ABSTRACT
The pharmacological profile of PF-00885706, a selective 5-HT(4) receptor partial agonist, was investigated. PF-00885706 displayed a high binding affinity for the human 5-HT(4d) receptor with a K(i) of 3.7 nM that translates to functional agonist activity in vitro with EC(50) values of 4.0 nM and 6.6 nM in cell-based assays of human recombinant 5-HT(4d) receptors and rat tunica muscularis mucosae tissues, respectively. In both assays, partial agonism was confirmed with E(max) values of 84% and 78%, respectively. Notably, PF-00885706 was highly selective, displaying >1000-fold higher affinity for 5-HT(4d) receptors compared to 5-HT(1A), 5-HT(1B), 5-HT(1D), 5-HT(2A), 5-HT(2B), 5-HT(2C), 5-HT(3), 5-HT(7), and D(2long) receptors. Furthermore, in vitro binding assays demonstrated that PF-00885706 had no biologically significant interaction with physiologically important enzymes, ion channels including hERG channel, or receptors at concentrations up to 10 microM except for binding to the sigma(2) receptor. PF-00885706 exhibited weak binding affinity for the sigma(2) receptor yielding a K(i) value of 3 microM, which is more than 800-fold weaker than that for the 5-HT(4d) receptor. Oral administration of PF-00885706 to dogs resulted in marked and long-lasting stimulation of gastric motility with a minimum effective dose of 0.001 mg/kg. Pharmacokinetic analysis revealed that PF-00885706 has a low to moderate volume of distribution and the complete absorption in dogs. Pharmacokinetic and pharmacodynamic analysis of PF-00885706 in the dog gastric motility model showed a correlation between plasma concentrations and enhancement of gastric motility. Thus, PF-00885706 is an orally active, highly selective partial agonist for 5-HT(4) receptors that is expected to be effective for the treatment with gastrointestinal dysmotility disorders with reduced adverse effects mediated by other related receptors.
Subject(s)
Benzimidazoles/pharmacology , Benzimidazoles/pharmacokinetics , Cyclobutanes/pharmacology , Cyclobutanes/pharmacokinetics , Piperidines/pharmacology , Piperidines/pharmacokinetics , Receptors, Serotonin, 5-HT4/metabolism , Serotonin 5-HT4 Receptor Agonists , Animals , Cell Line , Dogs , Esophagus/drug effects , Esophagus/metabolism , Ether-A-Go-Go Potassium Channels/metabolism , Gastroesophageal Reflux/drug therapy , Gastrointestinal Motility/drug effects , Humans , Male , Muscle, Smooth/drug effects , Muscle, Smooth/metabolism , Protein Binding , RatsABSTRACT
The pharmacological profile of PF-01354082, a selective 5-HT(4) receptor partial agonist, was investigated. PF-01354082 displayed high affinity for human 5-HT(4d) and dog 5-HT(4h) receptors in binding studies, having Ki values of 2.0 nM and 4.2 nM, respectively. By contrast, PF-01354082 did not show significant affinity for several other 5-HT receptors (5-HT(1A), 5-HT(1B), 5-HT(1D), 5-HT(2A), 5-HT(2B), 5-HT(2C), 5-HT(3A), and 5-HT(7)) or the dopamine D(2long) receptor. Functional assays using either cells expressing human recombinant 5-HT(4d) receptors or rat tunica muscularis mucosae demonstrated that PF-01354082 exhibited partial agonist activity at the 5-HT(4) receptor. The effects of PF-01354082 on in vitro receptor binding, ion channel activity, and sites of uptake were further investigated. PF-01354082 did not show biologically relevant binding activity at concentrations up to 10 microM except for binding to the 5-HT(4e) receptor. Furthermore, PF-01354082 decreased I(HERG) current by only 11% at a concentration of 300 microM, indicating that the compound had greater than 150,000-fold selectivity for the human 5-HT(4d) receptor over hERG channels. An in vivo study using a gastric motility model in conscious dogs demonstrated that oral administration of PF-01354082 resulted in marked and sustained stimulation of gastric motility in a dose-dependent manner. These results indicate that PF-01354082 is an orally active, highly selective, partial agonist of the human 5-HT(4) receptor that is expected to exert a favorable effect on gastrointestinal motor disorders with reduced adverse effects mediated by other related receptors.
