ABSTRACT
The synthesis and CRF receptor binding affinities of several new series of N-aryltriazolo- and -imidazopyrimidines and -pyridines are described. These cyclized systems were prepared from appropriately substituted diaminopyrimidines or -pyridines by nitrous acid, orthoester, or acyl halide treatment. Variations of amino (ether) pendants and aromatic substituents have defined the structure-activity relationships of these series and resulted in the identification of a variety of high-affinity agents (Ki's < 10 nM). On the basis of this property and lipophilicity differences, six of these compounds (4d,i,n,x, 8k, 9a) were initially chosen for rat pharmacokinetic (PK) studies. Good oral bioavailability, high plasma levels, and duration of four of these compounds (4d,i,n,x) prompted further PK studies in the dog following both iv and oral routes of administration. Results from this work indicated 4i,x had properties we believe necessary for a potential therapeutic agent, and 4i1 has been selected for further pharmacological studies that will be reported in due course.
Subject(s)
Pyridines/metabolism , Pyridines/pharmacokinetics , Pyrimidines/metabolism , Pyrimidines/pharmacokinetics , Receptors, Corticotropin-Releasing Hormone/antagonists & inhibitors , Administration, Oral , Animals , Biological Availability , Cell Line , Dogs , Humans , Mice , Pyridines/chemical synthesis , Pyridines/chemistry , Pyrimidines/chemical synthesis , Pyrimidines/chemistry , Rats , Receptors, Corticotropin-Releasing Hormone/metabolism , Recombinant Proteins/metabolism , Structure-Activity RelationshipABSTRACT
A sensitive and specific high-performance liquid chromatographic assay for the determination of corticosterone in rat plasma using dexamethasone as the internal standard is reported. Rat plasma (0.5 ml) is extracted with methylene chloride, washed with 0.1 M sodium hydroxide and then with water. The extract is analyzed by HPLC on a C18 column with ultraviolet absorbance detection at 254 nm. Pooled rat plasma was treated with activated decolorizing carbon to remove endogenous corticosterone, and was then used to prepare standards for the assay. Using 0.5 ml plasma for extraction, the detection limit of the assay is 10 ng/ml. The standard curve is linear over the concentration range 10-500 ng/ml. The recovery of corticosterone after extraction was independent of concentration and ranged from 87 to 95%. The coefficient of variation for intra-day and inter-day precision ranged from 2.4 to 7.4% and 2.1 to 8.7%, respectively. In addition, for concentrations ranging from 10 to 500 ng/ml the accuracy is within 5% of the spiked standards. The assay was utilized to examine the circadian rhythm of plasma corticosterone, and to examine the effect of immobilization stress on corticosterone levels in rats.