5-Acetyl-N-(1H-pyrazol-5-yl)furan-2-carboxamide as a novel orally available urea transporter inhibitor with improved...

Urea transporters (UT) serve as promising diuretic targets, as their inhibitors selectively promote urea excretion without disturbing electrolyte balance, making them suitable for long-term therapy. Based on the structural optimization of orally available diarylamide UT inhibitors Y02 and Y32 developed in our previous studies, compound 12f with enhanced diuretic efficiency and improved physiochemical properties was discovered in the present study. In vitro, 12f potently inhibited mouse UT-B and rat UT-B with IC₅₀ value of 0.11 μM and 0.054 μM, respectively, representing 14-fold and 8-fold increases in potency over Y32, and 15-fold and 12-fold increases over Y02. Oral administration of 12f (50 and 100 mg/kg) in rats induced significant, dose-dependent diuresis with a prolonged duration of up to 24∼40 h, far exceeding the effect of Y02. Pharmacokinetic studies revealed rapid absorption (t_max = 0.5 h) and improved oral bioavailability (61.9%) but short plasma half-life (t_1/2 = 0.989 h) of 12f, indicating that the prolonged efficacy was not directly attributed to sustained systemic exposure of the parent drug but other mechanisms which required for further investigation. Molecular docking study indicated that 12f formed multidimensional interactions with the active binding site of both UT-B and UT-A2 proteins, implying a predictable inhibitory effect to UT-A families which is beneficial for diuretic activity. Additionally, 12f exhibited 5-fold and 18-fold higher aqueous solubility than Y32 and Y02, respectively, suggesting a superior in vivo transport characteristic. Collectively, 12f is a promising orally available salt-sparing diuretic candidate targeting urea transporters, with great potential for the treatment of diseases requiring long-term diuretic therapy.