ABSTRACT
A series of trisubstituted pyrimidines were synthesized to improve aqueous solubility of our first TRPV1 clinical candidate (1; AMG 517), while maintaining potent TRPV1 inhibitory activity. Structure-activity and structure-solubility studies led to the identification of compound 26. The aqueous solubility of 26 (>or=200microg/mL, 0.01 HCl; 6.7microg/mL, phosphate buffered saline (PBS); 150microg/mL, fasted-state simulated intestinal fluid (SIF)) was significantly improved over 1. In addition, compound 26 was found to be orally bioavailable (rat F(oral)=24%) and had potent TRPV1 antagonist activity (capsaicin IC(50)=1.5nM) comparable to that of 1.
Subject(s)
Pyrimidines/chemical synthesis , Pyrimidines/pharmacology , TRPV Cation Channels/antagonists & inhibitors , Animals , Benzothiazoles/chemistry , Benzothiazoles/pharmacology , CHO Cells , Capsaicin/antagonists & inhibitors , Cricetinae , Cricetulus , Drug Evaluation, Preclinical , Hydrogen-Ion Concentration , Piperazines/chemical synthesis , Piperazines/pharmacology , Pyrimidines/chemistry , Rats , Rats, Sprague-Dawley , Solubility/drug effects , Structure-Activity Relationship , TRPV Cation Channels/biosynthesis , TRPV Cation Channels/genetics , TRPV Cation Channels/physiologyABSTRACT
The vanilloid receptor-1 (VR1 or TRPV1) is a member of the transient receptor potential (TRP) family of ion channels and plays a role as an integrator of multiple pain-producing stimuli. From a high-throughput screening assay, measuring calcium uptake in TRPV1-expressing cells, we identified an N-aryl trans-cinnamide (AMG9810, compound 9) that acts as a potent TRPV1 antagonist. We have demonstrated the antihyperalgesic properties of 9 in vivo and have also reported the discovery of novel, orally bioavailable cinnamides derived from this lead. Herein, we expand our investigations and describe the synthesis and biological evaluation of a series of conformationally constrained analogues of the s-cis conformer of compound 9. These investigations resulted in the identification of 4-amino- and 4-oxopyrimidine cores as suitable isosteric replacements for the trans-acrylamide moiety. The best examples from this series, pyrimidines 79 and 74, were orally bioavailable and exhibited potent antagonism of both rat (IC50 = 4.5 and 0.6 nM, respectively) and human TRPV1 (IC50 = 7.4 and 3.7 nM, respectively). In addition, compound 74 was shown to be efficacious at blocking a TRPV1-mediated physiological response in vivo in the capsaicin-induced hypothermia model in rats; however, it was ineffective at preventing thermal hyperalgesia induced by complete Freund's adjuvant in rats.
Subject(s)
Aminoquinolines/chemical synthesis , Analgesics/chemical synthesis , Pyrimidines/chemical synthesis , Quinolines/chemical synthesis , TRPV Cation Channels/antagonists & inhibitors , Administration, Oral , Aminoquinolines/chemistry , Aminoquinolines/pharmacology , Analgesics/chemistry , Analgesics/pharmacology , Animals , Biological Availability , Body Temperature/drug effects , CHO Cells , Cricetinae , Cricetulus , Humans , Hyperalgesia/prevention & control , Injections, Intravenous , Male , Models, Molecular , Molecular Conformation , Pyrimidines/chemistry , Pyrimidines/pharmacology , Quinolines/chemistry , Quinolines/pharmacology , Rats , Rats, Sprague-Dawley , Stereoisomerism , Structure-Activity Relationship , ThermodynamicsABSTRACT
A series of novel 4-oxopyrimidine TRPV1 antagonists was evaluated in assays measuring the blockade of capsaicin or acid-induced influx of calcium into CHO cells expressing TRPV1. The investigation of the structure-activity relationships in the heterocyclic A-region revealed the optimum pharmacophoric elements required for activity in this series and resulted in the identification of subnanomolar TRPV1 antagonists. The most potent of these antagonists were thoroughly profiled in pharmacokinetic assays. Optimization of the heterocyclic A-region led to the design and synthesis of 23, a compound that potently blocked multiple modes of TRPV1 activation. Compound 23 was shown to be effective in a rodent "on-target" biochemical challenge model (capsaicin-induced flinch, ED50 = 0.33 mg/kg p.o.) and was antihyperalgesic in a model of inflammatory pain (CFA-induced thermal hyperalgesia, MED = 0.83 mg/kg, p.o.). Based on its in vivo efficacy and pharmacokinetic profile, compound 23 (N-{4-[6-(4-trifluoromethyl-phenyl)-pyrimidin-4-yloxy]-benzothiazol-2-yl}-acetamide; AMG 517) was selected for further evaluation in human clinical trials.
