The influx of leukocytes (eosinophils, lymphocytes, and monocytes) into the airways and their production of proinflammatory cytokines contribute to the severity of allergic asthma. We describe here the synthesis and pharmacological evaluation of a series of triazinylphenylalkylthiazolecarboxylic acid esters that were designed to act as lung-specific antedrugs and inhibitors of the production of interleukin (IL)-5, a primary eosinophil-activating and proinflammatory cytokine. Closer examination of the hydroxypropyl ester, 15, indicated its high metabolic stability (t(1/2) > 240 min) in human lung S9 fraction but rapid conversion (t(1/2) = 15 min) into the pharmacologically inactive carboxylic acid by human liver preparations. In stimulated human whole blood cultures, 15 reduced not only the production of IL-5 (IC(50) = 78 nM) but also the biosynthesis of the monocyte chemotactic proteins MCP-1 (IC(50) = 220 nM), MCP-2 (IC(50) = 580 nM), and MCP-3 (IC(50) = 80 nM). In vivo, intratracheal administration of 15 (6 mg/animal) to allergic sheep, either before (-4 h) or after (+1.5 h) the pulmonary allergen challenge, completely abrogated the late-phase airway response and reduced the bronchial hyperreactivity to inhaled carbachol.
Stokbroekx R.A., M.G.M. Luyckx, J.J.M. Willerns, M. Janssen, J.O.M.M. Bracke, R.L.P. Joosen, and J.P. Van Wauwe: Levocabastine (R 50547): The prototype of a chemical series of compounds with specific HI-antihistaminic activity. Drug Dev. Res. 8:87-93, 1986.The synthesis and the histamine HI antagonism of four racemates of l-[cyano-4-(4-fluorophenyl)cyclohexyl]-3-methyl-4-phenyl-4-piperidinecarboxylic acid, termed R 48756, R 49389, R 49429, and R 49549, are described. R48756 (cabastine) was found to be the most potent compound, with oral ED50 values of 0.002-0.003 mglkg in both the histamineinduced lethality test (guinea pigs) and the compound 48/80 assay (rats). Upon resolution of cabastine into its two optical isomers, levocabastine (R 50547) after oral administration in guinea pigs was about four times (1 hr) to 90 times (24 hr) more potent than dextrocabastine (R 50554). Protection from dyspnea, induced by histamine aerosols, was obtained with 0.005 mglkg of levocabastine, whereas a dose of 2.5 mglkg, failed to protect guinea pigs from dyspnea induced by serotonin or acetylcholine aerosols.
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