeoxycholate in lower FGID with constipation, and pexacerafont, VSL#3, and colesevelam in lower FGID with diarrhea. Patients completed daily diaries for at least 7 days of stool frequency, consistency (7-point Bristol Stool Form Scale), and ease of passage (7-point scale from manual disimpaction to incontinence). Seventeen patients received placebo in 2 separate studies allowing assessment of intra-patient COVs. We calculated sample sizes required to demonstrate a 30 % effect size for colonic transit, stool frequency, consistency and ease of passage for patients with lower FGID with constipation and, separately, diarrhea. RESULTS: COV(inter) from 87 patients and COV(intra) from 17 patients are reported. Generally, COV(intra) is somewhat greater than COV(inter). The COVs for PD endpoints are lower than for clinical endpoints; however, clinically relevant effects can be identified with modest (~50 %) increases in the sample size using parallel-group design studies. CONCLUSION: Phase IIA studies that incorporate clinical and PD endpoints are feasible in lower FGID associated with constipation or diarrhea. Crossover design would require lower sample size for most endpoints compared to parallel-group studies.

PET imaging-based evaluation of hepatobiliary transport in humans with (15R)-11C-TIC-Me.

UNLABELLED: It is well accepted that drug transporters play a pivotal role in hepatobiliary excretion of anionic drugs, in which drug-drug interactions and genetic polymorphisms are known to cause variations. However, PET probes for in vivo functional characterization of these transporters have not been established yet. We used PET to investigate hepatic uptake and subsequent canalicular efflux of (11)C-labeled (15R)-16-m-tolyl-17,18,19,20-tetranorisocarbacyclin methyl ester [(15R)-(11)C-TIC-Me)] in healthy subjects. METHODS: Serial PET scans of the abdominal region in healthy male subjects were obtained with or without the organic anion-transporting polypeptide (OATP) inhibitor rifampicin after intravenous injection of (15R)-(11)C-TIC-Me as a radiotracer. Venous blood samples and PET images were obtained at frequent intervals up to 30 min after administration of the PET tracer. Dynamic imaging data were evaluated by integration plots of data collected for 2-10 min and for 10-30 min after tracer administration for the determination of tissue uptake clearance and biliary efflux clearance, respectively. RESULTS: After rapid hydrolysis in blood, the acid form-(11)C-labeled (15R)-16-m-tolyl-17,18,19,20-tetranorisocarbacyclin [(15R)-(11)C-TIC]-accumulated in the liver (37% of the dose by 17 min), and the radioactivity was then excreted into the bile (6.2% by 30 min). Rifampicin (600 mg by mouth), a potent OATP inhibitor, significantly reduced the radioactivity excreted into the bile (by 44%) by inhibiting both uptake (by 45%) and subsequent canalicular efflux (by 62%). (15R)-(11)C-TIC is an in vitro substrate of OATP1B1 and OATP1B3, and clinically relevant concentrations of rifampicin inhibited uptake by OATP1B1 and OATP1B3. These results demonstrated that in humans, (15R)-(11)C-TIC-associated radioactivity is excreted into the bile by organic anion transport systems. CONCLUSION: We demonstrated that PET image analysis with (15R)-(11)C-TIC-Me is useful for investigating variations in OATP function in the human hepatobiliary transport system.

Chronic treatment with a novel γ-secretase modulator, JNJ-40418677, inhibits amyloid plaque formation in a mouse model of Alzheimer's disease.

