Cuyue Tang - Academia.edu (original) (raw)
Papers by Cuyue Tang
SET domain-containing protein 2 (SETD2), a histone methyltransferase, has been identified as a ta... more SET domain-containing protein 2 (SETD2), a histone methyltransferase, has been identified as a target of interest in certain hematological malignancies, including multiple myeloma. This account details the discovery of EPZ-719, a novel and potent SETD2 inhibitor with a high selectivity over other histone methyltransferases. A screening campaign of the Epizyme proprietary histone methyltransferase-biased library identified potential leads based on a 2-amidoindole core. Structure-based drug design (SBDD) and drug metabolism/pharmacokinetics (DMPK) optimization resulted in EPZ-719, an attractive tool compound for the interrogation of SETD2 biology that enables in vivo target validation studies.
Drug Metabolism and Disposition, 2004
In vitro studies were performed to identify the human cytochrome P450 enzyme(s) involved in the h... more In vitro studies were performed to identify the human cytochrome P450 enzyme(s) involved in the hydroxylation (isopropyl moiety) of a previously reported endothelin ET A receptor antagonist, compound A [(؉)-(5S,6R,7R)-2-isopropylamino-7-{4-methoxy-2-[(2R)-3-methoxy-2-methylpropyl]}-5-(3,4-methylenedioxyphenyl)cyclopenteno(1,2-b) pyridine 6-carboxylic acid]. Several lines of evidence indicated that the reaction was mainly catalyzed by CYP2C8. Of the 10 recombinant cytochrome P450 isoforms tested, only CYP2C8 exhibited hydroxylase activity. In agreement, inhibitory antibodies selective for CYP2C8 attenuated (>95%) the hydroxylase activity in human liver microsomes, whereas antibodies and chemical inhibitors selective for other cytochrome P450 iso-forms had a minor or no effect on the reaction. In addition, the formation of the hydroxy metabolite correlated well with CYP2C8selective paclitaxel 6␣-hydroxylation (r 2 ϳ0.92; p < 0.0001) and amodiaquine N-de-ethylation (r 2 ϳ0.91; p < 0.0001) in a bank of human liver microsomes (n ؍ 15 organ donors). Finally, compound A hydroxylase activity conformed to Michaelis-Menten kinetics, and the K m (Michaelis constant) in human liver microsomes was similar to that of CYP2C8 (ϳ10 M). It is concluded that the hydroxylation of compound A is mainly catalyzed by CYP2C8, and thus the reaction can possibly serve as an alternative marker assay for CYP2C8 in human liver microsomes.
Biochemical Pharmacology, 2007
Cytochrome P450 2C9 (CYP2C9) accounts for approximately 18% of the CYP protein content in human l... more Cytochrome P450 2C9 (CYP2C9) accounts for approximately 18% of the CYP protein content in human liver microsomes and catalyzes approximately 20% of the CYP-mediated metabolic reactions of drugs currently on the market [1,2]. It is also genetically polymorphic with a number of variants showing reduced catalytic activity [3]. As a result, drug interactions associated with CYP2C9 and altered pharmacokinetics in CYP2C9 polymorphic subjects have been an important theme in both academic fields and the pharmaceutical industry. It is well known that the success of these two b i o c h e m i c a l p h a r m a c o l o g y 7 3
Alzheimer's Research & Therapy, 2016
Background Familial Alzheimer’s disease (FAD) is caused by mutations in the amyloid precursor pro... more Background Familial Alzheimer’s disease (FAD) is caused by mutations in the amyloid precursor protein (APP) or presenilin (PS). Most PS mutations, which account for the majority of FAD cases, lead to an increased ratio of longer to shorter forms of the amyloid beta (Aβ) peptide. The therapeutic rationale of γ-secretase modulators (GSMs) for Alzheimer’s disease is based on this genetic evidence as well as on enzyme kinetics measurements showing changes in the processivity of the γ-secretase complex. This analysis suggests that GSMs could potentially offset some of the effects of PS mutations on APP processing, thereby addressing the root cause of early onset FAD. Unfortunately, the field has generated few, if any, molecules with good central nervous system (CNS) drug-like properties to enable proof-of-mechanism studies. Method We characterized the novel GSM FRM-36143 using multiple cellular assays to determine its in vitro potency and off-target activity as well as its potential to r...
