Intersubject variability in plasma theophylline levels after oral and intravenous administration in Jordanian patients with chronic obstructive pulmonary disease.

: Plasma theophylline concentrations were determined in 151 Jordanian patients with chronic obstructive pulmonary disease. Mean plasma levels after oral administration were below the therapeutic range and significantly lower than after intravenous administration. Plasma levels in patients with congestive heart failure (CHF) were higher than in patients with no CHF. Trough plasma theophylline concentrations after intravenous administration in patients less than 18 years of age were significantly lower than in those aged 18-60 years. The overall results are in agreement with observations made in other ethnic groups.