BACKGROUND AND PURPOSE: γ-Secretase modulators represent a promising therapeutic approach for Alzheimer's disease (AD) because they selectively decrease amyloid ß 42 (Aß42), a particularly neurotoxic Aß species that accumulates in plaques in the brains of patients with AD. In the present study, we describe the in vitro and in vivo pharmacological properties of a potent novel γ-secretase modulator, 2-(S)-(3,5-bis(4-(trifluoromethyl)phenyl)phenyl)-4-methylpentanoic acid (JNJ-40418677). EXPERIMENTAL APPROACH: The potency and selectivity of JNJ-40418677 for Aß reduction was investigated in human neuroblastoma cells, rat primary neurones and after treatment with single oral doses in non-transgenic mouse brains. To evaluate the effect of JNJ-40418677 on plaque formation, Tg2576 mice were treated from 6 until 13 months of age via the diet. KEY RESULTS: JNJ-40418677 selectively reduced Aß42 secretion in human neuroblastoma cells and rat primary neurones, but it did not inhibit Notch processing or formation of other amyloid precursor protein cleavage products. Oral treatment of non-transgenic mice with JNJ-40418677 resulted in an excellent brain penetration of the compound and a dose- and time-dependent decrease of brain Aß42 levels. Chronic treatment of Tg2576 mice with JNJ-40418677 reduced brain Aß levels, the area occupied by plaques and plaque number in a dose-dependent manner compared with transgenic vehicle-treated mice. CONCLUSIONS AND IMPLICATIONS: JNJ-40418677 selectively decreased Aß42 production, showed an excellent brain penetration after oral administration in mice and lowered brain Aß burden in Tg2576 mice after chronic treatment. JNJ-40418677 therefore warrants further investigation as a potentially effective disease-modifying therapy for AD.

Pharmacology of AM803, a novel selective five-lipoxygenase-activating protein (FLAP) inhibitor in rodent models of acute inflammation.

We evaluated the in vivo pharmacological properties of AM803 3-[3-tert-butylsulfanyl-1-[4-(6-ethoxy-pyridin-3-yl)-benzyl]-5-(5-methyl-pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic acid, a selective five-lipoxygenase-activating protein (FLAP) inhibitor, using rat and mouse models of acute inflammation. Oral administration of AM803 (1 mg/kg) resulted in sustained inhibition of ex vivo ionophore-challenged whole blood LTB4 biosynthesis with >90% inhibition for up to 12 h and an EC50 of approximately 7 nM. When rat lungs were challenged in vivo with calcium-ionophore, AM803 inhibited LTB4 and cysteinyl leukotriene (CysLT) production with ED50s of 0.12 mg/kg and 0.37 mg/kg, respectively. The inhibition measured 16 h following a single oral dose of 3 mg/kg was 86% and 41% for LTB4 and CysLTs, respectively. In an acute inflammation setting, AM803 dose-dependently reduced LTB4, CysLTs, plasma protein extravasation and neutrophil influx induced by peritoneal zymosan injection. Finally, AM803 increased survival time in mice exposed to a lethal intravenous injection of platelet activating factor (PAF). The magnitude of effect was similar to that of an inhibitor of five-lipoxygenase (5-LO) and LTA4 hydrolase but superior to a leukotriene CysLT1 receptor antagonist. In summary, AM803 is a novel, potent and selective FLAP inhibitor that has excellent pharmacodynamic properties in vivo and is effective in animal models of acute inflammation and in a model of lethal shock.

Evaluation of stereoselective anticonvulsant, teratogenic, and pharmacokinetic profile of valnoctylurea (capuride): a chiral stereoisomer of valproic acid urea derivative.