ACS Medicinal Chemistry Letters, 2016
Investigation of a novel amino-aza-benzimidazolone structural class of positive allosteric modula... more Investigation of a novel amino-aza-benzimidazolone structural class of positive allosteric modulators (PAMs) of metabotropic glutamate receptor 2 (mGluR2) identified [2.2.2]-bicyclic amine 12 as an intriguing lead structure due to its promising physicochemical properties and lipophilic ligand efficiency (LLE). Further optimization led to chiral amide 18, which exhibited strong in vitro activity and attractive pharmacokinetic (PK) properties. Hypothesis-driven target design identified compound 21 as a potent, highly selective, orally bioavailable mGluR2 PAM, which addressed a CYP time-dependent inhibition (TDI) liability of 18, while maintaining excellent drug-like properties with robust in vivo activity in a clinically validated model of antipsychotic potential.
Pharmaceutical Research, 2011
To systemically investigate, for a therapeutic protein with a circulating soluble target, how the... more To systemically investigate, for a therapeutic protein with a circulating soluble target, how the interplay of target dynamics and drug pharmacokinetics defines the &amp;amp;amp;#39;total&amp;amp;amp;#39; and &amp;amp;amp;#39;free&amp;amp;amp;#39; drug and target temporal profiles. By extending the established rapid-binding target-mediated drug disposition (TMDD) pharmacokinetic model to circulating soluble targets, the temporal profiles of &amp;amp;amp;#39;total&amp;amp;amp;#39; and &amp;amp;amp;#39;free&amp;amp;amp;#39; drug and target were simulated with varying binding affinity (K(D)), target baseline (R(ss)), target turnover, and drug dose level. Two sets of published experimental data were compared with the simulated results. Binding to a circulating soluble target could lead to a divergence of the &amp;amp;amp;#39;free&amp;amp;amp;#39; drug from the &amp;amp;amp;#39;total&amp;amp;amp;#39; drug. Simulations show this divergent magnitude determined by K(D) and R(ss), with the temporal profile being defined by target turnover and drug dose level. As divergence proceeds, starting at the distribution phase, &amp;amp;amp;#39;free&amp;amp;amp;#39; drug would decline faster but eventually parallel &amp;amp;amp;#39;total&amp;amp;amp;#39; drug at the terminal phase, giving rise to a steeper distribution phase and comparable terminal half-life, relative to the &amp;amp;amp;#39;total&amp;amp;amp;#39; form. The model also allows for estimation of the dynamic change of &amp;amp;amp;#39;total&amp;amp;amp;#39; and &amp;amp;amp;#39;free&amp;amp;amp;#39; target in response to the treatment of a therapeutic protein drug, facilitating dose level and regimen design to achieve desired &amp;amp;amp;#39;free&amp;amp;amp;#39; target suppression. Model predictions compared favorably with two sets of published experimental data. Theoretical analyses identified key variables governing the different temporal profiles of &amp;amp;amp;#39;total&amp;amp;amp;#39; and &amp;amp;amp;#39;free&amp;amp;amp;#39; drug and target. The rapid-binding TMDD model reasonably captured the features of the interplay of drug pharmacokinetics and target dynamics for two reported cases.
Drug metabolism and disposition: the biological fate of chemicals
To study enantioselective aspects of the disposition of stiripentol (STP), a chiral allylic alcoh... more To study enantioselective aspects of the disposition of stiripentol (STP), a chiral allylic alcohol undergoing development as an antiepileptic drug, a stereoselective synthesis was developed and the configuration of the two enantiomers determined to be (R)-(+) and (S)-(-). Following a single oral dose (300 mg kg-1) of the individual enantiomers to adult male Sprague-Dawley rats, it was found that (R)-STP was transformed extensively to its antipode, whereas little inversion was detected when (S)-STP was administered. Studies on the mechanism of this apparently unidirectional chiral inversion revealed that the phenomenon was dependent on the presence of the side-chain C==C double bond, because the enantiomers of the corresponding saturated alcohol (D2602) did not interconvert in vivo. Experiments with analogs of STP labeled with deuterium or oxygen-18 at the chiral center showed that, whereas the deuterium was retained in vivo, partial loss of the 18O occurred from both enantiomers of...
Biochemical pharmacology, Jan 15, 2014
Two investigational compounds (FRM-1, (R)-7-fluoro-N-(quinuclidin-3-yl)benzo[b]thiophene-2-carbox... more Two investigational compounds (FRM-1, (R)-7-fluoro-N-(quinuclidin-3-yl)benzo[b]thiophene-2-carboxamide and FRM-2, (R)-7-cyano-N-(quinuclidin-3-yl)benzo[b]thiophene-2-carboxamide) resided in rat brain longer than in systemic circulation. In Caco-2 directional transport studies, they both showed good intrinsic passive permeability but differed significantly in efflux susceptibility (efflux ratio of <2 and ∼7, respectively), largely attributed to P-glycoprotein (P-gp). Capitalizing on these interesting properties, we investigated how cerebrospinal fluid (CSF) concentration (CCSF) would be shaped by unbound plasma concentration (Cu,p) and unbound brain concentration (Cu,b) in disequilibrium conditions and at steady state. Following subcutaneous administration, FRM-1CCSF largely followed Cu,p initially and leveled between Cu,p and Cu,b. However, it gradually approached Cu,b and became lower than, but parallel to Cu,b at the terminal phase. In contrast, FRM-2CCSF temporal profile mostl...