Subject(s)
Benzimidazoles/pharmacology , Serotonin 5-HT4 Receptor Agonists , Serotonin Receptor Agonists/pharmacology , Administration, Oral , Animals , Benzimidazoles/administration & dosage , Benzimidazoles/agonists , Benzimidazoles/chemistry , CHO Cells , Carbachol/pharmacology , Cell Line , Cholinergic Agonists/pharmacology , Cricetinae , Cricetulus , Cyclic AMP/analysis , Dogs , Dose-Response Relationship, Drug , Esophagus/cytology , Gastrointestinal Motility/drug effects , Humans , Indoles/pharmacology , Kidney/cytology , Male , Muscle Contraction/drug effects , Muscle, Smooth/drug effects , Piperidines/pharmacology , Rats , Rats, Inbred Strains , Sensitivity and Specificity , Serotonin 5-HT4 Receptor Antagonists , Serotonin Receptor Agonists/administration & dosage , Serotonin Receptor Agonists/chemistry , Time FactorsABSTRACT
The P4 region of a series of oxamyl dipeptide caspase inhibitors was optimized by the combination of anti-apoptotic activity in the Jurkat/Fas (JFas) cellular assay and membrane permeability in the PAMPA assay. Two highly potent anti-apoptotic agents with moderate membrane permeability, 29 and 36, showed strong in vivo efficacy in a murine model of alpha-Fas-induced liver injury.
Subject(s)
Caspase Inhibitors , Cysteine Proteinase Inhibitors/chemical synthesis , Liver Diseases/drug therapy , Animals , Apoptosis/drug effects , Cell Membrane Permeability/drug effects , Cysteine Proteinase Inhibitors/pharmacology , Humans , Jurkat Cells , Mice , Structure-Activity Relationship , fas ReceptorABSTRACT
In the present study, binding affinities of 5-hydroxytryptamine-4 (5-HT(4)) ligands for the human 5-HT(4d) receptor were determined using the agonist [(3)H]5-HT and the selective 5-HT(4) antagonist [(3)H]GR113,808. We also compared the affinity differences between [(3)H]5-HT binding (K(H)) and [(3)H]GR113,808 binding (K(L)) with their activities as 5-HT(4) ligands. Binding studies using [(3)H]5-HT revealed that the human 5-HT(4d) receptor has two binding sites, whereas [(3)H]GR113,808 yielded a single binding site. Additionally, the number of [(3)H]5-HT binding sites decreased in the presence of guanosine-5'-O-(3-thiotriphosphate) (GTPgammaS), but the number of [(3)H]GR113,808 sites did not change. In competitive binding assays, full agonists such as 5-methoxytryptamine and tegaserod showed 2- to 8-fold higher affinities for [(3)H]5-HT binding (K(H)) than for [(3)H]GR113,808 binding (K(L)) (K(H)
Subject(s)
Indoles/pharmacology , Serotonin 5-HT4 Receptor Agonists , Serotonin Receptor Agonists/pharmacology , Sulfonamides/pharmacology , Dose-Response Relationship, Drug , Guanosine 5'-O-(3-Thiotriphosphate)/pharmacology , Humans , Serotonin/pharmacology , Serotonin 5-HT1 Receptor AgonistsABSTRACT
From hit compounds identified by high throughput screening (HTS), we have found compound 1 as a lead TRPV1 antagonist and confirmed its potential as a treatment for pain. Compound 1 has led to potent TRPV1 antagonistic benzamide derivatives ((+/-)-2: human IC(50)=23 nM, (+/-)-3: human IC(50)=14 nM in the capsaicin-induced calcium influx assay) containing indole and naphthyl moieties, obtained by elaboration of the tryptamine scaffold or via bioisosteric replacements.
Subject(s)
Analgesics/chemical synthesis , Analgesics/pharmacology , Benzamides/chemical synthesis , Benzamides/pharmacology , Combinatorial Chemistry Techniques , TRPV Cation Channels/antagonists & inhibitors , Analgesics/chemistry , Animals , Benzamides/chemistry , Humans , Mice , Molecular Structure , Rats , Structure-Activity RelationshipABSTRACT
In a mouse model of alpha-Fas-induced acute liver injury, the orally-administered caspase inhibitor PF-03491390 (formerly named IDN-6556) was retained in the liver for prolonged periods with a low systemic exposure. Reductions in the elevated plasma levels of alanine aminotransferase (ALT) revealed that the retention of PF-03491390 in the liver exerted a hepatoprotective effect, even when pre-administered to mice 4 h before alpha-Fas insult. Prolonged retention of PF-03491390 in the liver after oral administration has the benefit of low systemic exposure, making this a beneficial agent for the treatment of liver diseases.