Subject(s)
Analgesics/chemical synthesis , Benzothiazoles/chemical synthesis , Pyrimidines/chemical synthesis , TRPV Cation Channels/antagonists & inhibitors , Analgesics/pharmacokinetics , Analgesics/pharmacology , Animals , Benzothiazoles/pharmacokinetics , Benzothiazoles/pharmacology , CHO Cells , Calcium/metabolism , Cricetinae , Cricetulus , Dogs , Drug Stability , Haplorhini , Humans , Hyperalgesia/drug therapy , In Vitro Techniques , Inflammation/drug therapy , Male , Microsomes, Liver/metabolism , Pain Measurement , Pyrimidines/pharmacokinetics , Pyrimidines/pharmacology , Rats , Rats, Sprague-Dawley , Solubility , Structure-Activity Relationship , TRPV Cation Channels/geneticsABSTRACT
The vanilloid receptor-1 (VR1 or TRPV1) is a membrane-bound, nonselective cation channel that is predominantly expressed by peripheral neurons sensing painful stimuli. TRPV1 antagonists produce antihyperalgesic effects in animal models of inflammatory and neuropathic pain. Herein, we describe the synthesis and the structure-activity relationships of a series of 2-(4-pyridin-2-ylpiperazin-1-yl)-1H-benzo[d]imidazoles as novel TRPV1 antagonists. Compound 46ad was among the most potent analogues in this series. This compound was orally bioavailable in rats and was efficacious in blocking capsaicin-induced flinch in rats in a dose-dependent manner. Compound 46ad also reversed thermal hyperalgesia in a model of inflammatory pain, which was induced by complete Freund's adjuvant (CFA).
Subject(s)
Analgesics/chemical synthesis , Benzimidazoles/chemical synthesis , Piperazines/chemical synthesis , TRPV Cation Channels/antagonists & inhibitors , Administration, Oral , Analgesics/chemistry , Analgesics/pharmacology , Animals , Benzimidazoles/chemistry , Benzimidazoles/pharmacology , Biological Availability , CHO Cells , Calcium/metabolism , Capsaicin/pharmacology , Cricetinae , Cricetulus , Freund's Adjuvant , Hot Temperature , Hydrogen-Ion Concentration , Hyperalgesia/chemically induced , Hyperalgesia/drug therapy , Male , Pain Measurement , Piperazines/chemistry , Piperazines/pharmacology , Rats , Rats, Sprague-Dawley , Recombinant Proteins/antagonists & inhibitors , Stereoisomerism , Structure-Activity RelationshipABSTRACT
The vanilloid receptor-1 (TRPV1 or VR1) is a member of the transient receptor potential (TRP) family of ion channels and plays a role in regulating the function of sensory nerves. A growing body of evidence demonstrates the therapeutic potential of TRPV1 modulators, particularly in the management of pain. As a result of our screening efforts, we identified (E)-3-(4-tert-butylphenyl)-N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)acrylamide (1), an antagonist that blocks the capsaicin-induced and pH-induced uptake of (45)Ca(2+) in TRPV1-expressing Chinese hamster ovary cells with IC(50) values of 17 +/- 5 and 150 +/- 80 nM, respectively. In this report, we describe the synthesis and structure-activity relationship of a series of N-aryl cinnamides, the most potent of which (49a and 49b) exhibit good oral bioavailability in rats (F(oral) = 39% and 17%, respectively).