Pharmaceutical Research, 2004
Purpose. In this study, P-glycoprotein (P-gp) mediated efflux of simvastatin (SV), simvastatin ac... more Purpose. In this study, P-glycoprotein (P-gp) mediated efflux of simvastatin (SV), simvastatin acid (SVA), and atorvastatin (AVA) and inhibition of P-gp by SV, SVA, and AVA were evaluated to assess the role of P-gp in drug interactions. Methods. P-gp mediated efflux of SV, SVA, and AVA was determined by directional transport across monolayers of LLC-PK1 cells and LLC-PK1 cells transfected with human MDR1. Inhibition of P-gp was evaluated by studying the vinblastine efflux in Caco-2 cells and in P-gp overexpressing KBV1 cells at concentrations of SV, SVA, and AVA up to 50 M. Results. Directional transport studies showed insignificant P-gp mediated efflux of SV, and moderate P-gp transport [2.4-3.8 and 3.0-6.4 higher Basolateral (B) to Apical (A) than A to B transport] for SVA and AVA, respectively. Inhibition studies did not show the same trend as the transport studies with SV and AVA inhibiting P-gp (IC 50 ∼25-50 M) but SVA not showing any inhibition of P-gp. Conclusions. The moderate level of P-gp mediated transport and low affinity of SV, SVA, and AVA for P-gp inhibition compared to systemic drug levels suggest that drug interactions due to competition for P-gp transport is unlikely to be a significant factor in adverse drug interactions. Moreover, the inconsistencies between P-gp inhibition studies and P-gp transport of SV, SVA, and AVA indicate that the inhibition studies are not a valid means to identify statins as Pgp substrates.
Journal of Medicinal Chemistry, 2008
Journal of Medicinal Chemistry, 2004
Bradykinin B1 receptor antagonists embody a potentially novel approach for the treatment of chron... more Bradykinin B1 receptor antagonists embody a potentially novel approach for the treatment of chronic pain and inflammation. A series of 2,3-diaminopyridine B1 antagonists was optimized to have sub-nanomolar affinity and good pharmacokinetic properties. Lead compounds were shown to exhibit good efficacy in rabbit in vivo models of pain and inflammation.
Journal of Medicinal Chemistry, 2007
A series of biphenylaminocyclopropane carboxamide based bradykinin B1 receptor antagonists has be... more A series of biphenylaminocyclopropane carboxamide based bradykinin B1 receptor antagonists has been developed that possesses good pharmacokinetic properties and is CNS penetrant. Discovery that the replacement of the trifluoropropionamide in the lead structure with polyhaloacetamides, particularly a trifluoroacetamide, significantly reduced P-glycoprotein mediated efflux for the series proved essential. One of these novel bradykinin B1 antagonists (13b) also exhibited suitable pharmacokinetic properties and efficient ex vivo receptor occupancy for further development as a novel approach for the treatment of pain and inflammation.
Journal of Medicinal Chemistry, 2008
Journal of Clinical Investigation, 2009
The epidemics of obesity and metabolic disorders have well-recognized health and economic burdens... more The epidemics of obesity and metabolic disorders have well-recognized health and economic burdens. Pharmacologic treatments for these diseases remain unsatisfactory with respect to both efficacy and side-effect profiles. Here, we have identified a potential central role for T-type calcium channels in regulating body weight maintenance and sleep. Previously, it was shown that mice lacking Ca V 3.1 T-type calcium channels have altered sleep/wake activity. We found that these mice were also resistant to high-fat diet-induced weight gain, without changes in food intake or sensitivity to high-fat diet-induced disruptions of diurnal rhythm. Administration of a potent and selective antagonist of T-type calcium channels, TTA-A2, to normal-weight animals prior to the inactive phase acutely increased sleep, decreased body core temperature, and prevented high-fat diet-induced weight gain. Administration of TTA-A2 to obese rodents reduced body weight and fat mass while concurrently increasing lean muscle mass. These effects likely result from better alignment of diurnal feeding patterns with daily changes in circadian physiology and potentially an increased metabolic rate during the active phase. Together, these studies reveal what we believe to be a previously unknown role for T-type calcium channels in the regulation of sleep and weight maintenance and suggest the potential for a novel therapeutic approach to treating obesity. Conflict of interest: This work has been funded by Merck Research Laboratories. The authors are employees of Merck & Co. Inc. and potentially own stock and/or hold stock options in the company.
