[Pharmacokinetics and pharmacodynamics of theophylline in geriatric patients with multiple diseases].

The pharmacokinetics of theophylline (200 mg i.v.) were determined in 20 geriatric patients with multiple diseases. Serum concentrations were fitted to an open 2-compartment model. Percent changes in venous pCO2 and pO2 were used as parameters of the pharmacodynamic action. Total clearance was decreased and elimination half-life of theophylline was found to be prolonged in the elderly patients compared with data of a study with young healthy volunteers. The stronger the pharmacodynamic action of theophylline (percent change of venous pCO2 after 30 min), the faster was its elimination and the lower were measured concentrations after 2, 6, and 12 h.