Pharmacokinetics of theophylline in patients following short-term intravenous infusion

Summary

Serum theophylline concentrations after intravenous administration of a new short-term infusion (Euphyllin^® Kurzzeitinfusion) were measured in 50 out-patients with chronic obstructive airways disease (COAD). An intravenous infusion of theophylline ethylenediamine 480 mg (corresponding to approximately 350 mg anhydrous theophylline) in 50 ml isotonic solution was given in 20 min. Blood samples were taken beforehand and 25 to 30 min and 1, 3 and 6 h after starting the infusion. 86% of the patients had a one-hour serum level in the therapeutic range of 8–20 mg/l, and 2 h later, this was true of 64% of the patients. The short-term infusion was well tolerated, even in cases with unknown high pre-infusion serum levels. Pertinent pharmacokinetic parameters were determined, such as total body clearance, apparent volume of distribution, and half-life of elimination. Geometric mean and 95%-confidence limits, derived from the log-normal distribution of these parameters, were: Cl=0.044 (0.018–0.109) l/h/kg ideal body weight, V_d=0.451 (0.258–0.789) l/kg ideal body weight, and t_1/2(el)=7.1 (2.6–19.1) h.