Drug Metabolism and Disposition, 2013
In vitro assessment of drug-drug interaction potential of boceprevir associated with drug metabol... more In vitro assessment of drug-drug interaction potential of boceprevir associated with drug metabolizing enzymes and transporters
Drug Metabolism and Disposition, 2006
plasma concentration-time curve; C max , peak plasma concentration; CL, plasma clearance; F h , h... more plasma concentration-time curve; C max , peak plasma concentration; CL, plasma clearance; F h , hepatic availability; V dss , volume of distribution at steady-state; t 1/2 , half-life; i.pv., intra-hepatic portal vein; i.v., intravenous; IS, internal standard; LC-MS/MS, liquid chromatography coupled with tandem mass spectrometry.
Computational Biology and Chemistry, 2013
Protein phosphorylation and O-GlcNAcylation are reciprocally regulated. As hyperphosphorylation i... more Protein phosphorylation and O-GlcNAcylation are reciprocally regulated. As hyperphosphorylation is implicated in tau pathology, approaches have been exploited to reduce the magnitude of tau phosphorylation by increasing the level of tau O-GlcNAcylation. With mathematic models constructed to describe different kinetic scenarios, we analyzed the temporal change of an O-GlcNAcylated protein in contrast to that of the phosphorylated form upon inhibition of O-GlcNAcase (OGA). The analyses indicate that when degradation of the modified protein is negligible relative to the naked one, the magnitude of O-GlcNAcylated protein increase is proportional to the level of inhibition, while the extent of phosphorylated protein decline varies due to other factors. Furthermore, the increase of O-GlcNAcylated protein parallels with the decrease of phosphorylated form upon acute or short-term inhibition of OGA, as observed in many in vitro and short term in vivo studies. However, phosphorylated protein is predicted to return to its initial level while O-GlcNAcylated protein to achieve a higher steady level under sustained inhibition. This simulated result is in line with a recent report on long-term inhibition of OGA in transgenic mice. Noticeably, inhibition withdrawal is anticipated to cause a transient rise of phosphorylated protein. If degradation of modified proteins proceeds in addition to the naked one, the characteristic temporal profiles of each form in response to OGA inhibition would depend on the relative importance of individual degradation pathways. The models described herein may serve as a useful investigational tool that will provide insight into pharmacological intervention for tauopathies in particular and for reciprocally modulated reactions in general.
Chemical Research in Toxicology, 1999
Tolbutamide (TOLB), a widely used hypoglycemic agent in the therapy of non-insulin-dependent diab... more Tolbutamide (TOLB), a widely used hypoglycemic agent in the therapy of non-insulin-dependent diabetes mellitus, has been reported to be teratogenic and/or embryotoxic in several animal species and humans. It has been proposed that the teratogenic effects of TOLB are linked to drug-mediated depletion of glutathione (GSH) through inhibition of the enzyme glutathione reductase (GR), although the mechanism by which this inhibition occurs remains unknown. In the study presented here, rats were injected with TOLB (200 mg/kg ip), and bile was collected for analysis by liquid chromatography/tandem mass spectrometry (LC/MS/MS). This led to the identification of S-(n-butylcarbamoyl)glutathione (SBuG), a reactive GSH conjugate derived from n-butyl isocyanate, as a minor metabolite of TOLB in bile. Upon incubation of SBuG (0.25-1.0 mM) with GR from either yeast or bovine intestinal mucosa in the presence of NADPH (0.20 mM), enzyme activity was lost in a time- and concentration-dependent manner. No inhibition was observed when NADPH was omitted from incubations, or when the natural substrate for the enzyme, glutathione disulfide (GSSG, 0.05 mM), was added. TOLB itself did not inhibit GR over the concentration range of 0.8-2.0 mM. It is concluded that metabolic activation of TOLB in vivo leads to the generation of reactive intermediates (n-butyl isocyanate and SBuG) which carbamoylate and thereby inhibit GR. At critical periods of organogenesis, the resulting perturbation of GSH homeostasis in exposed tissues may play a key role in the teratogenic and/or embryotoxic effects of TOLB.
Chemical Research in Toxicology, 2005
Bioorganic & Medicinal Chemistry Letters, 2006
A series of 2,3-diaminopyridine bradykinin B(1) antagonists was modified to mitigate the potentia... more A series of 2,3-diaminopyridine bradykinin B(1) antagonists was modified to mitigate the potential for bioactivation. Removal of the 3-amino group and incorporation of basic 5-piperazinyl carboxamides at the pyridine 5-position provided compounds with high affinity for the human B(1) receptor.
