Renal clearance of theophylline in man

The renal clearance of theophylline was determined in 12 experiments with six healthy human adult volunteers and was found to decrease from 8.50+/-2.20 to 276.+/-1.13 ml/min/m2 during 8 hours after oral administration of a single dose of theophylline, 200 mg/m2. There was a strong and highly statistically significant positive correlation between the renal clearance of theophylline and the urine flow rate for each subject, but there was no consistent correlation between renal clearance and plasma concentrations of theophylline.