Hemodialysis of theophylline in uremic patients

Hemodialysis of theophylline was studied in three uremic patients. The dialysis clearance ranged from 75.6 to 97.9 ml/min and averaged 88.1 ml/min. A much smaller value of 32.8 ml/min was reported by Levy and associates. The difference may be attributed to the two monitoring factors during hemodialysis, namely, blood and dialyzate flow rates. Both were higher in our study. Analysis of the semilogarithmic plots of the arterial plasma concentration versus time over a 3-hour period gave apparent half-lives of 3.15, 2.04, and 2.73 hours, respectively, for the three patients. Half-life of theophylline in normal subjects ranged from 4 to 6 hours or even longer. A prolonged half-life of theophylline in uremia could be expected. Our kinetic study indicated an approximately 50 per cent reduction in terminal half-life during hemodialysis. Hourly dialyzate was collected from one patient to account for drug recovery in the dialysis fluid. Forty per cent of the administered dose was recovered in the dialyzate during a 3-hour dialysis period, indicating effective removal. Dialysis clearance for creatinine was calculated by arterial-venous difference and correlated with that of theophylline. We found that theophylline was cleared by the dialyzer at a rate approximating 63 per cent of creatinine removal.