Mathematical models of diuresis after oral administration of tizolemide, furosemide and placebo to healthy adults.

Urine volumes and flows as functions of time after oral administration of placebo, furosemide 80 mg and tizolemide 100 mg to sixteen healthy male adults at 08.00 a.m. are described through mathematical models. Accumulated urine volumes after dosing, V, as functions of time, t, are accounted for by sigmoid functions and urine flows are described as dV/dt. No significant differences were found between the 24-hour urine volume mean values after furosemide (2457 ml) and tizolemide (2283 ml) and both were significantly higher than the corresponding mean value after placebo (1369 ml) ( p less than 0.001). Peak diuresis after dosing occurs about 1.5 hours for furosemide, 4 hours for tizolemide and 6 hours for placebo. Fourteen hours after dosing, urine volume amounts to 90% of the 24-hour urine volume after furosemide and to 76% after tizolemide, so that both substances may be regarded as diurnal diuretics.