Chronopharmacology of the new uricosuric diuretic S-8666 in rats.

A new loop diuretic with uricosuric activity, 6,7-dichloro-5-(N,N-dimethylsulfamoyl)-2,3-dihydro-2-benzofuran carboxylic acid (S-8666), was given orally at 12:00 a.m. or 12:00 p.m. in rats. The diuretic of S-8666 and the urinary excretions of the drug and its active metabolite S-8680 (N-demethyl S-8666) were greater at 12:00 a.m. than at 12:00 p.m. Thus, the present study indicates that the diuretic effects of S-8666 varies with its administration time. Time-dependent variations in the amount of urinary excretions of S-8666 and S-8680 might be involved in the mechanisms for this phenomenon.