SET domain-containing protein 2 (SETD2), a histone methyltransferase, has been identified as a ta... more SET domain-containing protein 2 (SETD2), a histone methyltransferase, has been identified as a target of interest in certain hematological malignancies, including multiple myeloma. This account details the discovery of EPZ-719, a novel and potent SETD2 inhibitor with a high selectivity over other histone methyltransferases. A screening campaign of the Epizyme proprietary histone methyltransferase-biased library identified potential leads based on a 2-amidoindole core. Structure-based drug design (SBDD) and drug metabolism/pharmacokinetics (DMPK) optimization resulted in EPZ-719, an attractive tool compound for the interrogation of SETD2 biology that enables in vivo target validation studies.
Drug Metabolism and Disposition, 2004
In vitro studies were performed to identify the human cytochrome P450 enzyme(s) involved in the h... more In vitro studies were performed to identify the human cytochrome P450 enzyme(s) involved in the hydroxylation (isopropyl moiety) of a previously reported endothelin ET A receptor antagonist, compound A [(؉)-(5S,6R,7R)-2-isopropylamino-7-{4-methoxy-2-[(2R)-3-methoxy-2-methylpropyl]}-5-(3,4-methylenedioxyphenyl)cyclopenteno(1,2-b) pyridine 6-carboxylic acid]. Several lines of evidence indicated that the reaction was mainly catalyzed by CYP2C8. Of the 10 recombinant cytochrome P450 isoforms tested, only CYP2C8 exhibited hydroxylase activity. In agreement, inhibitory antibodies selective for CYP2C8 attenuated (>95%) the hydroxylase activity in human liver microsomes, whereas antibodies and chemical inhibitors selective for other cytochrome P450 iso-forms had a minor or no effect on the reaction. In addition, the formation of the hydroxy metabolite correlated well with CYP2C8selective paclitaxel 6␣-hydroxylation (r 2 ϳ0.92; p < 0.0001) and amodiaquine N-de-ethylation (r 2 ϳ0.91; p < 0.0001) in a bank of human liver microsomes (n ؍ 15 organ donors). Finally, compound A hydroxylase activity conformed to Michaelis-Menten kinetics, and the K m (Michaelis constant) in human liver microsomes was similar to that of CYP2C8 (ϳ10 M). It is concluded that the hydroxylation of compound A is mainly catalyzed by CYP2C8, and thus the reaction can possibly serve as an alternative marker assay for CYP2C8 in human liver microsomes.
Biochemical Pharmacology, 2007
Cytochrome P450 2C9 (CYP2C9) accounts for approximately 18% of the CYP protein content in human l... more Cytochrome P450 2C9 (CYP2C9) accounts for approximately 18% of the CYP protein content in human liver microsomes and catalyzes approximately 20% of the CYP-mediated metabolic reactions of drugs currently on the market [1,2]. It is also genetically polymorphic with a number of variants showing reduced catalytic activity [3]. As a result, drug interactions associated with CYP2C9 and altered pharmacokinetics in CYP2C9 polymorphic subjects have been an important theme in both academic fields and the pharmaceutical industry. It is well known that the success of these two b i o c h e m i c a l p h a r m a c o l o g y 7 3
Alzheimer's Research & Therapy, 2016
Background Familial Alzheimer’s disease (FAD) is caused by mutations in the amyloid precursor pro... more Background Familial Alzheimer’s disease (FAD) is caused by mutations in the amyloid precursor protein (APP) or presenilin (PS). Most PS mutations, which account for the majority of FAD cases, lead to an increased ratio of longer to shorter forms of the amyloid beta (Aβ) peptide. The therapeutic rationale of γ-secretase modulators (GSMs) for Alzheimer’s disease is based on this genetic evidence as well as on enzyme kinetics measurements showing changes in the processivity of the γ-secretase complex. This analysis suggests that GSMs could potentially offset some of the effects of PS mutations on APP processing, thereby addressing the root cause of early onset FAD. Unfortunately, the field has generated few, if any, molecules with good central nervous system (CNS) drug-like properties to enable proof-of-mechanism studies. Method We characterized the novel GSM FRM-36143 using multiple cellular assays to determine its in vitro potency and off-target activity as well as its potential to r...