PURPOSE: The purpose of this study was to evaluate the stereoselective anticonvulsant activity, neurotoxicity, pharmacokinetics, and teratogenic potential of two stereoisomers of valnoctylurea (VCU), a central nervous system (CNS)-active urea derivative of valnoctic acid, which is a constitutional isomer of valproic acid (VPA). METHODS: VCU stereoisomers (2S,3S)-VCU and (2R,3S)-VCU were synthesized. Their anticonvulsant activity was determined and compared to VPA and racemic-VCU in rats utilizing the maximal electroshock seizure (MES) and the subcutaneous pentylenetetrazole (scMet) tests. Neurotoxicity was determined in rats using the positional sense test, muscle tone test, and gait and stance test. The induction of neural tube defects (NTDs) by VCU stereoisomers was evaluated in a mouse strain highly susceptible to VPA-induced teratogenicity. The pharmacokinetics of VCU was studied in a stereoselective manner following intraperitoneal (i.p.) administration to rats. RESULTS: (2S,3S)-VCU and (2R,3S)-VCU median effective dose ED(50) values were 29 mg/kg [95% confidence interval (CI) = 8-60 mg/kg] and 42 mg/kg (95% CI = 36-51 mg/kg) (MES) and 22 mg/kg (95% CI = 13-51 mg/kg) and 12 mg/kg (95%CI = 7-21 mg/kg) (scMet), respectively. (2S,3S)-VCU was more potent and had a wider safety margin (p < 0.05), defined as the protective index (PI = TD(50)/ED(50)), at both the MES (PI > 17) and scMet (PI > 23) tests than racemic-VCU or (R,S)-VCU (PI = 2.8 and 9.9, respectively). VCU stereoisomers caused NTDs at doses >4 times that of their anticonvulsant ED(50) values. At a dose of 112 mg/kg, (2R,3S)-VCU was nonteratogenic and less embryotoxic than its stereoisomer (2S,3S)-VCU. No stereoselective pharmacokinetics was observed following intraperitoneal dosing of racemic-VCU to rats. VCU was mainly eliminated by metabolism with a half-life of 2 h. CONCLUSIONS: VCU anticonvulsant activity and wide PI values make it a potential candidate for development as a new, potent antiepileptic drug (AED).

Novel selective inhibitors of neutral endopeptidase for the treatment of female sexual arousal disorder. Synthesis and activity of functionalized glutaramides.

Female sexual arousal disorder (FSAD) is a highly prevalent sexual disorder affecting up to 40% of women. We describe herein our efforts to identify a selective neutral endopeptidase (NEP) inhibitor as a potential treatment for FSAD. The rationale for this approach, together with a description of the medicinal chemistry strategy, lead compounds, and SAR investigations are detailed. In particular, the strategy of starting with the clinically precedented selective NEP inhibitor, Candoxatrilat, and targeting low molecular weight and relatively polar mono-carboxylic acids is described. This led ultimately to the prototype development candidate R-13, for which detailed pharmacology and pharmacokinetic parameters are presented.(1)

A potent and selective inhibitor of group IIa secretory phospholipase A2 protects rats from TNBS-induced colitis.

Secretory phospholipase A(2) (sPLA(2)) enzymes have been implicated in the pathogenesis of human inflammatory bowel disease (IBD). In this study we compared the efficacy of a potent, new and highly selective inhibitor of group IIa human sPLA(2) enzyme (5-(4-benzyloxyphenyl)-4S-(7-phenylheptanoylamino)-pentanoic acid; sPLA(2)I), with that of sulfasalazine, in a rat model of trinitrobenzene sulfonic acid (TNBS)-induced colitis. Following a single oral dose of sPLA(2)I (5 mg/kg), pharmacoactive levels of drug were detected in the serum within 15 min and for up to 24 h by liquid chromatography mass spectrometry analysis. Rats treated with sPLA(2)I (5 mg/kg/day) prior to induction of colitis were significantly healthier than TNBS-alone rats, as shown by reduced mortality, improved food intake and increased body weight, and significantly reduced colon myeloperoxidase levels, edema, tumour necrosis factor-alpha levels, and colon macroscopic pathology scores after 8 days. Rats pretreated with sulfasalazine (100 mg/kg/day) also had reduced disease expression markers similar to the sPLA(2)I, but exhibited no improvement in colon edema. This study supports a role for the group IIa sPLA(2) enzyme in pathology associated with the TNBS rat model of IBD, and suggests a possible therapeutic application for selective inhibitors of group IIa sPLA(2) inhibitors in the treatment of IBD.

Characterization of dexloxiglumide in vitro biopharmaceutical properties and active transport.

