Discovery of FR166124, a novel water-soluble pyrazolo[1,5-a]pyridine adenosine A1 receptor antagonist

Article abstract of DOI:10.1016/S0960-894X(99)00304-2

Novel 3-(2-cycloalkyl and cycloalkenyl-3-oxo-2,3-dihydropyridazin-6- yl)-2-phenylpyrazolo[1,5-a]pyridines were synthesized and evaluated for their adenosine A₁ receptor binding activities. In this series, FR166124 (3) was found to be the most potent and selective adenosine A₁ receptor antagonist, and the double bond of the cyclohexenyl acetic acid group was essential for selectivity of A₁ receptor binding. Furthermore, the solubility in water of the sodium salt of FR166124 was high.