ACS Medicinal Chemistry Letters, 2016
Investigation of a novel amino-aza-benzimidazolone structural class of positive allosteric modula... more Investigation of a novel amino-aza-benzimidazolone structural class of positive allosteric modulators (PAMs) of metabotropic glutamate receptor 2 (mGluR2) identified [2.2.2]-bicyclic amine 12 as an intriguing lead structure due to its promising physicochemical properties and lipophilic ligand efficiency (LLE). Further optimization led to chiral amide 18, which exhibited strong in vitro activity and attractive pharmacokinetic (PK) properties. Hypothesis-driven target design identified compound 21 as a potent, highly selective, orally bioavailable mGluR2 PAM, which addressed a CYP time-dependent inhibition (TDI) liability of 18, while maintaining excellent drug-like properties with robust in vivo activity in a clinically validated model of antipsychotic potential.
Pharmaceutical Research, 2011
To systemically investigate, for a therapeutic protein with a circulating soluble target, how the... more To systemically investigate, for a therapeutic protein with a circulating soluble target, how the interplay of target dynamics and drug pharmacokinetics defines the &amp;amp;amp;#39;total&amp;amp;amp;#39; and &amp;amp;amp;#39;free&amp;amp;amp;#39; drug and target temporal profiles. By extending the established rapid-binding target-mediated drug disposition (TMDD) pharmacokinetic model to circulating soluble targets, the temporal profiles of &amp;amp;amp;#39;total&amp;amp;amp;#39; and &amp;amp;amp;#39;free&amp;amp;amp;#39; drug and target were simulated with varying binding affinity (K(D)), target baseline (R(ss)), target turnover, and drug dose level. Two sets of published experimental data were compared with the simulated results. Binding to a circulating soluble target could lead to a divergence of the &amp;amp;amp;#39;free&amp;amp;amp;#39; drug from the &amp;amp;amp;#39;total&amp;amp;amp;#39; drug. Simulations show this divergent magnitude determined by K(D) and R(ss), with the temporal profile being defined by target turnover and drug dose level. As divergence proceeds, starting at the distribution phase, &amp;amp;amp;#39;free&amp;amp;amp;#39; drug would decline faster but eventually parallel &amp;amp;amp;#39;total&amp;amp;amp;#39; drug at the terminal phase, giving rise to a steeper distribution phase and comparable terminal half-life, relative to the &amp;amp;amp;#39;total&amp;amp;amp;#39; form. The model also allows for estimation of the dynamic change of &amp;amp;amp;#39;total&amp;amp;amp;#39; and &amp;amp;amp;#39;free&amp;amp;amp;#39; target in response to the treatment of a therapeutic protein drug, facilitating dose level and regimen design to achieve desired &amp;amp;amp;#39;free&amp;amp;amp;#39; target suppression. Model predictions compared favorably with two sets of published experimental data. Theoretical analyses identified key variables governing the different temporal profiles of &amp;amp;amp;#39;total&amp;amp;amp;#39; and &amp;amp;amp;#39;free&amp;amp;amp;#39; drug and target. The rapid-binding TMDD model reasonably captured the features of the interplay of drug pharmacokinetics and target dynamics for two reported cases.
Drug metabolism and disposition: the biological fate of chemicals
To study enantioselective aspects of the disposition of stiripentol (STP), a chiral allylic alcoh... more To study enantioselective aspects of the disposition of stiripentol (STP), a chiral allylic alcohol undergoing development as an antiepileptic drug, a stereoselective synthesis was developed and the configuration of the two enantiomers determined to be (R)-(+) and (S)-(-). Following a single oral dose (300 mg kg-1) of the individual enantiomers to adult male Sprague-Dawley rats, it was found that (R)-STP was transformed extensively to its antipode, whereas little inversion was detected when (S)-STP was administered. Studies on the mechanism of this apparently unidirectional chiral inversion revealed that the phenomenon was dependent on the presence of the side-chain C==C double bond, because the enantiomers of the corresponding saturated alcohol (D2602) did not interconvert in vivo. Experiments with analogs of STP labeled with deuterium or oxygen-18 at the chiral center showed that, whereas the deuterium was retained in vivo, partial loss of the 18O occurred from both enantiomers of...
Biochemical pharmacology, Jan 15, 2014
Two investigational compounds (FRM-1, (R)-7-fluoro-N-(quinuclidin-3-yl)benzo[b]thiophene-2-carbox... more Two investigational compounds (FRM-1, (R)-7-fluoro-N-(quinuclidin-3-yl)benzo[b]thiophene-2-carboxamide and FRM-2, (R)-7-cyano-N-(quinuclidin-3-yl)benzo[b]thiophene-2-carboxamide) resided in rat brain longer than in systemic circulation. In Caco-2 directional transport studies, they both showed good intrinsic passive permeability but differed significantly in efflux susceptibility (efflux ratio of <2 and ∼7, respectively), largely attributed to P-glycoprotein (P-gp). Capitalizing on these interesting properties, we investigated how cerebrospinal fluid (CSF) concentration (CCSF) would be shaped by unbound plasma concentration (Cu,p) and unbound brain concentration (Cu,b) in disequilibrium conditions and at steady state. Following subcutaneous administration, FRM-1CCSF largely followed Cu,p initially and leveled between Cu,p and Cu,b. However, it gradually approached Cu,b and became lower than, but parallel to Cu,b at the terminal phase. In contrast, FRM-2CCSF temporal profile mostl...