The objective of this work was to characterize dexloxiglumide biopharmaceutical properties in vitro and relate these characteristics to its in vivo absorption performance, and to assess dexloxiglumide interaction with P-glycoprotein (P-gp) and MRP1 to anticipate its drug interaction potential. Dexloxiglumide aqueous solubility was moderate and pH dependent. Dexloxiglumide exhibited moderate Caco-2 permeability that was polarized, concentration dependent, and pH dependent. The apical-to-basolateral (AP-BL) permeability at pH 5 [14.5 (+/-1.8) x 10(-6) cm/s] was 2-fold higher than at pH 7.5 [7.24 (+/-0.27) x 10(-6) cm/s]. Neutral and ionized dexloxiglumide species displayed permeabilities of 30.8 (+/-8.4) x 10(-6) cm/s and 9.03 (+/-1.31) x 10(-6) cm/s, respectively. The transport of dexloxiglumide across MDR1-MDCK (P-gp overexpressing Madine Darby canine kidney cells) monolayers was polarized, with a BL-AP/AP-BL permeability ratio of 9.35 (+/-0.73), which was reduced to 1.03 (+/-0.03) by P-gp inhibition. Rhodamine 123 efflux was reduced by dexloxiglumide from 4.06 (+/-0.34) to 2.84 (+/-0.15) across Caco-2 monolayers, and from 17.3 (+/-0.9) to 8.26 (+/-1.38) across MDR1-MDCK monolayers, further indicating dexloxiglumide interaction with P-gp. Additionally, P-gp ATPase activity increased with dexloxiglumide concentration. Dexloxiglumide was effluxed from MRP1-NIH3T3 cells (NIH-3T3 cells expressing the multidrug resistance-associated protein 1). Dexloxiglumide increased MRP1-substrate fluorescein uptake 4-fold, and fluorescein increased dexloxiglumide uptake 1.8-fold. Overall, in vitro transport studies indicate dexloxiglumide to be moderately soluble and moderately permeable, which is in agreement with the incomplete oral absorption of dexloxiglumide. In vitro, dexloxiglumide was moderately modulated by P-gp and MRP1, which provides a rationale for the design of drug interaction studies.

Fragrance material review on linalyl isovalerate.

A toxicologic and dermatologic review of linalyl isovalerate when used as a fragrance ingredient is presented.

Glutathione conjugation of the alpha-bromoisovaleric acid enantiomers in the rat in vivo and its stereoselectivity. Pharmacokinetics of biliary and urinary excretion of the glutathione conjugate and the mercapturate.

The glutathione (GSH) conjugation of (R)-and (S)-alpha-bromoisovaleric acid (BI) in the rat in vivo, and its stereoselectivity, have been characterized. After administration of racemic [1-14C]BI two radioactive metabolites were found in bile: only one of the possible diastereomeric BI-GSH conjugates, (R)-I-S-G (35 +/- 2% of the dose), and an unidentified metabolite "X" (6 +/- 1%). In urine, only one of the possible BI-mercapturates, (R)-I-S-MA (14 +/- 1%), minor unidentified polar metabolites (5 +/- 1%) and unchanged BI (13 +/- 2%) were excreted. When (R) or (S)-BI were administered separately, the same metabolites were found. However, a ten-fold difference in excretion half lives of the biliary metabolites was observed following (S)-and (R)-BI administration, (S)-BI being more rapidly excreted. The excretion of the mercapturate in urine shows the same difference in excretion rate: its half life after administration of (R)-BI was more than 10 times longer than after a dose of (S)-BI. More of the dose of (S)-BI was excreted after 5 hr in bile and urine: 58% and 23% respectively for (S)- and (R)-BI. Therefore, a pronounced stereoselectivity in GSH conjugation exists for the (R) and (S) enantiomers of BI in the rat in vivo, which is a major determinant of their pharmacokinetics. The results suggest that (slow) inversion of the chiral centre of BI occurred in the rat in vivo.