Discovery and synthesis of 6,7,8,9-tetrahydro-5H-pyrimido-[4,5-d]azepines as novel TRPV1 antagonists.

Utilization of a tetrahydro-pyrimdoazepine core as a bioisosteric replacement for a piperazine-urea resulted in the discovery a novel series of potent antagonists of TRPV1. The tetrahydro-pyrimdoazepines have been identified as having good in vitro and in vivo potency and acceptable physical properties.

Discovery of potent cholecystokinin-2 receptor antagonists: elucidation of key pharmacophore elements by X-ray crystallographic and NMR conformational analysis.

A novel series of cholecystokinin-2 receptor (CCK-2R) antagonists has been identified, as exemplified by anthranilic sulfonamide 1 (pK(i)=7.6). Pharmacokinetic and stability studies indicated that this series of compounds suffered from metabolic degradation, and that both the benzothiadiazole and piperidine rings were rapidly oxidized by liver enzymes. A combination of synthesis, computational methods, (1)H NMR conformational studies, and X-ray crystallographic analyses were applied to elucidate key pharmacophore elements, and to discover analogs with improved pharmacokinetic profiles, and high receptor binding affinity and selectivity.

3-[5-(3,4-Dichloro-phenyl)-1-(4-methoxy-phenyl)-1H-pyrazol-3-yl]-2-m-tolyl-propionate (JNJ-17156516), a novel, potent, and selective cholecystokinin 1 receptor antagonist: in vitro and in vivo pharmacological comparison with dexloxiglumide.

3-[5-(3,4-Dichloro-phenyl)-1-(4-methoxy-phenyl)-1H-pyrazol-3-yl]-2-m-tolyl-propionate (JNJ-17156516) is a novel, potent, and selective cholecystokinin (CCK)1-receptor antagonist. In this study, the pharmacology of JNJ-17156516 was investigated both in vitro and in vivo, and the pharmacokinetic profile was evaluated in rats. JNJ-17156516 expressed high-affinity at the cloned human (pK(I) = 7.96 +/- 0.11), rat (pK(I) = 8.02 +/- 0.11), and canine (pK(I) = 7.98 +/- 0.04) CCK1 receptors, and it was also highly selective for the CCK1 receptor compared with the CCK2 receptor across the same species ( approximately 160-, approximately 230-, and approximately 75-fold, respectively). The high affinity of JNJ-17156516 at CCK1 receptors in vitro was confirmed in radioligand binding studies on fresh human gallbladder tissue (pK(I) = 8.22 +/- 0.05). In a functional in vitro assay of guinea pig gallbladder contraction, JNJ-17156516 behaved as a competitive antagonist, with a pK(B) value of 8.00 +/- 0.07. In vivo, JNJ-17156516 produced a parallel, rightward shift in the CCK-8S-evoked contraction of the guinea pig gallbladder. The dose required to shift the CCK-8S dose-response curve was 240 nmol kg(-1) i.v. In the anesthetized rat, JNJ-17156516 produced a dose-related decrease in the number of duodenal contractions evoked by infusion of CCK-8S, with an ED(50) = 484 nmol kg(-1). Pharmacokinetic analysis of JNJ-17156516 in rats, revealed that JNJ-17156516 had a half-life of 3.0 +/- 0.5 h and a very high bioavailability (108 +/- 10%) in this species. Overall, we have demonstrated that JNJ-17156516 is a high-affinity selective human CCK1 receptor antagonist with good pharmacokinetic properties in rats.

A novel, quantitative bio-assay for cholecystokinin type-1 receptor activity in the anaesthetised rat.

INTRODUCTION: Cholecystokinin type-1 (CCK(1)) receptors mediate many of the physiological functions of CCK including delay of gastric emptying, pancreatic enzyme secretion, intestinal motility and gallbladder contractility. Existing in-vivo assays for the quantitative measurement of CCK(1) receptor mediated function are generally variable, limited in precision and require a relatively large number of animals to obtain statistically meaningful data. We found that they did not provide robust pharmacokinetic-pharmacodynamic data for profiling compounds acting at these receptors. Accordingly, here we describe a novel rat duodenal contractility assay that addresses these problems. METHODS: Rats were anaesthetised and a saline-filled balloon was inserted through the body of the stomach and secured in the duodenum approximately 1 cm from the pyloric sphincter for measurement of intra-lumenal pressure. Studies were performed to determine a dose, rate and frequency of administration of CCK8S that produced a readily quantifiable response. RESULTS: Initial experiments revealed that sustained exposure to CCK8S resulted in the rapid development of tachyphylaxis. After investigating different dosing paradigms, it was found that pulsatile delivery of CCK8S (intravenous infusion for 1 min every 10 min) produced a readily quantifiable contractile response that did not exhibit tachyphylaxis. The assay response output was defined as the number of contractions >5 mm Hg over baseline. The contractions were blocked in a dose-dependent manner by intravenous bolus injections of the CCK(1) receptor antagonists, dexloxiglumide (2 and 20 micromol/kg), and devazepide (3-100 nmol/kg) but not by the CCK(2) receptor antagonist gastrazole (10 micromol/kg). CONCLUSION: A novel, simple, high quality assay for the quantification of the in-vivo activity of CCK(1) receptor ligands is described. CCK8S delivered by pulsatile intravenous infusion to anesthetized rats produced a burst of contractile activity of the duodenum mediated by CCK(1) receptors. This activity was highly reproducible and sustained for more than 3 h providing an assay that circumvents problems associated with agonist-induced tachyphylaxis.