Pharmaceutical Research, 2004
Purpose. In this study, P-glycoprotein (P-gp) mediated efflux of simvastatin (SV), simvastatin ac... more Purpose. In this study, P-glycoprotein (P-gp) mediated efflux of simvastatin (SV), simvastatin acid (SVA), and atorvastatin (AVA) and inhibition of P-gp by SV, SVA, and AVA were evaluated to assess the role of P-gp in drug interactions. Methods. P-gp mediated efflux of SV, SVA, and AVA was determined by directional transport across monolayers of LLC-PK1 cells and LLC-PK1 cells transfected with human MDR1. Inhibition of P-gp was evaluated by studying the vinblastine efflux in Caco-2 cells and in P-gp overexpressing KBV1 cells at concentrations of SV, SVA, and AVA up to 50 M. Results. Directional transport studies showed insignificant P-gp mediated efflux of SV, and moderate P-gp transport [2.4-3.8 and 3.0-6.4 higher Basolateral (B) to Apical (A) than A to B transport] for SVA and AVA, respectively. Inhibition studies did not show the same trend as the transport studies with SV and AVA inhibiting P-gp (IC 50 ∼25-50 M) but SVA not showing any inhibition of P-gp. Conclusions. The moderate level of P-gp mediated transport and low affinity of SV, SVA, and AVA for P-gp inhibition compared to systemic drug levels suggest that drug interactions due to competition for P-gp transport is unlikely to be a significant factor in adverse drug interactions. Moreover, the inconsistencies between P-gp inhibition studies and P-gp transport of SV, SVA, and AVA indicate that the inhibition studies are not a valid means to identify statins as Pgp substrates.
Journal of Medicinal Chemistry, 2008
Journal of Medicinal Chemistry, 2004
Bradykinin B1 receptor antagonists embody a potentially novel approach for the treatment of chron... more Bradykinin B1 receptor antagonists embody a potentially novel approach for the treatment of chronic pain and inflammation. A series of 2,3-diaminopyridine B1 antagonists was optimized to have sub-nanomolar affinity and good pharmacokinetic properties. Lead compounds were shown to exhibit good efficacy in rabbit in vivo models of pain and inflammation.
Journal of Medicinal Chemistry, 2007
A series of biphenylaminocyclopropane carboxamide based bradykinin B1 receptor antagonists has be... more A series of biphenylaminocyclopropane carboxamide based bradykinin B1 receptor antagonists has been developed that possesses good pharmacokinetic properties and is CNS penetrant. Discovery that the replacement of the trifluoropropionamide in the lead structure with polyhaloacetamides, particularly a trifluoroacetamide, significantly reduced P-glycoprotein mediated efflux for the series proved essential. One of these novel bradykinin B1 antagonists (13b) also exhibited suitable pharmacokinetic properties and efficient ex vivo receptor occupancy for further development as a novel approach for the treatment of pain and inflammation.
Journal of Medicinal Chemistry, 2008
Journal of Clinical Investigation, 2009
The epidemics of obesity and metabolic disorders have well-recognized health and economic burdens... more The epidemics of obesity and metabolic disorders have well-recognized health and economic burdens. Pharmacologic treatments for these diseases remain unsatisfactory with respect to both efficacy and side-effect profiles. Here, we have identified a potential central role for T-type calcium channels in regulating body weight maintenance and sleep. Previously, it was shown that mice lacking Ca V 3.1 T-type calcium channels have altered sleep/wake activity. We found that these mice were also resistant to high-fat diet-induced weight gain, without changes in food intake or sensitivity to high-fat diet-induced disruptions of diurnal rhythm. Administration of a potent and selective antagonist of T-type calcium channels, TTA-A2, to normal-weight animals prior to the inactive phase acutely increased sleep, decreased body core temperature, and prevented high-fat diet-induced weight gain. Administration of TTA-A2 to obese rodents reduced body weight and fat mass while concurrently increasing lean muscle mass. These effects likely result from better alignment of diurnal feeding patterns with daily changes in circadian physiology and potentially an increased metabolic rate during the active phase. Together, these studies reveal what we believe to be a previously unknown role for T-type calcium channels in the regulation of sleep and weight maintenance and suggest the potential for a novel therapeutic approach to treating obesity. Conflict of interest: This work has been funded by Merck Research Laboratories. The authors are employees of Merck & Co. Inc. and potentially own stock and/or hold stock options in the company.
