Pharmacokinetics of theophylline in ten elderly patients

The two-compartment pharmacokinetics of theophylline in ten hospitalized elderly patients with apparently normal renal, hepatic and cardiopulmonary functions was investigated after intravenous administration of the drug. Nine patients suffered from slight hemiparesis and one from Parkinson's disease. Biological theophylline half-lives of 5.4--9.0 hours and plasma clearence values of 28--42 ml kg-1hr-1 were found. The apparent volumes of distribution during the beta-phase, Vdbeta, were 0.33--0.43 1 kg-1. It is concluded that a therapeutic concentration of about 10 microgram theophylline per ml serum could be established in the investigated group of elderly patients following an intravenous initial loading dose of 3.7 mg theophylline per kg followed by a continuous infusion of 0.35 mg per kg body weight per hour. In the therapeutic use of theophylline monitoring of the serum theophylline concentration is generally advised because of the elsewhere reported variability in the biological half-life of the compound.