Drug Metabolism and Disposition, 2013
In vitro assessment of drug-drug interaction potential of boceprevir associated with drug metabol... more In vitro assessment of drug-drug interaction potential of boceprevir associated with drug metabolizing enzymes and transporters
Drug Metabolism and Disposition, 2006
plasma concentration-time curve; C max , peak plasma concentration; CL, plasma clearance; F h , h... more plasma concentration-time curve; C max , peak plasma concentration; CL, plasma clearance; F h , hepatic availability; V dss , volume of distribution at steady-state; t 1/2 , half-life; i.pv., intra-hepatic portal vein; i.v., intravenous; IS, internal standard; LC-MS/MS, liquid chromatography coupled with tandem mass spectrometry.
Computational Biology and Chemistry, 2013
Protein phosphorylation and O-GlcNAcylation are reciprocally regulated. As hyperphosphorylation i... more Protein phosphorylation and O-GlcNAcylation are reciprocally regulated. As hyperphosphorylation is implicated in tau pathology, approaches have been exploited to reduce the magnitude of tau phosphorylation by increasing the level of tau O-GlcNAcylation. With mathematic models constructed to describe different kinetic scenarios, we analyzed the temporal change of an O-GlcNAcylated protein in contrast to that of the phosphorylated form upon inhibition of O-GlcNAcase (OGA). The analyses indicate that when degradation of the modified protein is negligible relative to the naked one, the magnitude of O-GlcNAcylated protein increase is proportional to the level of inhibition, while the extent of phosphorylated protein decline varies due to other factors. Furthermore, the increase of O-GlcNAcylated protein parallels with the decrease of phosphorylated form upon acute or short-term inhibition of OGA, as observed in many in vitro and short term in vivo studies. However, phosphorylated protein is predicted to return to its initial level while O-GlcNAcylated protein to achieve a higher steady level under sustained inhibition. This simulated result is in line with a recent report on long-term inhibition of OGA in transgenic mice. Noticeably, inhibition withdrawal is anticipated to cause a transient rise of phosphorylated protein. If degradation of modified proteins proceeds in addition to the naked one, the characteristic temporal profiles of each form in response to OGA inhibition would depend on the relative importance of individual degradation pathways. The models described herein may serve as a useful investigational tool that will provide insight into pharmacological intervention for tauopathies in particular and for reciprocally modulated reactions in general.
Chemical Research in Toxicology, 1999
Tolbutamide (TOLB), a widely used hypoglycemic agent in the therapy of non-insulin-dependent diab... more Tolbutamide (TOLB), a widely used hypoglycemic agent in the therapy of non-insulin-dependent diabetes mellitus, has been reported to be teratogenic and/or embryotoxic in several animal species and humans. It has been proposed that the teratogenic effects of TOLB are linked to drug-mediated depletion of glutathione (GSH) through inhibition of the enzyme glutathione reductase (GR), although the mechanism by which this inhibition occurs remains unknown. In the study presented here, rats were injected with TOLB (200 mg/kg ip), and bile was collected for analysis by liquid chromatography/tandem mass spectrometry (LC/MS/MS). This led to the identification of S-(n-butylcarbamoyl)glutathione (SBuG), a reactive GSH conjugate derived from n-butyl isocyanate, as a minor metabolite of TOLB in bile. Upon incubation of SBuG (0.25-1.0 mM) with GR from either yeast or bovine intestinal mucosa in the presence of NADPH (0.20 mM), enzyme activity was lost in a time- and concentration-dependent manner. No inhibition was observed when NADPH was omitted from incubations, or when the natural substrate for the enzyme, glutathione disulfide (GSSG, 0.05 mM), was added. TOLB itself did not inhibit GR over the concentration range of 0.8-2.0 mM. It is concluded that metabolic activation of TOLB in vivo leads to the generation of reactive intermediates (n-butyl isocyanate and SBuG) which carbamoylate and thereby inhibit GR. At critical periods of organogenesis, the resulting perturbation of GSH homeostasis in exposed tissues may play a key role in the teratogenic and/or embryotoxic effects of TOLB.
Chemical Research in Toxicology, 2005
Bioorganic & Medicinal Chemistry Letters, 2006
A series of 2,3-diaminopyridine bradykinin B(1) antagonists was modified to mitigate the potentia... more A series of 2,3-diaminopyridine bradykinin B(1) antagonists was modified to mitigate the potential for bioactivation. Removal of the 3-amino group and incorporation of basic 5-piperazinyl carboxamides at the pyridine 5-position provided compounds with high affinity for the human B(1) receptor.